hypothesis about pollution

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Unbundling the Pollution Haven Hypothesis

• M. Scott Taylor

The "Pollution Haven Hypothesis" (PHH) is one of the most hotly debated predictions in all of international economics. This paper explains the theory behind the PHH by dividing the hypothesis into a series of logical steps linking assumptions on exogenous country characteristics to predictions on trade flows and pollution levels. I then discuss recent theoretical and empirical contributions investigating the PHH to show how each contribution either questions the logical inevitability, or the empirical significance of one or more steps in the pollution haven chain of logic. Suggestions for future research are also provided.

©2011 Walter de Gruyter GmbH & Co. KG, Berlin/Boston

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The scientific method and climate change: How scientists know

By Holly Shaftel, NASA's Jet Propulsion Laboratory

The scientific method is the gold standard for exploring our natural world. You might have learned about it in grade school, but here’s a quick reminder: It’s the process that scientists use to understand everything from animal behavior to the forces that shape our planet—including climate change.

“The way science works is that I go out and study something, and maybe I collect data or write equations, or I run a big computer program,” said Josh Willis, principal investigator of NASA’s Oceans Melting Greenland (OMG) mission and oceanographer at NASA’s Jet Propulsion Laboratory. “And I use it to learn something about how the world works.”

Using the scientific method, scientists have shown that humans are extremely likely the dominant cause of today’s climate change. The story goes back to the late 1800s, but in 1958, for example, Charles Keeling of the Mauna Loa Observatory in Waimea, Hawaii, started taking meticulous measurements of carbon dioxide (CO 2 ) in the atmosphere, showing the first significant evidence of rapidly rising CO 2 levels and producing the Keeling Curve climate scientists know today.

“The way science works is that I go out and study something, and maybe I collect data or write equations, or I run a big computer program, and I use it to learn something about how the world works.”- Josh Willis, NASA oceanographer and Oceans Melting Greenland principal investigator

Since then, thousands of peer-reviewed scientific papers have come to the same conclusion about climate change, telling us that human activities emit greenhouse gases into the atmosphere, raising Earth’s average temperature and bringing a range of consequences to our ecosystems.

“The weight of all of this information taken together points to the single consistent fact that humans and our activity are warming the planet,” Willis said.

The scientific method’s steps

The exact steps of the scientific method can vary by discipline, but since we have only one Earth (and no “test” Earth), climate scientists follow a few general guidelines to better understand carbon dioxide levels, sea level rise, global temperature and more.

• Form a hypothesis (a statement that an experiment can test)
• Make observations (conduct experiments and gather data)
• Analyze and interpret the data
• Draw conclusions
• Publish results that can be validated with further experiments (rinse and repeat)

As you can see, the scientific method is iterative (repetitive), meaning that climate scientists are constantly making new discoveries about the world based on the building blocks of scientific knowledge.

“The weight of all of this information taken together points to the single consistent fact that humans and our activity are warming the planet." - Josh Willis, NASA oceanographer and Oceans Melting Greenland principal investigator

The scientific method at work.

How does the scientific method work in the real world of climate science? Let’s take NASA’s Oceans Melting Greenland (OMG) campaign, a multi-year survey of Greenland’s ice melt that’s paving the way for improved sea level rise estimates, as an example.

• Form a hypothesis OMG hypothesizes that the oceans are playing a major role in Greenland ice loss.
• Make observations Over a five-year period, OMG will survey Greenland by air and ship to collect ocean temperature and salinity (saltiness) data and take ice thinning measurements to help climate scientists better understand how the ice and warming ocean interact with each other. OMG will also collect data on the sea floor’s shape and depth, which determines how much warm water can reach any given glacier.
• Analyze and interpret data As the OMG crew and scientists collect data around 27,000 miles (over 43,000 kilometers) of Greenland coastline over that five-year period, each year scientists will analyze the data to see how much the oceans warmed or cooled and how the ice changed in response.
• Draw conclusions In one OMG study , scientists discovered that many Greenland glaciers extend deeper (some around 1,000 feet, or about 300 meters) beneath the ocean’s surface than once thought, making them quite vulnerable to the warming ocean. They also discovered that Greenland’s west coast is generally more vulnerable than its east coast.
• Publish results Scientists like Willis write up the results, send in the paper for peer review (a process in which other experts in the field anonymously critique the submission), and then those peers determine whether the information is correct and valuable enough to be published in an academic journal, such as Nature or Earth and Planetary Science Letters . Then it becomes another contribution to the well-substantiated body of climate change knowledge, which evolves and grows stronger as scientists gather and confirm more evidence. Other scientists can take that information further by conducting their own studies to better understand sea level rise.

All in all, the scientific method is “a way of going from observations to answers,” NASA terrestrial ecosystem scientist Erika Podest, based at JPL, said. It adds clarity to our way of thinking and shows that scientific knowledge is always evolving.

Related Terms

• Climate Change
• Climate Science
• Earth Science

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• v.6(30); 2021 Aug 3

Plastic Pollution: A Perspective on Matters Arising: Challenges and Opportunities

Austine ofondu chinomso iroegbu.

† Department of Chemical Sciences, University of Johannesburg, Doornfontein 2028, Johannesburg, South Africa

‡ Centre for Nanostructures and Advanced Materials, DSI-CSIR Nanotechnology Innovation Centre, Council for Scientific & Industrial Research, CSIR, Pretoria 0001, South Africa

Suprakas Sinha Ray

Vuyelwa mbarane.

§ State Information Technology Agency (SITA), 459 Tsitsa Street, Erasmuskloof 0048, Pretoria, South Africa

João Carlos Bordado

∥ Centro de Recursos Naturais e Ambiente (CERENA), Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal

José Paulo Sardinha

Plastic pollution is a persistent challenge worldwide with the first reports evidencing its impact on the living and nonliving components of the environment dating back more than half a century. The rising concerns regarding the immediate and long-term consequences of plastic matter entrainment into foods and water cannot be overemphasized in light of our pursuit of sustainability (in terms of food, water, environment, and our health). Hence, some schools of thought recommend the revisitation and continuous assessment of the plastic economy, while some call for the outright ban of plastic materials, demonstrating that plastic pollution requires, more than ever, renewed, innovative, and effective approaches for a holistic solution. In this paper, dozens of reports on various aspects of plastic pollution assessment are collated and reviewed, and the impact of plastic pollution on both the living and nonliving components of the environment is discussed. Current challenges and factors hindering efforts to mitigate plastic pollution are identified to inform the presented recommendations while underscoring, for policymakers, stakeholders, and the scientific community, the exigency of finding sustainable solutions to plastic pollution that not only encompass existing challenges but also future threats presented by plastic pollution.

1. Pollution—An Overview

Pollution is a global phenomenon, a persistent challenge that is transnational (i.e., borderless) in nature, transinstitutional in purview, and transdisciplinary in solution scope. 1 − 3 As indicated in Figure ​ Figure1 1 , pollution can arise naturally, for example, by saltwater intrusion into freshwater resources and volcanic eruptions that release dangerous gases, or it can be manmade, a result of anthropogenic activities such as the exploitation of the environment and its resources and the introduction of matter or energy into the environment that are not natural to it. 4 − 6 Substances or energies (e.g., material entropy) that are introduced into the environment through anthropogenic activities can upset and compromise the natural balance of the earth’s intricate and inter-related systems, causing a “domino effect”. 7 − 9 Pollution can also be considered as (an) unnatural disturbance(s) arising from the intrusion of energy or matter into the environment, which may result in the interruption (i.e., modification) or degradation of the natural state of a system or environment, thereby increasing the risk of the system or environment deviating from its initial state (i.e., original conditions and functions). For example, the water present in commercial petroleum products (e.g., gasoline) can be considered a pollutant because it affects the original conditions and functions of these products in motor engines. Hence, it can be inferred that chemical reactions usually occur as a result of unnatural disturbances (i.e., the agitation or excitation of the state of matter or a system), causing the transformation or transmutation of substances (i.e., matter) from one form to another (which may be reversible or irreversible); accordingly, pollution has the potential to change the dynamics of matter and environments, which consequentially impacts the natural characteristics of living and nonliving components. 8 , 10 Notwithstanding, we hold that matter or energy entering an environment cannot be considered pollution (or a pollutant) if the effect of such intrusion or disturbance on the environment or system is not negative, i.e., is (i) neutral or (ii) positive. Hence, we posit that meeting these conditions should be the basis for considering such matter or energy as “green” or “eco-friendly”. For example, sunlight is considered friendly to green vegetation but unfriendly to plastic materials; in the former, it is vital for photosynthesis, and in the latter, it is known to promote photodegradation.

Common sources of pollution.

Pollution has detrimental consequences, which cannot be overstated in light of current environmental challenges. For example, it has been reported that a slight deterioration in air quality, owing to pollution, significantly impairs the natural behavior of bees, interrupting their critical roles in the ecosystem and thereby threatening food security. 11 Elsewhere, it has been found that a strong correlation exists between congenital anomalies and community exposure to chemicals associated with environmental contaminants. 12 A recent study has shown that the deterioration in the quality of milk in breastfeeding mothers can be traced to environmental pollution; it further contends that pollutants, such as polychlorinated biphenyls (PCBs), entering the human body have the potential to disrupt and alter the natural balance of a mother’s milk with health consequences for breastfeeding infants that can range from allergies and endocrine disorders to impaired neurodevelopment. 13 To place the existential threat of pollution in context, a global health assessment has established that more than 20% of global deaths can be traced to pollution-related health complications. 14 Pollution impacts almost every aspect of our existence and the living and nonliving components of the environment. For example, satellite data spanning three decades evidence the devastating impact of global warming (a result of environmental pollution), which has shrunk Greenland’s ice sheets to almost nothing, thus contributing to rising global sea levels. 15

Plastic pollution is a pressing global challenge owing to the pervasive, near-unmanageable threat it poses to living and nonliving systems and the environmental stress it causes. 16 , 17 Herein, we define plastic pollution (encompassing macro-, micro-, and nanoplastic debris) as the intrusion or invasion by plastic materials (i.e., polymeric systems), either through direct introduction or degradation processes, of environments (to which they are not native) to negatively or undesirably impact such environments. Similar to greenhouse gases, persistent pollutants, and other environmental contaminants, plastic pollution cannot be restricted by territorial boundaries or legislation because it is able to migrate between water bodies, disperse through air, and be transported to remote locations through human intervention. 18 − 20

The following criteria are considered conditions for qualifying a pollutant as hazardous to the environment: 8 (i) its biological impact even at minute concentrations is significant (noticeable and observable); (ii) it easily diffuses into the atmosphere, is soluble in water, and has an affinity for accumulating in environments; (iii) it tends to persist in a given environment; (iv) it can impact a wide range of targets (living and nonliving), especially those directly linked to human health or important for environmental stability and functions; (v) its degradation byproducts or their combination with other environmental chemical compounds exhibit toxicity, persist, and accumulate in a target or exceed the original levels of the material; (vi) it is suitable for large-scale production and its benefits are considered to outweigh the concomitant cost of pollution. This perspective shows that plastic pollution satisfies all of these criteria and, thus, is hazardous to both living and nonliving systems in the environment.

A Google Scholar search using the search criteria “Plastic Pollution” at 10-year intervals in the last seven decades reveals that the number of publications on plastic pollution has increased, as shown in Figure ​ Figure2 2 . Across the world, the issue of plastic pollution has brought about a paradigm shift in discourses on climate change and ocean and environmental sustainability. 21 , 22 In almost every country in the world, multiple individuals and groups have become environmental activists against plastic pollution. 23 In addition, governments, world leaders, and various stakeholders participate in discussions, conventions, and resolutions in concerted efforts to find a holistic solution to plastic pollution. 24 , 25

Number of publications between 1952 and 2021 on plastic pollution. The search engine was Google Scholar, while the keyword for the search was Plastic Pollution.

However, despite being a half-century-old problem, it is evident that the threat posed by plastic pollution is not abating and remediation will require, more than ever, renewed effort and a holistic approach with concrete commitments from all stakeholders. Borrelle et al. 17 estimated that more than 10% of the global plastic waste generated in 2016 found its way into aquatic environments. Moreover, they forecast that, without immediate intervention, by 2030, the world’s aquatic environments could contain more than 80 metric ton (Mt) of plastic debris. 17 Such a volume of plastic added to the world’s aquatic environments would displace an equal volume of water, shrinking aquatic habitats, increasing the likelihood of floods, and exacerbating global warming; 2 these phenomena, in turn, have countless negative consequences, such as endangering individuals and communities, destroying properties, and straining healthcare facilities and resources, government budgets, and the insurance industry, demonstrating the wider impact of plastic pollution. 26 − 28

Concerns regarding the mounting challenges of pervasive environmental and biological stressors, chiefly arising from the short- and long-term impacts of plastic pollution, have prompted the consolidation of the efforts (and associated financial, scientific, economic, and political resources) of stakeholders, worldwide, in the form of a sustainable development goal (SDG) initiative that prioritizes sustainable and healthy earth for all. 29 Therefore, discourses on environmental pollution such as plastic pollution should evaluate challenges, possible amelioration/mitigation, or control, with reference to the SDGs and current environmental issues.

