1-20 of 25 Results

  • Keywords: pollution x
Clear all


Stormwater Management and Roadways  

Nigel Pickering and Somayeh Nassiri

Nonpoint source pollution is common in highly developed areas worldwide, degrading downstream water quality conditions and causing algal growth, aquatic toxicity, and sometimes fish kills. Stormwater runoff that results from rainfall or snowmelt events creates high-flow runoff from impervious surfaces and adjacent areas transporting multiple pollutants to the receiving waters. Although water quality regulations in the developed world have been effective in cleaning up wastewater discharges, their success with remediating stormwater discharges has not been consistent. An exploration of the sources, characteristics, and treatment of roadway runoff, a type of runoff that can be toxic and more difficult to manage because of the linear nature of the road network, is necessary. Since 1975, there have been more than 50 major roadway studies quantifying the sources and types of runoff contaminants like sediment, metals, inorganic salts, and organic compounds. Vehicle sources of pollutants are considered the most pernicious of all roadway contaminants, with brakes and tires being major sources. In the last decade, the leachate from tire wear particles has been linked to toxicity in coho salmon. Nonstructural stormwater management minimizes contamination by using source controls; for example, the elimination of almost all lead in automotive fuel has reduced roadway lead contamination significantly and the introduction of low-copper brake pads in the United States is expected to reduce roadway copper contamination over time. Structural stormwater management practices treat contaminated roadway runoff using small natural treatment systems; this is due in large part to the linear nature of roadways that makes larger regional systems more difficult. Since 2000, treatment performance has improved; however, there is still a great need for further improvement. Suggestions for treatment improvements include designing with low maintenance in mind; applying machine learning to the existing data; improving the understanding of road-land pollutant dynamics; using a transdisciplinary applied research approach to identify the means to improve treatment and reduce toxicity; improving the media used in treatment systems to enhance performance; improving structural strength of permeable pavement; and increasing implementation by facilitating ways to allow/encourage small, effective, and less costly alternatives.


Agricultural Nitrogen and Phosphorus Pollution in Surface Waters  

Marianne Bechmann and Per Stålnacke

Nutrient pollution can have a negative impact on the aquatic environment, with loss of biodiversity, toxic algal blooms, and a deficiency in dissolved oxygen in surface waters. Agricultural production is one of the main contributors to these problems; this article provides an overview of and background for the main biogeochemical processes causing agricultural nutrient pollution of surface waters. It discusses the main features of the agricultural impact on nutrient loads to surface waters, focusing on nitrogen and phosphorus, and describes some of the main characteristics of agricultural management, including processes and pathways from soil to surface waters. An overview of mitigation measures to reduce pollution, retention in the landscape, and challenges regarding quantification of nutrient losses are also dealt with. Examples are presented from different spatial scales, from field and catchment to river basin scale.


The Environmental History of Russia  

Stephen Brain

Russian environmental history is a new field of inquiry, with the first archivally based monographs appearing only in the last years of the 20th century. Despite the field’s youth, scholars studying the topic have developed two distinct and contrasting approaches to its central question: How should the relationship between Russian culture and the natural world be characterized? Implicit in this question are two others: Is the Russian attitude toward the non-human world more sensitive than that which prevails in the West; and if so, is the Russian environment healthier or more stable than that of the United States and Western Europe? In other words, does Russia, because of its traditional suspicion of individualism and consumerism, have something to teach the West? Or, on the contrary, has the Russian historical tendency toward authoritarianism and collectivism facilitated predatory policies that have degraded the environment? Because environmentalism as a political movement and environmental history as an academic subject both emerged during the Cold War, at a time when the Western social, political, and economic system vied with the Soviet approach for support around the world, the comparative (and competitive) aspect of Russian environmental history has always been an important factor, although sometimes an implicit one. Accordingly, the existing scholarly works about Russian environmental history generally fall into one of two camps: one very critical of the Russian environmental record and the seeming disregard of the Russian government for environmental damage, and a somewhat newer group of works that draw attention to the fundamentally different concerns that motivate Russian environmental policies. The first group emphasizes Russian environmental catastrophes such as the desiccated Aral Sea, the eroded Virgin Lands, and the public health epidemics related to the severely polluted air of Soviet industrial cities. The environmental crises that the first group cites are, most often, problems once prevalent in the West, but successfully ameliorated by the environmental legislation of the late 1960s and early 1970s. The second group, in contrast, highlights Russian environmental policies that do not have strict Western analogues, suggesting that a thorough comparison of the Russian and Western environmental records requires, first of all, a careful examination of what constitutes environmental responsibility.