This perspective differs from existing publications on plastic pollution ( Table 1 ) as it underscores key challenges and factors hindering global efforts to mitigate the menace of plastic pollution while highlighting various views on plastic pollution. It also discusses important developments and initiatives, aimed at mitigating the environmental impacts of plastic pollution, and presents recommendations that are based on a multidisciplinary approach. Policymakers, stakeholders (i.e., the plastic economy value chain), and the scientific community are alerted to the exigency of synergistically reshaping the current plastic economy to demonstrate a commitment toward the pursuit of green(er) plastics and support of blue sea initiatives, focusing on sustainable solutions that address the existing and future challenges presented by plastic pollution.

Plastics are polymeric systems (i.e., macromolecules), for example, polyethylene, polyacrylamides, polyesters, and polypropylene. Although plastics are generally polymers, not all polymers are plastics, such as natural cellulose, carbohydrates, proteins (e.g., leather), lignin, and natural rubber ( Hevea brasiliensis ). In this perspective, we consider plastic pollutants to be polymer-based materials in the environment, which may be plastics or not, that are potentially harmful.

2. A World of Polymers

We have always lived in the polymer age. Humans are essentially polymeric, from the deoxyribonucleic acid (DNA) that encodes our human traits to the protein that covers our body (skin) and our keratin-laden hair. Moreover, our living, walking polymeric forms are sustained by the polymers we consume in the forms of carbohydrates and proteins and protected by the polymer-based clothes we wear. Advances in polymer science and engineering over the years have led to the discovery and commercialization of various polymer-based systems or materials such as polycarbonates, nylons, polyimides, polyurethanes, and liquid crystals, which have found various domestic and industrial applications that shape our world and advance our quality of life. Polymers feature prominently in almost every sector of the economy, from industries that manufacture pharmaceuticals, composites, and tires to laboratories that perform DNA profiling for criminal investigations by law enforcement agencies, demonstrating that polymers and polymer science have contributed and continue to contribute to civilization; additional examples are presented in Figure ​ Figure3 3 . 35 − 38 Owing to great minds such as Hermann Staudinger (1881–1965), Wallace Hume Carothers (1896–1937), Paul J. Flory (1910–1985), and Stephanie L. Kwolek (1923–2014) advancing the field of polymer science and engineering, plastics are considered one of man’s greatest feats in the field of science and technology. 39 , 40 In 1962, Fred Wallace Billmeyer Jr. (1919–2004) predicted that, with advances in polymer science and engineering, plastics will become the dominant materials of the future, surpassing steel, aluminum, and copper. 41 More than half a century later, this prediction seems accurate as, in recent times, plastics have outperformed competing materials, including wood, metal, and glass, as the material of choice in diverse domestic and industrial applications; the production of plastics exceeded 8 billion Mt between 1950 and 2015. 2 , 42

Immense contributions of polymers to human advancement and civilization cannot be overstated; polymers feature heavily in almost every sector of the economy.

Owing to their flexibility and adaptability for various applications, lightweight, moisture resistance, corrosion resistance, and low-cost plastics are sought-after materials for various applications. Commodity plastics such as polypropylene, which is a very cost-effective polymeric material that can be blow-molded, extruded, thermoformed, or injection-molded, are popular for the fabrication of products such as packaging films, plastic crates used for good transportation, storage containers (e.g., ice cream containers and yogurt containers), plastic caps, jerry cans, and hair combs. Other well-known commodity plastics include poly(vinyl chloride) (generally known as PVC and employed in piping and insulation systems), polyethylene (generally employed in packaging films), and poly(ethylene terephthalate) (PET; generally employed in beverage packaging). 36 , 43 Since our reliance on polymers increases in step with advances in science and technology (e.g., robotics, artificial intelligence, synthetic organs, insulation for energy conservation, and smart materials), a future that is not enriched and heavily dependent on plastics seems unlikely. 43 − 45

3. Health and Environmental Issues

There is no gainsaying that plastics have contributed immensely to the rise of human civilization; however, the distribution of plastic debris (macro-, micro-, and nanoplastics) in the environment and its entrainment into biological systems have become a serious issue. 46 Various health conditions such as thyroid dysfunction, obesity, diabetes, and reproductive impairment have been attributed to plastic pollution. 47 For example, it has been shown that nanoplastics impact negatively the composition and diversity of microbial communities in the human gut, which, considering emerging research evidencing the strong relationship between the gut and neural networks in the brain, could negatively impact the endocrine, immune, and nervous systems. 20 As already highlighted, pollution changes the dynamics of systems and environments with consequential impacts on the natural characteristics of their living and nonliving components; thus, it is reasonable to infer that the entrainment of nanoplastics into the human gut holds physiological consequences. The genotoxicity of micro- and nanoplastics to DNA has been established. It has been demonstrated that if the plastic matter is small enough to cross the nuclear membrane surrounding the DNA, damage can occur, impairing the DNA structure or forming lesions, which, unrepaired or misrepaired, can cause mutagenic processes that are considered to play a role in the carcinogenesis of cells. Additionally, it was found that the type and level of damage of DNA depend on the shape, functional groups, and chemical composition of the plastic debris. 48 The human airway is a key pathway for plastic fiber entrainment into the lungs, and biopersistence of the fibers depends on their length, structure, and chemical composition. Moreover, at certain exposure limits, all plastic fibers are likely to produce inflammation, which can lead to lung challenges such as the formation of reactive oxygen species with the potential to initiate cancerous growth through secondary genotoxicity. 49 Although there are few studies on the extent of the damage that prolonged exposure to plastic particles can cause to the human body (suggesting the need to increase research in this area), it is accepted that industry workers at textile facilities are at a high risk of contracting occupational diseases arising from high exposure to textile fibers. 50 It has long been established that constituents of plastic packaging chemically interact with or migrate into fat-containing foods; typical interactions include the migration of antioxidants from the plastic packaging into the food, sometimes bonding to the food surface. 51 Such transfer of packaging additives from the packaging material to its food content is a potential health risk. Furthermore, PET, a common plastic employed in the food and beverage industry, is a source of endocrine disruptors; 52 these endocrine disruptors leach from the plastic packaging into the consumables that it contains. Even at standard room temperature, phthalates (potential endocrine disruptors) are known to leach from PET packaging into various food contents in the presence of water. 52

The low thermal conductivities of plastic materials, although considered advantageous in certain applications (e.g., heat insulation), 43 contribute to global warming when these plastics are distributed in aquatic environments; they displace equal volumes of water and restrict heat flow from the sun to the aquatic environment, leading to a rise in sea levels and the dissipation of energy into the immediate environment. 2 The degradation pathways of plastics in the environment can also contribute to environmental stress. For example, Gewert et al. 53 posited that PVC, a very unstable polymer in the presence of UV radiation (+ h v), undergoes dechlorination in the environment, forming polyene moieties and hydrochloric acid (HCl) in the presence of water, as shown in Scheme 1 .

Reproduced with permission from Gewert, B.; Plassmann, M. M.; MacLeod, M. Pathways for degradation of plastic polymers floating in the marine environment. Environ. Sci.: Process. Impacts 2015 , 17, 1513–1521. 53 Copyright 2015, Royal Society of Chemistry, UK.

This dechlorination process and subsequent release of HCl have the potential to contribute to the acidification of aquatic environments by decreasing the pH level, in addition to the acidification caused by atmospheric CO 2 . It has been highlighted that increasing ocean acidity will aggravate global warming, 54 , 55 detrimentally affecting and possibly mutating habitats and the characteristics of various environments 56 , 57 to seriously undermine our goal of sustainable earth for future generations. However, a major concern must be raised at this point: the risk posed by PVC debris on living systems. Can PVC debris find its way into living systems? If it can, does it follow the above-mentioned degradation pathway? If it does, what health challenges do direct dechlorination and the subsequent release of HCl present living systems such as humans?

The load-bearing capacity of an environment is considered finite and it is believed that exceeding this capacity of an environment (and its living and nonliving components) to tolerate stressors such as synthetic waste (e.g., plastic debris) can result in unpredictable, possibly catastrophic, situations owing to a butterfly effect. 9

4. Challenges Associated with Plastic Pollution Mitigation

Factors militating against efforts to manage and limit the negative environmental impacts of plastic pollution are numerous and multifaceted; they include economic and political factors, a lack of commitment by governments and global plastic economy stakeholders, dissenting opinions of scientists, and under-reported or overlooked polluters. 2 , 58 − 61 Here, we highlight a few important challenges. For example, in October 2020, it was reported that the United States generated an estimated 42 Mt of plastic waste in 2016, of which between 0.14 and 0.41 Mt was allegedly dumped illegally into the environment (land and water) and another 0.15–0.99 Mt was exported to other countries such as South Africa, Indonesia, and Mexico, where it was inadequately recycled (either burnt or discarded in open landfill sites). It was further stated that between 2010 and 2016, the United States was the most significant contributor to plastic pollution in the environment, overtaking China. 62 This indicting report of a technologically and economically advanced country such as the United States and others 63 demonstrates one of the key challenges facing global efforts to mitigate plastic pollution, i.e., the tendency of global powers to pass the responsibility for their generated waste on to poorer nations, who are less equipped to recycle or manage the waste. Hence, we contend that the issue of plastic pollution and its mitigation strategies transcend the generally narrow public focus on single-use carrier bags (although they contribute to the problem) and concern powerful stakeholders such as multinational corporations and top brands that have the capacity (financially, politically, etc.) to undermine or circumvent concerted global efforts to address plastic pollution. For example, based on an audit undertaken in more than a dozen countries, it was found that well-known global brands, such as Coca-Cola, Nestlé, PepsiCo, and Unilever, are among the top sources of plastic pollution (for the third consecutive year); 64 yet, there are scant reports of these brands taking ownership of the environmental threat posed by plastic packaging used in their products, especially in countries in sub-Saharan Africa (e.g., Nigeria). 65

Multiple studies have demonstrated that automobile tires are significant contributors to microplastic pollution in the environment. For example, Kole et al. 66 demonstrated that the wear and tear of tires contribute significantly to the entrainment and distribution of plastic particles in the environment. They estimate the annual per capita emission of tire particles to range between 0.23 and 4.7 kg, with a global average of 0.81 kg. Furthermore, they contend that 5–10% of the plastic pollution in aquatic environments is derived from automobile tires, while 3–7% of the plastic particles in the air that we breathe is derived from automobile tires, which is a significant contribution to the global air burden. 66 However, they did not collate data on the amount of plastic matter, derived from tires, that enters the food chain (through water and air), or how much is consumed by ruminants owing to plastic matter trapped/settled on their food sources, e.g., grasses. Furthermore, they did not include comprehensive data from the wear and tear of bicycle tires or tires employed in the aviation industry since reports that quantify the contributions of these categories of plastic polluters are limited. A related study quantified the relative abundance of plastic matter (i.e., microplastic debris) generated by the wear and tear of automobile tires at roadside drains and in the natural environment near major road intersections, finding that it ranged from 0.6 ± 0.33 to 65 ± 7.36 in 5 mL of sampled material. The report also noted that plastic debris tends to act as a vector for other hazardous systems and thus persists in the environment with serious negative consequences. 67 Owing to increasing concerns that automobile users contribute substantially to microplastic distribution in the environment, the Swedish Government commissioned the Swedish National Road and Transport Research Institute (VTI) to conduct a comprehensive study of this matter between 2018 and 2020. The key findings of their study are summarized. 68

• At least half of Sweden’s microplastic pollution derives from tires.
• Particles as large as 20 μm are deposited on or near roads and are carried off by winds to remote places. In addition, rain or snow clean-up processes transport these particles to other locations.
• Stormwater transports tire-based microplastics into open waters, reservoirs, and containment areas.
• It is necessary to further investigate the transportation and fate of these generated microplastics in sewerage and natural organisms.

Notwithstanding the mounting evidence of tire-based microplastic pollution, the multibillion-dollar tire industry is resisting scrutiny of its contribution to plastic pollution and the imposition of sanctions and regulations through the intense lobbying of European Union (EU) lawmakers. The report further highlighted how the tire industry commissioned and published no less than ten studies to counter reports revealing the significant risk that tire particles pose to humans and the environment; 69 again demonstrating how polluters undermine efforts to mitigate the plastic pollution caused by their products. In addition, several studies have argued that because tire particles contain toxic substances, such as polycyclic aromatic hydrocarbons (phenanthrene, butylated hydroxyanisole, 2-methylnaphthalene, etc.) that are considered to pose serious health risks to living systems, 70 , 71 their distribution in the environment should not be trivialized.

Another factor limiting efforts to mitigate plastic pollution is the dissenting opinions and counteropinions held by scientists on various aspects of plastic pollution, e.g., sources, risk assessment, and toxicology. For example, Stafford and Jones 72 opine that addressing plastic pollution, such as ocean plastic pollution, is less pressing than addressing other environmental challenges such as climate change and biodiversity loss. They insist that emerging reports highlight the exigency of directing global efforts toward mitigating carbon emissions rather than expending energy on lesser threats, such as marine plastics. They further suggest that although ocean plastic pollution is a problem that needs attention, it does not pose an immediate ecological or toxicological threat at a planetary boundary level (i.e., the threat posed by plastic pollution is contextually less pressing than the threats posed by climate change and biodiversity loss that have long exceeded core planetary boundaries). 72 However, Avery-Gomm et al. 73 have challenged the position of Stafford and Jones, 72 arguing that global threats must continually be kept in perspective because undermining one threat by substituting it with another so-called “heftier” threat would be counterproductive in the global pursuit of sustainability. In their concluding remarks, they posit that the continuous discourse on plastic pollution has informed the improvement of the monitoring and risk evaluation of plastic pollution, as well as the development of frameworks for mitigation and remediation. 73 Elsewhere, an environmental toxicologist and risk assessor has argued that microplastics in marine and freshwater ecosystems do not pose any threat to the aquatic habitat as long as these pollutants are in low concentrations, despite the contradictory views of fellow scientists, referring to the threat posed by microplastics to aquatic habitats as a superficial risk. 74 However, this trivialization of the threat posed by plastic pollution on not only aquatic habitats but also terrestrial and arboreal environments is strongly rejected by Hale, 75 who insists that there is no basis to downplay the threat posed by plastic pollution to aquatic habitats. Hale contends that, in addition to plastic particle size, assessments of the toxicological impacts and consequences of plastic pollution in any given environment must consider the chemical compositions of the polymeric materials employed in the manufacture and production of the plastic materials; the shapes, surface areas, density, and persistence of the plastic particles; as well as the effects of additives (e.g., modifiers) and even sorbed pollutants (e.g., carriers and/or transfer agents). 75 Hale’s position is supported by Kramm et al., 76 who add that plastic pollution is a prototypically global and complex anthropogenic issue. They hold that a reductionist approach to addressing a serious environmental issue such as that presented by plastic pollution is detrimental to mitigation efforts. Moreover, they consider it high time that the scientific community takes responsibility for the environmental problems resulting from the work and inventions of scientists rather than trivializing or shirking responsibility. 76 Although some scientists may want to trivialize the threat of plastic pollution, it is generally accepted that any substance or energy can become toxic and environmentally disruptive at sufficient concentrations. 8 The fundamentally different opinions of scientists are a key challenge to forging cooperation; after all, a house divided against itself cannot stand. Such differences also convey disunity and present avenues or opportunities for plastic polluters to exploit, to avoid responsibility, to the detriment of the environment and, by extension, humanity.

Studies have evidenced that textiles and fibers are major contributors to the plastic materials that entrain into human lungs, food, and the environment ( Table 2 ). 49 , 77 However, because clothing is a primary human need, the textile industry directly and indirectly employs more than 100 million people globally and is a significant contributor to the gross domestic product (GDP) and economic growth of various nations. 78 , 79 In this context, addressing the plastic pollution resulting from the use of textiles and fibers is a challenge since any approach will have consequences (whether that approach involves banning the use of textiles and fibers or mitigating their contribution to plastic pollution as much as possible). Figure ​ Figure4 4 shows how much textile lint accumulates in the lint trap of a commercial dryer in a laundry house. This commercial dryer features a trap that prevents lint from escaping; however, washing machines and dryers that do not feature appropriate filtration systems release significant volumes of textile fibers into the environment.

Lint accumulation from a winter blanket in a commercial dryer. (A) Winter blanket loaded inside a commercial dryer. (B) Accumulation of lint inside the lint trap during the drying of the blanket. (C) Unweighed lint accumulated in the lint trap from the winter blanket after a single dry cycle. Photo Credit: First author (AOCI).

Moreover, considering that most polymers employed in the manufacturing of synthetic fibers and textiles are derived from petroleum and fossil-based resources, plastic pollution mitigation becomes a challenge (especially for oil-dependent economies) when balancing economics and politics. 80 , 81

Products and polymer-based articles, such as toothbrushes, shoes (materials or soles may be made from plastics), insulated electrical cables and equipment, light switches, writing pens (i.e., plastic cases), writing and printing inks (employ polymeric systems such as drag-reducing agents and stabilizers), mattresses, wigs and artificial hair (usually derived from high-performance polymers), artificial nails (e.g., acrylics), kitchen wipes (composed of microfibers), automobile paints, phone casings, computer casings, plastic wristwatches, and marine paints, are usually overlooked or underestimated as significant contributors to plastic pollution. Collectively, the “insignificant” contributions of these products or articles to plastic pollution, owing to poor disposal or through the process of wear and tear/degradation, is less insignificant. Notwithstanding, several reports focus on single-use plastic carrier bags as the primary plastic pollutant menacing our environment. 84 , 85 While we do not fault the positions held by these scientists, we argue that almost everyone releases plastic matter into the environment on a daily basis, e.g., through the shedding of textile fibers from our clothing. Hence, a more holistic approach to the management and control of plastic pollution is necessary to realize a sustainable environment. A small leak will sink a great ship; hence, we must beware of the plastic fibers that billions shed from their clothes daily or that is derived from insignificant contributors. It is our opinion that most people have little or no idea that their footwear (made from polymeric materials) also contributes to plastic pollution in the environment through wear and tear. As people tread on road surfaces, these surfaces abrade their footwear and accumulate plastic particles, which are subsequently washed away by rain into open waters. Furthermore, reports on the contributions of automobile and marine paints/coatings to plastic pollution through wear and degradation are limited. We submit that the contributions of automobile and marine paints/coatings to plastic pollution must be analyzed and quantified, as they represent potential secondary or primary sources of micro- and nanoplastic stressors in the environment. Moreover, the advanced paints and coatings (e.g., anticorrosive paints and coating) 86 , 87 that scientists and technologists are developing may pose additional environmental challenges when such materials leach, degrade, or form sediments in particular environments. It is worth noting that during the environmental degradation of paints and coatings, sorbed pollutants or additives may combine with biogenic systems and unpredictably alter living and nonliving systems in the environment. These plastic pollutant sources are usually overlooked or understudied, resulting in a knowledge gap that must be addressed to formulate a holistic approach to the management and control of plastic pollution in various environments.

5. Opportunities

Evidently, plastic pollution is a global challenge, and, as has been demonstrated, it meets all of the criteria of an environmental hazard for both the living and nonliving components of the environment. It is also apparent that a plastic-free future is unlikely despite the threat plastic pollution poses to the environment. 25 In addition, emerging data indicate an increase in global plastic pollution owing to the demand for personal protective equipment, 88 , 89 such as facemasks, to limit the spread of COVID-19. Besides, even if we were to ban the production and use of plastics, we would still need to address the plastic pollution currently present in our water, atmosphere, soil, consumables (e.g., table salts), and even vegetation (e.g., wheat and lettuce). 90 − 92 Hence, concerted global efforts are required to mitigate, manage, and control the current and possible future threats plastic debris distribution in the environment poses to its living and nonliving systems. Fortunately, various courses of action can be taken to realize this goal.

5.1. Plastic Education in National Curricula

Because prevention is better than cure, environmental responsibility and sustainability must be taught (formally and informally) from childhood, be it at home or in religious or formal education settings, to instill an appreciation of life and the environment. Such an educational approach is comparable to comprehensive sex education (CSE) that forms part of school curricula and teaches students life skills that enable them to make appropriate and healthy choices concerning their sexual lives. 93 We hold that incorporating plastic education into the national curricula is critical to mitigating, managing, and controlling plastic pollution and fostering sustainability. 94 We have enumerated elsewhere 2 the opportunities a plastic education curriculum presents. Hence, we support the call by the comity of nations for a global curriculum on plastic pollution, taught from kindergarten to the tertiary level, that addresses existing and emerging environmental and sustainability goals and objectives. For example, it has been established that handwashing clothes limits the amount of plastic fibers that ends up in the environment and prolongs the life span of fabrics. Although most people would consider using washing machines to do their laundry, a greater understanding of the limitations of these conveniences in mitigating plastic pollution may change behavior. It is believed that one of the reasons plastic pollution persists is the disconnect between scientific knowledge and the formative knowledge of the population. The population should be equipped with sufficient knowledge concerning the dangers and detrimental impact of plastic pollution (i.e., heightened risk awareness); instilling this risk awareness through formative education from childhood will promote the acceptance and support of policies and initiatives formulated to mitigate plastic pollution.

Religious and cultural institutions must actively participate in educating society on the value of sustainable earth and environment. It has been observed that culture, tradition, and religion all overwhelmingly influence the psyche, politics, emotional intelligence, and approach to life of individuals; 95 , 96 hence, addressing a global issue such as plastic pollution requires a rethink of our educational systems and the roles they play in promoting a sustainable environment. Human behaviors are ranked as some of the main challenges to addressing environmental issues; however, educational, religious, cultural, and traditional organizations can influence the attitudes and behaviors of their members in terms of environmental issues and are best placed to convince the population of the dire need to manage and control plastic pollution through behavioral change and ethical best practice. 2 , 97

Furthermore, global education systems should place greater emphasis on “responsible science”, where every scientific pursuit considers the environment to avoid engineering our own destruction. Scientists must understand that sustainability is their core mandate and must take ownership of the environmental challenges in which they are complicit. We believe that the formal and informal education sectors are critical to achieving the SDGs 29 and posit that plastic pollution mitigation, management, and control can only be achieved through the cooperation of all stakeholders, i.e., every human on the earth, for divided we fall. In closing, we emphasize that incorporating plastic education in national curricula to increase risk awareness is an opportunity that should not be squandered.

5.2. Green(er) Alternatives

We have previously mentioned that for a material to be considered green or eco-friendly, the effect of its intrusion or degradation in any given environment should either be neutral (have no net effect) or positive (energy-efficient, easily recyclable or reusable, etc.). In our view, the concept of “green plastics” should, in addition to biodegradability, encompass biocompatibility as well as a net neutral or positive impact on the environment. Hence, a “green plastic” should be an alternative polymeric material with properties or characteristics that are comparable or superior to those of conventional polymeric materials but that demonstrates less environmental impact. Such plastics can be biobased or fossil-based materials. 98 There has been an increasing and persistent call for rethinking the plastic economy in terms of the future of the environment; the sustainability of civilization; and the pursuit of green(er) chemistry, sustainable chemicals, and a circular economy. 99 − 102 Consequently, research that explores green(er) alternatives to conventional plastic materials has increased. For example, on June 5, 2014, Avantium ( https://www.avantium.com/ ) Technologies, headquartered in Amsterdam (The Netherlands), reportedly reached an agreement with international brands, such as Coca-Cola, Danone, Swire, and others, to produce packages exclusively from 2,5-furandicarboxylic acid (FDCA), a carbohydrate-based material, industrially known as poly(ethylene furanoate) (PEF), which affords many advantages over fossil-based PET, the dominant plastic material employed industry-wide in beverage packaging. 103 The advantages of PEF over PET include a higher gas barrier and better water, thermal, and tensile properties. 101

In recent years, a myriad of green(er) plastics with the potential to replace conventional plastics in various domestic and industrial applications has emerged. For example, nanocellulose has recently gained prominence as a versatile, benign, ubiquitous, and sustainable material that can be modified, spun, drawn, molded, and even cast, finding applications in almost every economic sector and replacing plastics and other conventional materials such as steel. 104 In addition to its abundance, nanocellulose has been demonstrated to represent a green(er) alternative to plastics used in, among others, the packaging industry, membrane fabrication, and composites with properties and characteristics comparable to and even exceeding those of conventional plastics in terms of resilience, lightweight, and strength. 105 As nanocellulose research and development advances, it is hoped that nanocellulose will replace conventional plastic materials in many domestic and industrial applications to promote our SDGs. The increasing number of green(er) alternatives to conventional plastics, such as DNA biodegradable materials, 106 lignin biodegradable and biocompatible composite films, 107 chitin biocompatible and biodegradable plastics and fibers, 108 , 109 biocompatible and nontoxic plastics derived from lactic acid, 110 is a testament to the promising technologies available to mitigate plastic pollution. In a yet-to-be-published work, we demonstrate that bamboo straws are not only green(er) than plastic straws but also sustainable and do not negatively impact the environment. We also posit that other green(er) articles, such as tires, shoes, and clothing, may become possible in the near future with concerted effort and political will.

5.3. Revision of Extended Producer Responsibility (EPR)

As previously noted, in too many cases, the cost of pollution is considered tolerable in terms of a narrow cost–benefit analysis; thus, the negative impact of plastic pollution on, among others, our ecosystem and health, with a cost of more than USD 2 trillion per annum is usually under-reported. 47 , 111 Moreover, because most of the plastic debris generated inland generally finds its way into aquatic ecosystems, the oceans are one of the environments worst hit by plastic pollution, with an estimated impact of over USD 1 trillion per annum in terms of the loss in ocean productivity. 112 As pointed out by Forrest et al., 47 the current extended producer responsibility (EPR) and other plastic-related laws must be reviewed to reflect the exigency of the threat posed by plastic pollution; moreover, “voluntary” financial contributions from entities throughout the value chain of the plastic economy would generate considerable funds for innovative waste management schemes and environmental remediation. The goal of a circular plastic economy will remain elusive unless processes and technologies exist that ensure that the recycling of waste plastic is economically viable; 47 to promote the realization of a circular plastic economy, such technologies and processes must not only be cost-competitive but also enable the production of high-purity monomers (that are comparable to virgin resins) from waste plastic recovered from the environment. 113 , 114 As long as plastic recycling is disincentivized by its high cost, realizing and sustaining a circular plastic economy will be expensive, which is one of the major reasons that stakeholders in the plastic economy value chain have not fully embraced the concept of a circular plastic economy despite the recognized benefits. 115 Furthermore, we suggest that tariffs and levies on reclaimed or recycled plastic goods and materials should be reviewed throughout the value chain to promote their economic viability and enable them to compete with products produced from virgin resins, thus encouraging businesses to engage in environmental remediation. In addition, policies should be formulated to encourage consumers to use reusable and recycled products, thus incentivizing the reclamation of plastic wastes.

Elsewhere, we have argued 2 that despite the potential benefits of a circular economy, such as job creation, infrastructure development, and a low-carbon economy, we do not foresee the realization of a sustainable circular plastic economy without the cooperation of policymakers, governments, and the population. Hence, the synergistic cooperation of all stakeholders is imperative to plastic pollution mitigation.

6. Conclusions

Pollution is a global phenomenon and no nation or continent is immune to its negative environmental impact. Plastic pollution, in particular, is hazardous to the living and nonliving components of the environment. The negative impact of macro-, micro-, and nanoplastics on the environment and living organisms results from a combination of inherent characteristics and toxicity, the leaching of additives or constituent compounds, and the release of persistent sorbed pollutants. Although studies concerning the impact of plastic matter on various ecosystems, such as soil and air, are limited, the available literature demonstrates the exigency of revisiting the entire plastic economy value chain to ensure a sustainable environment.

To meaningfully address this global challenge, the scientific community must take ownership of the environmental challenges in which it is complicit as well as a remedial action. The political will of governments, cooperation of stakeholders, and determination of the population are imperative to the success of plastic pollution mitigation. Although plastics have contributed immensely to the progress and advancement of our civilization, we must ensure that posterity inherits sustainable earth. The time for action is now.

7. Future Prospects

Plastic pollution is a global phenomenon that exacerbates global warming and flooding and must be mitigated to achieve environmental sustainability. While plastic pollution presents a serious environmental threat, numerous opportunities exist that can be harnessed to mitigate, manage, and control this global problem. However, our understanding of plastic pollution is incomplete and further investigation is required to fully elucidate this problem. For example, studies on the accumulation of plastic debris as sediment in water beds (e.g., ocean floors), as a result of the phenomenon of convergence caused by the persistent directional flow of surface water, need to be investigated. We argue that (with the exception of polyethylene, polypropylene, and expanded polystyrene) a significant portion of plastic debris, such as polyesters, rubber particles, polyurethanes, PET, poly(vinyl chloride), linear low-density polyethylene, and high-density polyethylene, with specific gravities exceeding 1 g/cm 3 , sink to the bottom of the oceans. It is necessary to investigate whether these plastic particles undergo biodegradation and are biocompatible with the life forms inhabiting the ocean floors. The degradation pathways or processes of these plastic materials in the absence of light and oxygen, which are the conditions that exist at ocean floors, must be determined. Do these plastic materials resist anaerobic degradation processes on the ocean floor? What is the impact of free volume or molecular impermeability on the chemical and biological resistance of these plastics? The composition of ocean beds is not easy to study; however, modified nuclear microscopy and micro-Fourier transform infrared (FTIR) mapping may facilitate such investigations. In addition, understanding the degradation pathways of nanoplastics may reveal ways to break plastic materials down into their constituent chemical compounds that can be captured and reused. 116 It is, furthermore, necessary to elucidate the biochemical kinetics and interactions of polymeric systems (e.g., plastic and rubber), their degradation pathways in living systems, the possible risk they pose to living organisms, and their potential to cause living cell mutations and physiological changes. Finally, facile and inexpensive sensors must be developed to monitor our consumables, such as food and water, for plastic debris. A real-time monitoring system of water distribution networks would enable governments to protect water resources and the health of their populations by preventing people from ingesting harmful amounts of plastic materials. However, what amount of plastic constitutes a harmful amount of plastic for an average human is unclear. Perhaps medical science can determine this amount.

Acknowledgments

The authors (SSR and AOCI) thank the Council for Scientific and Industrial Research (HGER74p) and the Department of Science and Innovation (HGERA8x) for financial support.

Author Contributions

⊥ A.O.C.I. and S.S.R. contributed equally to this work.

The authors declare no competing financial interest.

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Pollution is the introduction of harmful materials into the environment. These harmful materials are called pollutants.

Biology, Ecology, Health, Earth Science, Geography

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Pollution is the introduction of harmful materials into the environment . These harmful materials are called pollutants . Pollutants can be natural, such as volcanic ash . They can also be created by human activity, such as trash or runoff produced by factories. Pollutants damage the quality of air, water, and land. Many things that are useful to people produce pollution. Cars spew pollutants from their exhaust pipes. Burning coal to create electricity pollutes the air. Industries and homes generate garbage and sewage that can pollute the land and water. Pesticides —chemical poisons used to kill weeds and insects— seep into waterways and harm wildlife . All living things—from one-celled microbes to blue whales—depend on Earth ’s supply of air and water. When these resources are polluted, all forms of life are threatened. Pollution is a global problem. Although urban areas are usually more polluted than the countryside, pollution can spread to remote places where no people live. For example, pesticides and other chemicals have been found in the Antarctic ice sheet . In the middle of the northern Pacific Ocean, a huge collection of microscopic plastic particles forms what is known as the Great Pacific Garbage Patch . Air and water currents carry pollution. Ocean currents and migrating fish carry marine pollutants far and wide. Winds can pick up radioactive material accidentally released from a nuclear reactor and scatter it around the world. Smoke from a factory in one country drifts into another country. In the past, visitors to Big Bend National Park in the U.S. state of Texas could see 290 kilometers (180 miles) across the vast landscape . Now, coal-burning power plants in Texas and the neighboring state of Chihuahua, Mexico have spewed so much pollution into the air that visitors to Big Bend can sometimes see only 50 kilometers (30 miles). The three major types of pollution are air pollution , water pollution , and land pollution . Air Pollution Sometimes, air pollution is visible . A person can see dark smoke pour from the exhaust pipes of large trucks or factories, for example. More often, however, air pollution is invisible . Polluted air can be dangerous, even if the pollutants are invisible. It can make people’s eyes burn and make them have difficulty breathing. It can also increase the risk of lung cancer . Sometimes, air pollution kills quickly. In 1984, an accident at a pesticide plant in Bhopal, India, released a deadly gas into the air. At least 8,000 people died within days. Hundreds of thou sands more were permanently injured. Natural disasters can also cause air pollution to increase quickly. When volcanoes erupt , they eject volcanic ash and gases into the atmosphere . Volcanic ash can discolor the sky for months. After the eruption of the Indonesian volcano of Krakatoa in 1883, ash darkened the sky around the world. The dimmer sky caused fewer crops to be harvested as far away as Europe and North America. For years, meteorologists tracked what was known as the “equatorial smoke stream .” In fact, this smoke stream was a jet stream , a wind high in Earth’s atmosphere that Krakatoa’s air pollution made visible. Volcanic gases , such as sulfur dioxide , can kill nearby residents and make the soil infertile for years. Mount Vesuvius, a volcano in Italy, famously erupted in 79, killing hundreds of residents of the nearby towns of Pompeii and Herculaneum. Most victims of Vesuvius were not killed by lava or landslides caused by the eruption. They were choked, or asphyxiated , by deadly volcanic gases. In 1986, a toxic cloud developed over Lake Nyos, Cameroon. Lake Nyos sits in the crater of a volcano. Though the volcano did not erupt, it did eject volcanic gases into the lake. The heated gases passed through the water of the lake and collected as a cloud that descended the slopes of the volcano and into nearby valleys . As the toxic cloud moved across the landscape, it killed birds and other organisms in their natural habitat . This air pollution also killed thousands of cattle and as many as 1,700 people. Most air pollution is not natural, however. It comes from burning fossil fuels —coal, oil , and natural gas . When gasoline is burned to power cars and trucks, it produces carbon monoxide , a colorless, odorless gas. The gas is harmful in high concentrations , or amounts. City traffic produces highly concentrated carbon monoxide. Cars and factories produce other common pollutants, including nitrogen oxide , sulfur dioxide, and hydrocarbons . These chemicals react with sunlight to produce smog , a thick fog or haze of air pollution. The smog is so thick in Linfen, China, that people can seldom see the sun. Smog can be brown or grayish blue, depending on which pollutants are in it. Smog makes breathing difficult, especially for children and older adults. Some cities that suffer from extreme smog issue air pollution warnings. The government of Hong Kong, for example, will warn people not to go outside or engage in strenuous physical activity (such as running or swimming) when smog is very thick.

When air pollutants such as nitrogen oxide and sulfur dioxide mix with moisture, they change into acids . They then fall back to earth as acid rain . Wind often carries acid rain far from the pollution source. Pollutants produced by factories and power plants in Spain can fall as acid rain in Norway. Acid rain can kill all the trees in a forest . It can also devastate lakes, streams, and other waterways. When lakes become acidic, fish can’t survive . In Sweden, acid rain created thousands of “ dead lakes ,” where fish no longer live. Acid rain also wears away marble and other kinds of stone . It has erased the words on gravestones and damaged many historic buildings and monuments . The Taj Mahal , in Agra, India, was once gleaming white. Years of exposure to acid rain has left it pale. Governments have tried to prevent acid rain by limiting the amount of pollutants released into the air. In Europe and North America, they have had some success, but acid rain remains a major problem in the developing world , especially Asia. Greenhouse gases are another source of air pollution. Greenhouse gases such as carbon dioxide and methane occur naturally in the atmosphere. In fact, they are necessary for life on Earth. They absorb sunlight reflected from Earth, preventing it from escaping into space. By trapping heat in the atmosphere, they keep Earth warm enough for people to live. This is called the greenhouse effect . But human activities such as burning fossil fuels and destroying forests have increased the amount of greenhouse gases in the atmosphere. This has increased the greenhouse effect, and average temperatures across the globe are rising. The decade that began in the year 2000 was the warmest on record. This increase in worldwide average temperatures, caused in part by human activity, is called global warming . Global warming is causing ice sheets and glaciers to melt. The melting ice is causing sea levels to rise at a rate of two millimeters (0.09 inches) per year. The rising seas will eventually flood low-lying coastal regions . Entire nations, such as the islands of Maldives, are threatened by this climate change . Global warming also contributes to the phenomenon of ocean acidification . Ocean acidification is the process of ocean waters absorbing more carbon dioxide from the atmosphere. Fewer organisms can survive in warmer, less salty waters. The ocean food web is threatened as plants and animals such as coral fail to adapt to more acidic oceans. Scientists have predicted that global warming will cause an increase in severe storms . It will also cause more droughts in some regions and more flooding in others. The change in average temperatures is already shrinking some habitats, the regions where plants and animals naturally live. Polar bears hunt seals from sea ice in the Arctic. The melting ice is forcing polar bears to travel farther to find food , and their numbers are shrinking. People and governments can respond quickly and effectively to reduce air pollution. Chemicals called chlorofluorocarbons (CFCs) are a dangerous form of air pollution that governments worked to reduce in the 1980s and 1990s. CFCs are found in gases that cool refrigerators, in foam products, and in aerosol cans . CFCs damage the ozone layer , a region in Earth’s upper atmosphere. The ozone layer protects Earth by absorbing much of the sun’s harmful ultraviolet radiation . When people are exposed to more ultraviolet radiation, they are more likely to develop skin cancer, eye diseases, and other illnesses. In the 1980s, scientists noticed that the ozone layer over Antarctica was thinning. This is often called the “ ozone hole .” No one lives permanently in Antarctica. But Australia, the home of more than 22 million people, lies at the edge of the hole. In the 1990s, the Australian government began an effort to warn people of the dangers of too much sun. Many countries, including the United States, now severely limit the production of CFCs. Water Pollution Some polluted water looks muddy, smells bad, and has garbage floating in it. Some polluted water looks clean, but is filled with harmful chemicals you can’t see or smell. Polluted water is unsafe for drinking and swimming. Some people who drink polluted water are exposed to hazardous chemicals that may make them sick years later. Others consume bacteria and other tiny aquatic organisms that cause disease. The United Nations estimates that 4,000 children die every day from drinking dirty water. Sometimes, polluted water harms people indirectly. They get sick because the fish that live in polluted water are unsafe to eat. They have too many pollutants in their flesh. There are some natural sources of water pollution. Oil and natural gas, for example, can leak into oceans and lakes from natural underground sources. These sites are called petroleum seeps . The world’s largest petroleum seep is the Coal Oil Point Seep, off the coast of the U.S. state of California. The Coal Oil Point Seep releases so much oil that tar balls wash up on nearby beaches . Tar balls are small, sticky pieces of pollution that eventually decompose in the ocean.

Human activity also contributes to water pollution. Chemicals and oils from factories are sometimes dumped or seep into waterways. These chemicals are called runoff. Chemicals in runoff can create a toxic environment for aquatic life. Runoff can also help create a fertile environment for cyanobacteria , also called blue-green algae . Cyanobacteria reproduce rapidly, creating a harmful algal bloom (HAB) . Harmful algal blooms prevent organisms such as plants and fish from living in the ocean. They are associated with “ dead zones ” in the world’s lakes and rivers, places where little life exists below surface water. Mining and drilling can also contribute to water pollution. Acid mine drainage (AMD) is a major contributor to pollution of rivers and streams near coal mines . Acid helps miners remove coal from the surrounding rocks . The acid is washed into streams and rivers, where it reacts with rocks and sand. It releases chemical sulfur from the rocks and sand, creating a river rich in sulfuric acid . Sulfuric acid is toxic to plants, fish, and other aquatic organisms. Sulfuric acid is also toxic to people, making rivers polluted by AMD dangerous sources of water for drinking and hygiene . Oil spills are another source of water pollution. In April 2010, the Deepwater Horizon oil rig exploded in the Gulf of Mexico, causing oil to gush from the ocean floor. In the following months, hundreds of millions of gallons of oil spewed into the gulf waters. The spill produced large plumes of oil under the sea and an oil slick on the surface as large as 24,000 square kilometers (9,100 square miles). The oil slick coated wetlands in the U.S. states of Louisiana and Mississippi, killing marsh plants and aquatic organisms such as crabs and fish. Birds, such as pelicans , became coated in oil and were unable to fly or access food. More than two million animals died as a result of the Deepwater Horizon oil spill. Buried chemical waste can also pollute water supplies. For many years, people disposed of chemical wastes carelessly, not realizing its dangers. In the 1970s, people living in the Love Canal area in Niagara Falls, New York, suffered from extremely high rates of cancer and birth defects . It was discovered that a chemical waste dump had poisoned the area’s water. In 1978, 800 families living in Love Canal had to a bandon their homes. If not disposed of properly, radioactive waste from nuclear power plants can escape into the environment. Radioactive waste can harm living things and pollute the water. Sewage that has not been properly treated is a common source of water pollution. Many cities around the world have poor sewage systems and sewage treatment plants. Delhi, the capital of India, is home to more than 21 million people. More than half the sewage and other waste produced in the city are dumped into the Yamuna River. This pollution makes the river dangerous to use as a source of water for drinking or hygiene. It also reduces the river’s fishery , resulting in less food for the local community. A major source of water pollution is fertilizer used in agriculture . Fertilizer is material added to soil to make plants grow larger and faster. Fertilizers usually contain large amounts of the elements nitrogen and phosphorus , which help plants grow. Rainwater washes fertilizer into streams and lakes. There, the nitrogen and phosphorus cause cyanobacteria to form harmful algal blooms. Rain washes other pollutants into streams and lakes. It picks up animal waste from cattle ranches. Cars drip oil onto the street, and rain carries it into storm drains , which lead to waterways such as rivers and seas. Rain sometimes washes chemical pesticides off of plants and into streams. Pesticides can also seep into groundwater , the water beneath the surface of the Earth. Heat can pollute water. Power plants, for example, produce a huge amount of heat. Power plants are often located on rivers so they can use the water as a coolant . Cool water circulates through the plant, absorbing heat. The heated water is then returned to the river. Aquatic creatures are sensitive to changes in temperature. Some fish, for example, can only live in cold water. Warmer river temperatures prevent fish eggs from hatching. Warmer river water also contributes to harmful algal blooms. Another type of water pollution is simple garbage. The Citarum River in Indonesia, for example, has so much garbage floating in it that you cannot see the water. Floating trash makes the river difficult to fish in. Aquatic animals such as fish and turtles mistake trash, such as plastic bags, for food. Plastic bags and twine can kill many ocean creatures. Chemical pollutants in trash can also pollute the water, making it toxic for fish and people who use the river as a source of drinking water. The fish that are caught in a polluted river often have high levels of chemical toxins in their flesh. People absorb these toxins as they eat the fish. Garbage also fouls the ocean. Many plastic bottles and other pieces of trash are thrown overboard from boats. The wind blows trash out to sea. Ocean currents carry plastics and other floating trash to certain places on the globe, where it cannot escape. The largest of these areas, called the Great Pacific Garbage Patch, is in a remote part of the Pacific Ocean. According to some estimates, this garbage patch is the size of Texas. The trash is a threat to fish and seabirds, which mistake the plastic for food. Many of the plastics are covered with chemical pollutants. Land Pollution Many of the same pollutants that foul the water also harm the land. Mining sometimes leaves the soil contaminated with dangerous chemicals. Pesticides and fertilizers from agricultural fields are blown by the wind. They can harm plants, animals, and sometimes people. Some fruits and vegetables absorb the pesticides that help them grow. When people consume the fruits and vegetables, the pesticides enter their bodies. Some pesticides can cause cancer and other diseases. A pesticide called DDT (dichlorodiphenyltrichloroethane) was once commonly used to kill insects, especially mosquitoes. In many parts of the world, mosquitoes carry a disease called malaria , which kills a million people every year. Swiss chemist Paul Hermann Muller was awarded the Nobel Prize for his understanding of how DDT can control insects and other pests. DDT is responsible for reducing malaria in places such as Taiwan and Sri Lanka. In 1962, American biologist Rachel Carson wrote a book called Silent Spring , which discussed the dangers of DDT. She argued that it could contribute to cancer in humans. She also explained how it was destroying bird eggs, which caused the number of bald eagles, brown pelicans, and ospreys to drop. In 1972, the United States banned the use of DDT. Many other countries also banned it. But DDT didn’t disappear entirely. Today, many governments support the use of DDT because it remains the most effective way to combat malaria. Trash is another form of land pollution. Around the world, paper, cans, glass jars, plastic products, and junked cars and appliances mar the landscape. Litter makes it difficult for plants and other producers in the food web to create nutrients . Animals can die if they mistakenly eat plastic. Garbage often contains dangerous pollutants such as oils, chemicals, and ink. These pollutants can leech into the soil and harm plants, animals, and people. Inefficient garbage collection systems contribute to land pollution. Often, the garbage is picked up and brought to a dump, or landfill . Garbage is buried in landfills. Sometimes, communities produce so much garbage that their landfills are filling up. They are running out of places to dump their trash. A massive landfill near Quezon City, Philippines, was the site of a land pollution tragedy in 2000. Hundreds of people lived on the slopes of the Quezon City landfill. These people made their living from recycling and selling items found in the landfill. However, the landfill was not secure. Heavy rains caused a trash landslide, killing 218 people. Sometimes, landfills are not completely sealed off from the land around them. Pollutants from the landfill leak into the earth in which they are buried. Plants that grow in the earth may be contaminated, and the herbivores that eat the plants also become contaminated. So do the predators that consume the herbivores. This process, where a chemical builds up in each level of the food web, is called bioaccumulation . Pollutants leaked from landfills also leak into local groundwater supplies. There, the aquatic food web (from microscopic algae to fish to predators such as sharks or eagles) can suffer from bioaccumulation of toxic chemicals. Some communities do not have adequate garbage collection systems, and trash lines the side of roads. In other places, garbage washes up on beaches. Kamilo Beach, in the U.S. state of Hawai'i, is littered with plastic bags and bottles carried in by the tide . The trash is dangerous to ocean life and reduces economic activity in the area. Tourism is Hawai'i’s largest industry . Polluted beaches discourage tourists from investing in the area’s hotels, restaurants, and recreational activities. Some cities incinerate , or burn, their garbage. Incinerating trash gets rid of it, but it can release dangerous heavy metals and chemicals into the air. So while trash incinerators can help with the problem of land pollution, they sometimes add to the problem of air pollution. Reducing Pollution Around the world, people and governments are making efforts to combat pollution. Recycling, for instance, is becoming more common. In recycling, trash is processed so its useful materials can be used again. Glass, aluminum cans, and many types of plastic can be melted and reused . Paper can be broken down and turned into new paper. Recycling reduces the amount of garbage that ends up in landfills, incinerators, and waterways. Austria and Switzerland have the highest recycling rates. These nations recycle between 50 and 60 percent of their garbage. The United States recycles about 30 percent of its garbage. Governments can combat pollution by passing laws that limit the amount and types of chemicals factories and agribusinesses are allowed to use. The smoke from coal-burning power plants can be filtered. People and businesses that illegally dump pollutants into the land, water, and air can be fined for millions of dollars. Some government programs, such as the Superfund program in the United States, can force polluters to clean up the sites they polluted. International agreements can also reduce pollution. The Kyoto Protocol , a United Nations agreement to limit the emission of greenhouse gases, has been signed by 191 countries. The United States, the world’s second-largest producer of greenhouse gases, did not sign the agreement. Other countries, such as China, the world’s largest producer of greenhouse gases, have not met their goals. Still, many gains have been made. In 1969, the Cuyahoga River, in the U.S. state of Ohio, was so clogged with oil and trash that it caught on fire. The fire helped spur the Clean Water Act of 1972. This law limited what pollutants could be released into water and set standards for how clean water should be. Today, the Cuyahoga River is much cleaner. Fish have returned to regions of the river where they once could not survive. But even as some rivers are becoming cleaner, others are becoming more polluted. As countries around the world become wealthier, some forms of pollution increase. Countries with growing economies usually need more power plants, which produce more pollutants. Reducing pollution requires environmental, political, and economic leadership. Developed nations must work to reduce and recycle their materials, while developing nations must work to strengthen their economies without destroying the environment. Developed and developing countries must work together toward the common goal of protecting the environment for future use.

How Long Does It Last? Different materials decompose at different rates. How long does it take for these common types of trash to break down?

• Paper: 2-4 weeks
• Orange peel: 6 months
• Milk carton: 5 years
• Plastic bag: 15 years
• Tin can: 100 years
• Plastic bottle: 450 years
• Glass bottle: 500 years
• Styrofoam: Never

Indoor Air Pollution The air inside your house can be polluted. Air and carpet cleaners, insect sprays, and cigarettes are all sources of indoor air pollution.

Light Pollution Light pollution is the excess amount of light in the night sky. Light pollution, also called photopollution, is almost always found in urban areas. Light pollution can disrupt ecosystems by confusing the distinction between night and day. Nocturnal animals, those that are active at night, may venture out during the day, while diurnal animals, which are active during daylight hours, may remain active well into the night. Feeding and sleep patterns may be confused. Light pollution also indicates an excess use of energy. The dark-sky movement is a campaign by people to reduce light pollution. This would reduce energy use, allow ecosystems to function more normally, and allow scientists and stargazers to observe the atmosphere.

Noise Pollution Noise pollution is the constant presence of loud, disruptive noises in an area. Usually, noise pollution is caused by construction or nearby transportation facilities, such as airports. Noise pollution is unpleasant, and can be dangerous. Some songbirds, such as robins, are unable to communicate or find food in the presence of heavy noise pollution. The sound waves produced by some noise pollutants can disrupt the sonar used by marine animals to communicate or locate food.

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Testing pollution haven and pollution halo hypotheses for Turkey: a new perspective

• Research Article
• Published: 10 June 2020
• Volume 27 , pages 32933–32943, ( 2020 )

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• Mehmet Mert 1 &
• Abdullah Emre Caglar 1  

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In this study, we analyzed the asymmetric short- and long-run causal links between foreign direct investments and emissions in Turkey over the time period 1974–2018. Using hidden co-integration techniques, we defined and tested the asymmetric pollution haven and asymmetric pollution halo hypotheses. To evaluate the long-run asymmetric causal relationship, we estimated both the crouching error correction model and vector error correction model. We performed a stepwise regression model to estimate the crouching error correction model. The empirical results confirmed an asymmetric causal relationship between positive shocks of foreign direct investments and positive movements in emissions in the short run as well as an asymmetric causal link between negative and positive shocks of foreign direct investments and positive emissions in the long run. Furthermore, the results showed that increases in foreign direct investments led to a decrease in the rate of emission growth in both the short and long run. This finding supports the validity of the asymmetric pollution halo hypothesis in Turkey’s case. Policymakers should strengthen their environmental protection laws to protect the quality of their environments as well as implement policies that encourage the use of clean technology and tax incentives that increase foreign direct investment inflows.

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Introduction

Environmental degradation has undoubtedly proven to be one of the most important problems humanity must face in the twenty-first century. Anthropogenic greenhouse gases represent an important source of environmental degradation. Since the beginning of the Industrial Revolution in the eighteenth century, fossil fuel usage has increased CO 2 levels from about 280 parts per million (ppm) in pre-industrial times to about 387 ppm at the beginning of this century and further to 400 ppm now, according to the National Oceanic and Atmospheric Administration (NOAA) Annual Greenhouse Gas Index (Boden et al. 2009 ; Butler and Montzka 2019 ). Carbon emissions (CO 2 ) are known to represent the most significant contributor to recent climate change (Cai et al. 2018 ). Global energy-related carbon emissions increased by 1.7% in 2018, the highest growth rate since 2013 (IEA 2018 ). Why do countries not reduce CO 2 emissions despite international agreements to do so such as the Kyoto Protocol and the Paris Agreement? In other words, why have CO 2 emissions increased recently? According to a study by the Center for Global Development, developing countries account for 63% of the current CO 2 emissions (Center for Global Development 2015 ). In addition, the Clean Development Mechanism established under the Kyoto Protocol does not require developing countries to curtail their emissions that result from trade activities, while industrialized countries must reduce their emissions to a certain level to comply with the Protocol. This effect is confirmed in the United Nations Conference on Trade and Development (UNCTAD) 2019 report, which stated that “annual carbon emissions have accelerated in developing countries and have stabilized in developed countries” (UNCTAD 2019 ).

The Kyoto Protocol drew attention to trade activities in developing countries, which view foreign direct investment (FDI) as an important strategy for economic growth. FDI inflows to the developing countries have increased, especially in the last three decades, due to increased globalization and the free movement of capital. Developing countries cannot allocate sufficient resources to investments that will contribute to economic development to achieve their growth targets. Therefore, FDI can provide some of the resources required. FDI can assist in a country’s development through technology transfer, improved productivity, new management skills, and infrastructure developments. Although FDI contributes to economic growth in the host country, it also raises controversy about environmental quality. The environmental economics literature approaches this question through two opposing hypotheses. The first, the pollution haven hypothesis, states that pollution-intensive production activities are directed from developed countries to those with more lax environmental regulations through FDI. Thus, developed economies reduce the costs of adapting to environmental regulations and benefit from a cheap labor force. The other hypothesis, known as the pollution halo hypothesis, claims that companies from the investing developed countries contribute to the host country’s reduction of emissions because their production structure relies on green technology, unlike the host country’s existing production.

Since the second half of the twentieth century, developed countries have imported many products from developing countries and in this way exported their CO 2 emissions to the developing countries (Peters and Hertwich 2008 ). Developed economies ultimately seek to keep the global temperature rise below 2 ° C. Thus, the developed countries transferred 16 Gt CO 2 emissions to the developing countries between 1990 and 2008 through international trade (Peters et al. 2011 ). In Turkey, a developing country, both CO 2 emissions and FDI inflows increased during the same period (World Bank 2019 ). The EY Attractiveness Survey Europe 2019 named Turkey Europe’s 7th most popular international investment destination in 2018. FDI in Turkey increased 209 billion dollars, more than tenfold the original amount, between the years 2003 and 2018 (Central Bank of the Republic of Turkey 2019 ). BP ( 2019 ) confirms that Turkey emitted 209.9 million tons of CO 2 in 2003, which had increased to 389.9 million tons by 2018. Turkey seems to be quite far from their emission targets in both the Kyoto Protocol and the Paris Agreement. Turkey’s capability to reduce their CO 2 emissions will also play an important role in their EU membership process. Thus, deeply investigating the effect of FDI on CO 2 emissions is essential for Turkish policymakers. Therefore, we believe that use of advanced econometric techniques to investigate the effect of FDI on CO 2 emissions in Turkey not only assists in guiding Turkey’s environmental policy but also provides an important contribution to the environmental economics literature as a whole.

This study examines the asymmetric impact of FDI on Turkey’s CO 2 emissions between the years 1974 and 2018. In this context, this study aims mainly to asymmetrically analyze the relationship between FDI and CO 2 emissions in the short as well as long run, as opposed to the existing literature which examines these links symmetrically, as both FDI and CO 2 can react differently to random shocks. For example, a negative shock in a host country may cause some companies to believe that the situation is temporary, deciding to maintain their position and continue their investments in that country. However, some companies do not want to take the risks associated with the negative situation and may withdraw their investments. Similarly, emissions can increase or decrease due to shocks. For instance, while some countries choose to restrict emissions through protective policies, others avoid serious measures due to economic losses from negative shocks. Therefore, analyzing each of these variables’ disparate reactions to positive versus negative shocks strengthens the validity of the research. In this context, our study distinguishes the asymmetric effects of shocks on the short- and long-term relationships between the variables.

To the best of our knowledge, the pollution halo/haven hypotheses have only been tested symmetrically. However, negative and the positive shocks can affect pollution differently. With this in mind, we obtained the negative and the positive cumulative shocks of FDI and CO 2 emissions for Turkey. After analyzing short-run asymmetric causality by using the negative and positive cumulative shocks, we performed hidden co-integration techniques drawn from Granger and Yoon ( 2002 ), and Hatemi-J and Irandost ( 2012 ) to test the asymmetric pollution halo and haven hypotheses in Turkey. The hidden co-integration methodology allows researchers to evaluate relationships between the positive and negative cumulative shocks of the series. The hidden co-integration procedure uses the cumulative shocks of the variables to allow estimation of long-run asymmetric relationships between the series. By estimating the crouching error correction model (CECM) after performing Granger and Yoon’s ( 2002 ) hidden co-integration test and the vector error correction model (VECM) after performing Hatemi-J and Irandost( 2012 ) hidden co-integration test, we estimated the short-run relationships between the cumulative positive and negative shocks of the variables. Furthermore, we defined the long-run asymmetric causality between the variables based on the error correction models.

This study contributes to the literature in the following ways: firstly, by asymmetrically testing both the pollution halo and haven hypotheses. Secondly, it investigates the long-run asymmetric causality through the estimation of the error correction model. Finally, it proposes stepwise regression to estimate the CECM drawn from Mert and Caglar’s ( 2019 ) study. An examination of the literature reveals that no more than four lags are usually incorporated in the crouching error correction model as it is too computationally intensive to add more (see Honarvar 2009 ; Alom and Ritson 2012 ; Alexakis et al. 2013 ; Koutroulis et al. 2016 ). However, the crouching error correction model may possess more than 4 lags. This discrepancy may lead to omitted variable bias in the studies. To correct for such bias, we thus suggest stepwise regression to select the lags in the crouching error correction model initially proposed by Mert and Caglar ( 2019 ), thus providing a methodological contribution to the literature. In this way, this study provides a new perspective in the ongoing debate about the FDI-emission relationship.

The next section of the study presents a review of the current literature on the pollution haven and pollution halo hypotheses. “Data and methods” describes the data and econometric methodology of the study. “Findings” presents empirical findings, and “Discussion” concludes the study.

Literature review

The relationship between environmental degradation and FDI inflows has become a popular topic of discussion in environmental economics. The current literature presents two opposing hypotheses examining the impact of FDI on environmental degradation. The first, the well-known pollution haven hypothesis, posits that global companies outsource pollution-intensive industries to countries with cheap labor and lax environmental regulations. These countries, which do not possess the resources necessary for economic development, instead depend on external investments. They rely on legislative incentives to encourage FDI. This hypothesis is partially explained by Grossman and Krueger’s ( 1991 ) scale effect, which postulates that countries need more natural resources and inputs in the first stage of economic growth. Thus, FDI-led growth in the first stage of economic development should lead to more environmental pollution. Zhang and Zhou ( 2016 ) found that FDI inflows could enhance the host country’s economic activities, which triggers an increase in environmental pollution if the lax regulations of the host countries are not changed. On the contrary, the pollution halo hypothesis posits that multinational companies transfer new production processes, management skills, and greener technologies to the host country by complying with the international environmental standard framework, thus contributing to a reduction in carbon emissions of the host country.

An examination of the current literature investigating the effect of FDI on environmental degradation reveals the importance of country selection in the studies. While some studies consider individual countries, others analyze country groups. Shahbaz’s ( 2015 ) work serves as a pioneer for the literature on the FDI-emission links; as previous work had proven that this relationship changes by country groups (i.e., low, middle, and upper countries, etc.), his study demonstrated the pollution haven hypothesis is more strongly supported in low- and middle-income countries, while the pollution halo hypothesis appears more valid in high-income countries. Table 1 presents a summary of several studies that investigated whether FDI causes environmental pollution in the host country through various econometric methods.

Contradictory views frequently occur in the literature, especially in studies that focus on FDI and environmental pollution. While some studies support the pollution haven hypothesis (Akbostancı et al. 2007 ; Kivyiro and Arminen ( 2014 ); Seker et al. 2015 ; Solarin et al. 2017 ; Gorus and Aslan 2019 ; Caglar 2020 ), others find stronger evidence for the pollution halo hypothesis (Hao and Liu 2015 ; Mert and Boluk 2016 ; Rafindadi et al. 2018 ; Balsalobre-Lorente et al. 2019 ). In addition, some studies (Lee 2013 ; Shaari et al. 2014 ) demonstrate that the neutrality hypothesis is more appropriate for explaining the relationship between these two variables. Studies examining the FDI-emission link in Turkey employ both the standard ARDL and the Johansen and Maki structural breaks co-integration tests. Table 1 shows that the pollution haven hypothesis is more strongly supported in all the studies focusing on Turkey except in Ozturk and Oz ( 2016 ). In general, criteria such as country selection, data length, and econometric method play a key role in the difference in results. The FDI-emission literature relies most frequently on co-integration and causality analysis such as ARDL co-integration and Granger causality. Our study examines the short- and long-term asymmetric causality for the FDI-CO 2 emission relationship in Turkey. We use the Hatemi-J ( 2012 ) asymmetric causality test for short-term analysis, while we employ both the Granger and Yoon ( 2002 ) and Hatemi-J and Irandost ( 2012 ) hidden co-integration approaches, which, to the best of our knowledge, have not yet been used in the relevant literature, for long-term causality.

Data and methods

We obtained the 1974–2018 time series of carbon dioxide (CO 2 ) emissions (metric tons per capita) from BP statistics and the net foreign direct investment (current US$) series (FDI) from the World Bank online database over the same time period. We used different data sources for each series since the series FDI was available on World Bank database until 2018, but its emission series only ran until 2014. We used the natural logarithms of both series for analysis. To obtain the natural logarithm of the FDI series, we added a constant value to the series so that all its values were positive.

We firstly performed unit root tests to analyze the stationarities of both series, employing the Phillips-Perron (PP) (Phillips and Perron 1988 ) and Ng-Perron (Ng-P) tests (Ng and Perron 2001 ). Furthermore, to analyze the structural breaks in the series, we used the Zivot and Andrews (ZA) unit root test ( 1992 ), which allows one structural break in the series, as well as the Narayan and Popp ( 2010 ) unit root (NP) test, which allows two structural breaks.

To study the short-run asymmetric causal relationships between the series, we employed the Hatemi-J ( 2012 , HJ) test. According to the standard procedure for this test, we could write the series as Eqs. 1 and 2 if the series are I ( 1 ):

In Eqs. 1 and 2 , CO 20 and FDI 0 represent initial values, while series ε 1 t and ε 2 t are white noise. The positive and negative shocks of the series are represented as \( {\varepsilon}_{1i}^{+}=\max \left({\varepsilon}_{1i},0\right) \) , \( {\varepsilon}_{2i}^{+}=\max \left({\varepsilon}_{2i},0\right) \) , \( {\varepsilon}_{1i}^{-}=\min \left({\varepsilon}_{1i},0\right) \) , and \( {\varepsilon}_{2i}^{-}=\min \left({\varepsilon}_{2i},0\right) \) (Nasir et al. 2020 ). Decomposing these shocks allows them to be rewritten as \( {\varepsilon}_{1i}={\varepsilon}_{1i}^{+}+{\varepsilon}_{1i}^{-} \) and \( {\varepsilon}_{2i}={\varepsilon}_{2i}^{+}+{\varepsilon}_{2i}^{-} \) . The cumulative positive and negative shocks of the series could be represented as in Eqs. 3 – 6 :

According to the HJ test procedure, the cumulative shocks are then represented as a VAR model with p lags. The lag p is a lag in a VAR model that meets all stability conditions; it is determined by criteria such as AIC or SC. The HJ test uses a Wald test statistic (W-stat.) to test asymmetric causality between the cumulative shocks with bootstrap-critical values (Hatemi-J 2012 ).

The asymmetric pollution halo and the asymmetric pollution haven hypotheses are defined in Table 2 , which assumes FDI shocks are independent variables, whereas CO 2 shocks are assumed to serve as the dependent variables in the long-run equations. Furthermore, the coefficients for the shocks of FDI in the equations are assumed to be statistically significant. Thus, eight different equations could be obtained to test asymmetric hypotheses by the end of the procedure.

The pollution haven hypothesis claims that foreign direct investments lead to increased emissions, while the pollution halo hypothesis posits that the foreign direct investments lead to a decline in emissions. Thus, for cases 1 and 3 in Table 2 , any shock (positive or negative) to foreign direct investments leads to an increase in the positive movements of emissions, thus confirming the validity of the asymmetric pollution haven hypothesis in those cases. In cases 6 and 8 in the table, any shock to the foreign direct investments induces a decrease in emission decrease. This means that the shocks of the foreign direct investments will brake on emission downturn. Thus, the asymmetric pollution haven hypothesis would be valid in cases 6 and 8. However, in cases 2 and 4, any shock to foreign direct investments causes a decline in emission growth. That is, the shocks of the foreign direct investments will brake on emission rises. Consequently, cases 2 and 4 would support the asymmetric pollution halo hypothesis. According to cases 5 and 7, any shock to foreign direct investments causes an increase in emission decline. Thus, foreign direct investment shocks should lead to a downturn in emissions, providing evidence for the validity of the asymmetric pollution halo hypothesis.

To reveal long-run asymmetric relationships between the series, we performed hidden co-integration techniques by Granger and Yoon ( 2002 ) and Hatemi-J and Irandost ( 2012 ). These procedures use the cumulative shocks represented in Eqs. 3 – 5 as the variables in the long-run and short-run equations. Granger and Yoon’s ( 2002 ) hidden co-integration employs Engle and Granger’s ( 1987 ) co-integration technique while Hatemi-J and Irandost ( 2012 ) use the Johansen ( 1996 ) vector error correction models (VECMs) to derive the long- and short-run equations. To evaluate the long-run asymmetric causal relationship between the cumulative shocks, we estimated the crouching error correction model (CECM) after performing Granger and Yoon’s ( 2002 ) hidden co-integration test and estimated the VECM after performing Hatemi-J and Irandost ( 2012 ) hidden co-integration test.

We performed the PP and Ng-P tests to analyze the unit root of the series. The results of these tests can be seen in Table 3 . They show that the levels of the CO 2 and FDI series are non-stationary, but their first differences are stationary.

In addition to the PP and Ng-P tests, we performed ZA and NP tests to check for the presence of any significant structural breaks in the series. Ordinary unit root tests such as PP and Ng-P cannot reject the unit root null hypothesis as they do not consider structural breaks. If significant structural breaks exist in the series, ordinary unit root tests can find the series to be non-stationary even if it is stationary. Thus, to ensure a more robust decision about the existence of a unit root in a series, the unit root tests with structural breaks should be performed after the ordinary unit root tests, especially if ordinary root tests find that the series is non-stationary. Table 4 provides the results of these unit root tests with structural breaks. According to these results, the unit root hypothesis cannot be rejected; thus, we conclude that no significant structural breaks in the series exist.

From these unit root test results, we concluded that the series CO 2 and FDI are I ( 1 ), so the HJ test can be performed to estimate the short-run asymmetric causal relationship. To do so, we obtain the cumulative shocks of the series given in Eqs. 3 – 5 . The lag value is determined from the VAR model, which meets all the stability conditions based on the AIC statistic. The HJ test results can be seen in Table 5 .

As seen from the results in Table 5 , we found an asymmetric causality from the positive shocks of foreign direct investments to positive shocks of emissions. In other words, positive shocks to foreign direct investment cause positive shocks to the emissions in the short run. These results indicate that emission reduction policies that rely on FDI will actually induce increased CO 2 emissions in the short run in Turkey. Thus, policymakers in Turkey must employ long-term policies to achieve the emissions targets. In addition, this study examines long-term relationships between FDI and CO 2 emissions to guide policymakers in forming long-term policies.

To estimate long-run asymmetric causal relationships between the series, we performed the Granger and Yoon ( 2002 ) hidden co-integration (GY) test based on the co-integration procedure from Engle and Granger ( 1987 ). We began by performing unit root tests for positive and negative cumulative shock series given in Eqs. 3 – 5 , concluding that all the cumulative shocks were I ( 1 ). These results are not shown here to conserve space. We then performed a GY test for the functions \( {\mathrm{CO}}_2^{+}=f\left({\mathrm{FDI}}^{+}\right) \) , \( {\mathrm{CO}}_2^{+}=f\left({\mathrm{FDI}}^{-}\right) \) , \( {\mathrm{CO}}_2^{-}=f\left({\mathrm{FDI}}^{+}\right) \) , and \( {\mathrm{CO}}_2^{-}=f\left({\mathrm{FDI}}^{-}\right) \) with model A (model with intercept) and model C (model with intercept and trend). With the GY test, we found a co-integration only for the function \( {\mathrm{CO}}_2^{+}=f\left({\mathrm{FDI}}^{+}\right) \) with model C. This result is shown in Table 6 .

According to the Z -statistic given in Table 6 , the series are co-integrated at the .10 level if the series \( {\mathrm{CO}}_2^{+} \) is a dependent variable in the long-run equation. These long-run estimation results can be seen in Table 6 . The residuals of this long-run estimation are normally distributed. We tested the normality of the residuals with the Jarque-Bera test. We also calculated a HAC variance-covariance matrix to correct any possible heteroscedasticity or autocorrelation in residuals. The long-run estimation results demonstrate that all coefficients are statistically significant. The coefficient of FDI + is − 0.221, which corresponds to the second case in Table 2 and means that a 1% increase in the positive shocks of the foreign direct investments will decrease the positive shocks of emissions by 0.221%. In other words, the positive improvements in the foreign direct investments will lead to a decrease in emission increase. This result supports the validity of the asymmetric pollution halo hypothesis in Turkey, confirming that FDI inflows contribute to Turkey’s emissions targets. Policymakers who focus on environmental standards should thus encourage more investors to invest in Turkey through economic incentives such as tax breaks.

To estimate the CECM, Eqs. 7 and 8 can be derived as below (Granger and Yoon 2002 ):

In Eqs. 7 and 8 , \( {\hat{\varepsilon}}_{t-1} \) represents the one-lagged residuals of the estimated long-run equation in Table 6 . The coefficients ψ 1 and γ 1 represent the long-run adjustments, while the coefficients of the lagged differenced variables stand for the short-run adjustments. Many studies, like Granger and Yoon ( 2002 ) and Honarvar ( 2009 ), only report the significant coefficients resulting from these CECM equations. To obtain equations with the significant coefficients, stepwise regression is performed in the current study. We set the maximum lag value (the value of k and p ) at 10 and applied the stepwise regression with backward selection at the .10 significance level to estimate the parameters of the CECM equations that are statistically significant at the .10 level. The results of this estimation are given in Table 7 .

In the short-run equations given in Table 7 , all coefficients are significant at the .10 level because of the stepwise regression procedure. Gonzalo and Granger ( 1995 ) defined the dependent variable of the CECM equation with an insignificant error correction coefficient as a permanent component. Permanent component variables are responsible for the long-run dynamics between the variables. Any shock to the permanent component will affect both itself and the other variables in the long run. On the contrary, a dependent variable in the CECM equation with a significant error correction coefficient is defined as transitory (Gonzalo and Granger 1995 ). A transitory variable will not determine long-run dynamics; thus, any shock to the transitory variable will be impermanent in the long run. The results in Table 7 demonstrate that the coefficient of error correction is insignificant for the short-run equation of FDI + and the coefficient of error correction is negative and significant (coef. =−0.68 and P < .10) as expected for the short-run equation of \( {\mathrm{CO}}_2^{+} \) ; thus, the series FDI + is a permanent component while the series \( {\mathrm{CO}}_2^{+} \) is transitory in the long run. Positive shocks in foreign direct investments determine long-run dynamics. These results demonstrate that an asymmetric long-run causality from FDI + to \( {\mathrm{CO}}_2^{+} \) . Furthermore, in the equation of the emissions, the coefficient of foreign direct investment is negative and significant (coef. =−0.50 and P < .10) in Table 7 . Thus, a positive movement in foreign direct investments will lead to a decrease in the growth rate of emissions in the short run. This result parallels the results of the long-run equation. In both the short and long runs, policymakers should aim to encourage FDI in Turkey.

We also analyzed hidden co-integration between the series with the Hatemi-J and Irandost ( 2012 ) VCEM methodology to obtain robust results. For this purpose, we estimated VECM models for the functions \( {\mathrm{CO}}_2^{+}=f\left({\mathrm{FDI}}^{+}\right) \) , \( {\mathrm{CO}}_2^{+}=f\left({\mathrm{FDI}}^{-}\right) \) , \( {\mathrm{CO}}_2^{-}=f\left({\mathrm{FDI}}^{+}\right) \) , and \( {\mathrm{CO}}_2^{-}=f\left({\mathrm{FDI}}^{-}\right) \) . We used the model with only an intercept in the co-integration equation (CE) and no intercept in VAR, the model with an intercept in CE and VAR and the model with intercept, and trend in CE and no trend in VAR. We only found a co-integration relationship for the function \( {\mathrm{CO}}_2^{+}=f\left({\mathrm{FDI}}^{-}\right) \) with the model intercept in CE and VAR; the lag value was determined as 6 by using AIC and BIC statistics. In this VECM estimation, no serial correlation or heteroscedasticity existed and the residuals were normally distributed. The estimation results of VECM(6) can be seen in Table 8 .

In the long-run estimation as seen in Table 8 , the coefficient of the series FDI − is insignificant (Coef. = −0.9505 and t -stat. = 1.28 ( P > .10)) so we cannot conclude that either the asymmetric pollution haven or the pollution halo hypothesis is valid. However, the coefficient of the error correction in the short-run equation is negative and significant (Coef. = −0.06 and t -stat. = − 2.39 ( P < .05)). This negative and significant error correction coefficient means that there is an asymmetric long-run causality from the negative shocks of the foreign direct investments to the positive shocks of emissions. Despite the insignificant effects of the negative movements of FDI in the long run, the effect of the negative movements of FDI on the positive movements of emissions is negative and significant in the short run (Coef. = − 0.443 and t = − 2.31 ( P < .05)). Furthermore, the coefficient of error correction term is close to zero (Coef. = −0.06), thus demonstrating the slow speed to reach the equilibrium (long-run) level. Short-run imbalances will be adjusted by 0.06% within the first year, but reaching long-run level will require about 17 years. Thus, the significant effects of FDI − on \( {\mathrm{CO}}_2^{+} \) in the short run will become insignificant after a long time. As a result, the short-run regulations in foreign direct investments also play an important role in reaching emission targets for Turkey.

In this study, we test the asymmetric pollution halo and asymmetric pollution haven hypotheses for Turkey by using the data from 1974–2018. We estimate short- and long-run asymmetric causal relationships between the positive and the negative movements in foreign direct investments and emissions. We perform hidden co-integration techniques and estimate vector and crouching error correction models. We finally perform stepwise regression to estimate crouching error correction models and define the long-run asymmetric causality based on the error correction models.

The unit root process indicated that the foreign direct investments and emissions series in Turkey are both non-stationary. This result is consistent with the findings in Akbostancı et al. ( 2007 ), Mutafoglu ( 2012 ), Seker et al. ( 2015 ), Ozturk and Oz ( 2016 ), Koçak and Şarkgüneşi ( 2018 ), and Terzi and Pata ( 2019 ). The unit roots of these series signify their lack of resistance to a given random shock; their level will not reach the ex-level in the long run. These findings indicate that Turkey can form policies on foreign direct investments to decrease its levels of emissions.

The short-run causality results indicate an asymmetric causal link between positive shocks in foreign direct investments and positive movements in emissions \( \left({\mathrm{FDI}}^{+}\to {\mathrm{CO}}_2^{+}\right) \) . In the long run, positive shocks in foreign direct investments are asymmetrically causally related to positive movements in emissions \( \left({\mathrm{FDI}}^{+}\to {\mathrm{CO}}_2^{+}\right) \) while negative shocks in foreign direct investments also demonstrate an asymmetrical causal relationship with positive movements in emissions \( \left({\mathrm{FDI}}^{-}\to {\mathrm{CO}}_2^{+}\right) \) . Consequently, any shock (positive or negative) to foreign direct investments in Turkey will also determine emission growth in the long run, while positive shocks in foreign direct investments in Turkey will determine emission growth in the short run. From this perspective, policies on both short- and long-run foreign direct investments should determine the emission targets in Turkey.

The result of hidden co-integration analyses indicates that \( \left[{\mathrm{FDI}}^{+},{\mathrm{CO}}_2^{+}\right] \) and \( \left[{\mathrm{FDI}}^{-},{\mathrm{CO}}_2^{+}\right] \) are co-integrated. In Turkey, positive movements in both foreign direct investments and emissions act in tandem, whereas negative movements in foreign direct investments and positive movements in emissions move together in the long run. Thus, Turkey could effectively reach its emissions target by implementing FDI policies.

This study mainly contributes to the literature by testing the asymmetric pollution haven and the asymmetric pollution halo hypotheses. The hidden co-integration analyses we performed demonstrate the validity of the asymmetric pollution halo hypothesis in Turkey, therefore signifying that increases in foreign direct investments in Turkey will lead to a decline in emission growth in the long run. This result contradicts the studies by Akbostancı et al. ( 2007 ), Mutafoglu ( 2012 ), Seker et al. ( 2015 ), Kocak and Şarkgunesi ( 2018 ), and Terzi and Pata ( 2019 ), which support the pollution haven hypothesis for Turkey, although those studies tested the pollution hypotheses symmetrically, rather than asymmetrically like this study.

We also estimated the crouching error correction model. To the best of our knowledge, all previous studies have set the maximum lag number as 4 in the literature because higher lag numbers would require too much time to solve the model. This study also contributes to the literature by using stepwise regression to more easily estimate the parameters in the crouching error correction model even with high lag numbers based on the study by Mert and Caglar ( 2019 ). The results of these estimations indicate that foreign direct investments are permanent while emissions are transitory in the long run. Thus, foreign direct investments are responsible for the long-run dynamics, and a shock to foreign direct investments in Turkey will affect both its future value as well as that of emissions.

Our study then contributed to the current literature by concluding that positive movements in foreign direct investments asymmetrically cause positive long-run movements in emissions. Policymakers should take note of the finding that the series FDI + is a permanent component and responsible for long-run dynamics in the decline in emission growth. As well, the CECM results show that the positive movements of the foreign direct investments negatively and significantly impact the positive movements of emissions in the short run. In addition to these findings, the VECM estimation results also demonstrate that the negative movements in foreign direct investments asymmetrically cause positive movements of emissions in the long run; further, negative movements in foreign direct investments negatively and significantly affect the positive movements of emissions in the short run.

When implementing policies to encourage FDI inflows in Turkey, policymakers should implement the following environmentally friendly policies: encouraging investors to import green technology, prioritizing FDI inflows that will ensure environmental protection and economic development, and privileging investors who will contribute to meeting Turkey’s emission reduction targets. Importantly, this study also shows that any movement (positive or negative) of FDI is the main determinant for a decline in the rate of emissions growth in Turkey. As a result, Turkey should attempt to enhance FDI inflows to achieve its emission reduction targets. Authorities should develop policies aimed at not only increasing FDI inflows in Turkey but also protecting the environment in both the short and long runs. Since the global COVID-19 outbreak can be considered an effective shock to FDI as well as other important variables, it will affect Turkey’s ability to protect the environment in both the short and long term. Since our study’s findings provide evidence that FDI inflows impact emissions, Turkey’s policymakers should be prepared for the possible scenarios that may result from this epidemic.

Given the increasing strength of inter-country relations in an ever more global world, future studies seeking to explore the FDI-emission relationship should focus on unions such as the OECD, EU, G20, and MENA. New studies on this relationship should consider the asymmetric effects of FDI for these countries with common characteristics. These studies should examine cross-section dependency, which may play an important role in the relationship between FDI flows and CO 2 emissions.

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This study was supported by the Scientific Research Projects Coordination Unit of Akdeniz University in Turkey. (Project Number: SBG-2020-5189).

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Mert, M., Caglar, A.E. Testing pollution haven and pollution halo hypotheses for Turkey: a new perspective. Environ Sci Pollut Res 27 , 32933–32943 (2020). https://doi.org/10.1007/s11356-020-09469-7

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A study highlights the potential impact of traffic-related air pollution (no2) on attentional development.

A growing body of research shows that exposure to air pollution, especially during pregnancy and childhood, may have a negative impact on brain development. Now a study led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by the "la Caixa" Foundation, has found that exposure to nitrogen dioxide (NO 2 ) during the first two years of life is associated with poorer attention capacity in children aged 4 to 8, especially in boys. NO 2 is a pollutant that comes mainly from traffic emissions.

The study, published in Environment International , shows that higher exposure to NO 2 was associated with poorer attentional function in 4- to 6-year-olds, with increased susceptibility to this pollutant observed in the second year of life. This association persisted at an age of 6 to 8 years of age only in boys, with a slightly greater susceptibility period from birth to 2 years of age.

The researchers used data from 1,703 women and their children from the INMA Project birth cohorts in four Spanish regions. Using the home address, the researchers estimated daily residential exposure to NO 2 during pregnancy and the first 6 years of childhood. In parallel, they assessed the attentional function (the ability to choose what to pay attention to and what to ignore) at 4-6 years and 6-8 years, and working memory (the ability to temporarily hold information) at 6-8 years, using validated computerised tests.

Periods of higher susceptibility to air pollution

A previous INMA study reported that exposure to NO 2 during pregnancy and childhood was associated with impaired attentional function in children at 4-5 years of age. The present study found that:

• Higher exposure to NO 2 between 1.3 and 1.6 years of age was associated with higher hit reaction time standard error, an indicator of speed consistency, in the attentional function test at 4-6 years of age.
• Higher exposure to NO 2 between 1.5 and 2.2 years of age was associated with more omission errors.
• Higher exposure to NO 2 between 0.3 and 2.2 years was associated with higher hit reaction time standard error at 6-8 years only in boys.
• No associations were found between higher exposure to NO 2 and working memory in children aged 6 to 8 years.

"These findings underline the potential impact of increased traffic-related air pollution on delayed development of attentional capacity and highlight the importance of further research into the long-term effects of air pollution in older age groups," explains Anne-Claire Binter , last author of the study and postdoctoral researcher at ISGlobal.

As the brain matures

Attentional function is crucial for the development of the brain's executive functions, which manage and control actions, thoughts and emotions to achieve a goal or purpose. "The prefrontal cortex, a part of the brain responsible for executive functions, develops slowly and it is still maturing during pregnancy and childhood," adds Binter. This makes it vulnerable to exposure to air pollution, which has been linked in animal studies to inflammation, oxidative stress, and impaired energy metabolism in the brain.

"In boys, the association between exposure to N0 2 and attentional function may last longer because their brains mature more slowly, which could make them more vulnerable," she points out. To understand this better, future studies should follow people over time to see how age and gender affect the relationship between air pollution and attention span, especially in older age groups.

In conclusion, "this study suggests that early childhood, up to the age of 2, seems to be a relevant period for implementing preventive measures," says Binter. "Even a small effect at the individual level from relatively low levels of exposure, as in this study, can have large consequences at the population level. Exposure to traffic-related air pollution is therefore a determinant of the health of future generations."

• Intelligence
• Child Development
• Learning Disorders
• Air Quality
• Air Pollution
• Environmental Issues
• Air pollution
• Automobile emissions control
• Mercury poisoning
• Early childhood education
• Fossil fuel
• Familiarity increases liking

Story Source:

Materials provided by Barcelona Institute for Global Health (ISGlobal) . Note: Content may be edited for style and length.

Journal Reference :

• Kellie L.H.A. Crooijmans, Carmen Iñiguez, Kristina W. Withworth, Marisa Estarlich, Aitana Lertxundi, Ana Fernández-Somoano, Adonina Tardón, Jesús Ibarluzea, Jordi Sunyer, Mònica Guxens, Anne-Claire Binter. Nitrogen dioxide exposure, attentional function, and working memory in children from 4 to 8 years: Periods of susceptibility from pregnancy to childhood . Environment International , 2024; 186: 108604 DOI: 10.1016/j.envint.2024.108604

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‘sustainable fashion’ needs a breakthrough. here’s a blueprint for it.

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Breakthrough, by Dr Camilla Pang

Fashion is an odd industry. Not much of how it works makes sense. Products are designed by people who don't know how they're made and made by people who have little influence over what they're making despite being manufacturing experts.

Most fashion business models rely on outdated forecasting models and arbitrary minimum order quantities; winter products enter shops in summer and vice versa. A significant volume of clothes produced are never sold (due to overproduction, tied to minimum order quantities) and so are incinerated or shredded for low-grade material uses, like stuffing mattresses.

This business model has been economically sustainable for brands by outsourcing manufacturing to factories in developing countries (often based on third-party audits–not site visits). 'Outsourcing' means brands procure finished products from garment manufacturers, who conduct materials sourcing, product R&D and development on behalf of the brands. Brand involvement is typically the approval of samples, price negotiation and order placement. But this approach is no longer 'sustainable' in social, economic, or environmental terms, and procuring products without knowing where and how they are made is becoming more risky than ever. Just this week, the Ecodesign for Sustainable Products Regulation (ESPR) was adopted in Europe , and a facet of this will be a digital product passport (DPP) for every textile product sold on the EU market, containing detailed materials, design and production data, as well as recycling instructions.

Today's fashion industry operates fractured, dividing the brand (the 'creative') from production (the 'technical'). The arbiters of the industry–designers–have long been educated to uphold their 'vision' and aesthetic tendencies at the expense of all else, and they are at the top of the food chain when it comes to conceiving products that drive company revenue. But designers (and buyers) in the Global North make these decisions without knowledge of the consequences on those producing them, mostly in the Global South. The industry needs a Breakthrough to unite and meet the regulatory, environmental, and social challenges ahead, and today, a tome launched that could reframe how the industry works to enable that.

Illustration of 'Observation', by Dr Camilla Pang

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Dr Camilla Pang is a scientist and the author of Explaining Humans. In a video interview, she explained how her new book, Breakthrough , helps problem-solving by applying scientific thinking to daily challenges, including creative ones. "The scientific process isn't just about being technical. It's actually a very fluid, messy, and creative process of design and personal expression, as well as using [scientific] methods. Much like a designer, you have to design experiments and consider the different nuances [of them]". "Designers can be creative and technical–it's not a zero-sum game," she says.

But educators tend to disagree, as does society, and, more often than not, industry: "this is the indoctrination we're taught in schools; you're either technical, or creative–a myth that this book helps us dispel". That myth, at least in part, is what stands between fashion designers and fashion producers, with designers taught to see technical constraints as 'compromising their vision' and technicians powerless in the industry's hierarchy.

In Breakthrough , Dr Pang reinterprets the established scientific process through her own 'non-linear' way of thinking and working, powered by her neurodivergence (she has Autism Spectrum Disorder (ASD) and ADHD). Breakthrough lays out how to think like a (creative) scientist, learn how to fail, and embrace the unknown, but what can fashion professionals learn from it?

Firstly, Observation is the starting point of every major scientific discovery. Observations of a process or problem "are sparks, lighting the fire of an idea to pursue, a hypothesis to test, a theory to develop, and a conclusion to hone," according to Dr Pang. For the fashion industry, Observation must start with observing how products are made and their ingredients–the process where an idea becomes a physical product. Yet most fashion designers have never been to a textile mill or garment factory–it's not part of the training for designers to experience industrial production. Therefore, they have never seen the process that their designs or product choices determine.

Dr Pang believes this lack of Observation is disempowering, preventing designers from fully engaging their creativity. It's inconceivable to her that she would design an experiment and not conduct it. Consider a nurse training and working without ever entering a hospital or medical facility: it's inconceivable. Yet designers choose chemical processes that are toxic or dangerous to industry workers because they haven't Observed them or learned about them.

For fashion products, textile production accounts for the most significant portion of the footprint within the production phase, and design decisions determine the textile types and processes used. To address the design and technical disconnect, Dr Pang suggests brands' introduce "programs, internships or placements" in factories for designers to observe the production processes, enabling designers to begin hypothesizing about how to design with inherent sustainability based on a foundation of knowledge of the products' ingredients and methods. Far from a compromise, this will hand the power to create 'better' to a generation of designers coming through the ranks and who expect their employers to prioritize sustainability. To this end, Dr Pang shares a cautionary tale: "Barclays boycott is one example," she says, where 220 university students declared a " career boycott" of the bank due to its climate policies, which include the ongoing financing of fossil fuel companies; the students' response was: 'we'll take our talents elsewhere, permanently'.

Recently, I accompanied two Gen Z 'voices' on a trip to garment factories in Bangladesh and Vietnam as part of the Puma Voices of a RE:GENERATION program. The 'voices' included food content creator Luke Jaque-Rodney, who examined garment worker lives from their factory to home kitchens in Stitch and Spice ; and visual artist Jade Roche who documented the environmental consequences of industrialization and fashion's role in this through Made in Vietnam and Made in Bangladesh . Their Observations changed their understanding of the industry and garment workers' lives, debunking stereotypes they had learned at home in Europe. Observation is powerful, but it also challenges the status quo.

Illustration of 'Hypothesis', by Dr Camilla Pang

On the journey to problem-solving and discovery, Breakthrough explains that after Observation comes a Hypothesis, or "how to come up with ideas." Dr Pang interviewed science peers for her book, and they explained how they see hypotheses as forming creative narratives, like crime books that solve the mystery by observing clues and then working out which questions to ask–the hypotheses. Breakthrough offers the 'unputdownable thriller' as a perfect product of Observation and hypotheses, but what might be fashion's equivalent? The 'untakeoffable' jean? How does 'coming up with ideas' lead to the perfect (and in this case, sustainable) end-product?

The hypothesis, Dr Pang explains, is something to "build ideas upon and sharpen them against". Far from being a linear process where you observe, hypothesise, test and share findings, it's far more chaotic and iterative. To use the crime clue analogy, the clues lead to questions, and the answers lead to more questions and possibly a rearrangement of the clues to view them from a different angle and ask more questions. Perhaps the perfect jean is one where every ingredient and process is a clue that must be rearranged to ask the question: what is the impact, utility and commercial desirability of this combination? If it's not optimal, it's time to rearrange and hypothesise again.

Hypothesis might really come into its own for fashion soon, with unprecedented data demands in the new European Union Ecodesign regulation, which will require individual product-level data on product materials, design, disassembly instructions and recyclability (as part of the digital product passports). The hypothesis stage allows all these requirements to be probed as a system based on the full production process documented during Observation. A designer without Observation and subsequent Hypothesis will be without the tools and inquisition to pursue Ecodesign compliance; and that failure could be expensive.

Breakthrough presents Focus as the next critical step in the scientific method to decide which lines of inquiry to pursue (to solve product sustainability problems, in this case). Dr Pang gives the metaphor of the nut to be cracked and two possible approaches: the obvious and quick one (the hammer), or the indirect and slow one (the dissolving solution that melts the shell, allowing time to contemplate how the shell 'works' and what that might mean for the nut in their co-dependent' system). Fashion and any industry or individual favoring short-term thinking is choosing the hammer, obviously.

Illustration of 'Focus', by Dr Camilla Pang

In fashion, an example is choosing a 'lower emission' raw material like organic in place of conventional cotton and ignoring the subsequent synthetic dyestuffs and textile treatment required to make the final fabric. "Simply applying the most obvious solution may give you the feeling of progress, but it isn't necessarily getting you anywhere," says Dr Pang. In science, Focus can amount to untangling a mess of information, which can give valuable insights if "wrestled into a more manageable form", she says.

Breakthrough explains that this wrangling needs a system, a set of rules, and a way of grouping the data into clusters so it can be more easily visualized. Instead of designing a product based on indiscriminate decisions, imagine that every decision belongs to a data cluster, and each cluster can be evaluated to become either an area of Focus, or ignored (based on a rationale, rather than chaos that leads to simply overlooking the information). It's this kind of scientific approach structure that could help fashion designers operate within a design framework, or 'toolkit' of clustered design and product information, that would enable evaluation of how a design could and might be changed, helping to improve product credentials ahead of enforcement (from 2026) of Ecodesign for Sustainable Product Regulations in Europe.

Breakthrough is a treasure trove of guidance for observing, questioning, analyzing, and reinterpreting the fashion industry–extracting ideas and structure from its chaos for better economic, social, and environmental outcomes. Just a first few chapters have been plundered here, but the others, spanning analysis, trouble-shooting failures, collaboration, and how to seek proof and be objective. The book culminates in Imagination: how to build worlds and expand reality.

Dr Pang believes “There's a scientist hidden inside all of us. Science's greatest gift to us is not formulae, but enabling the urge to discover” which is what “makes us truly human”. For humans, the myth that we are either creative or technical, and can remain divided along these lines while trying to solve today’s biggest challenge—environmental and social sustainability—is false and dangerous. Breakthrough offers a blueprint to reframe how to think and solve problems using structure and method; while unleashing creativity and imagination, but they need each other. Not zero-sum, but a sum that’s greater than the parts.

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