Monitoring and Modeling of Outdoor Air Pollution  

Stefan Reis

Air pollution has been a major threat to human health, ecosystems, and agricultural crops ever since the onset of widespread use of fossil fuel combustion and emissions of harmful substances into ambient air. As a basis for the development, implementation, and compliance assessment of air pollution control policies, monitoring networks for priority air pollutants were established, primarily for regulatory purposes. With increasing understanding of emission sources and the release and environmental fate of chemicals and toxic substances into ambient air, as well as atmospheric transport and chemical conversion processes, increasingly complex air pollution models have entered the scene. Today, highly accurate equipment is available to measure trace gases and aerosols in the atmosphere. In addition, sophisticated atmospheric chemistry transport models—which are routinely compared to and validated and assessed against measurements—are used to model dispersion and chemical processes affecting the composition of the atmosphere, and the resulting ambient concentrations of harmful pollutants. The models also provide methods to quantify the deposition of pollutants, such as acidifying and eutrophying substances, in vegetation, soils, and freshwater ecosystems. This article provides a general overview of the underlying concepts and key features of monitoring and modeling systems for outdoor air pollution.


Exploring Air Pollution and COVID-19 Linkages in South Asia  

Muthukumara Mani and Takahiro Yamada

South Asia is at the epicenter of the global air pollution problems and still evolving in COVID-19 cases and fatalities. There is growing evidence of increased rates of COVID-19 in areas with high levels of air pollution. Air pollution is found to cause cellular damage and inflammation throughout the body and has been linked to higher rates of diseases, including cancer, heart disease, stroke, diabetes, asthma, and other comorbidities. All these conditions also potentially increase the risk of death in COVID-19 patients. The causal link between the exposure to air pollution and COVID-19 is still under investigation around the world, underpinned by rigorous scientific research and peer-review processes. However, in terms of the approach after a careful review of the literature, the instrumental variable (IV) approach is a prospective candidate to establish causality in a reduced-form analysis to overcome endogeneity and measurement errors of air pollution level. An analysis, therefore, using sufficiently anonymized individual and household level information on COVID-19, household air pollution, and other individual and household socioeconomic endowments in the same primary sampling unit (PSU) of the individual and household survey would be necessary to establish the causality. The PSU data are usually available from demographic health surveys (DHS) with randomly displaced location information to maintain anonymity. Also, for the instrument of the exposure to ambient air pollution, the use of thermal inversions is suggested conditional on weather-related variables—for example, temperature, precipitation, wind velocity and direction, and humidity.


Cultivation, Improvement, and Environmental Impacts of Tea  

Mainaak Mukhopadhyay and Tapan Kumar Mondal

Tea, the globally admired, non-alcoholic, caffeine-containing beverage, is manufactured from the tender leaves of the tea [Camellia sinensis (L.)] plant. It is basically a woody, perennial crop with a lifespan of more than 100 years. Cultivated tea plants are natural hybrids of the three major taxa or species, China, Assam (Indian), or Cambod (southern) hybrids based on the morphological characters (principally leaf size). Planting materials are either seedlings (10–18 months old) developed from either hybrid, polyclonal, or biclonal seeds, or clonal cuttings developed from single-leaf nodal cuttings of elite genotypes. Plants are forced to remain in the vegetative stage as bushes by following cultural practices like centering, pruning, and plucking, and they are harvested generally from the second year onward at regular intervals of 7–10 days in the tropics and subtropics, with up to 60 years as the economic lifespan. Originally, the Chinese were the first to use tea as a medicinal beverage, around 2000 years ago, and today, around half of the world’s population drink tea. It is primarily consumed as black tea (fermented tea), although green tea (non-fermented) and oolong tea (semifermented) are also consumed in many countries. Tea is also used as vegetables such as “leppet tea” in Burma and “meing tea” in Thailand. Green tea has extraordinary antioxidant properties, and black tea plays a positive role in treating cardiovascular ailments. Tea in general has considerable therapeutic value and can cure many diseases. Global tea production (black, green, and instant) has increased significantly during the past few years. China, as the world’s largest tea producer, accounts for more than 38% of the total global production of made tea [i.e. ready to drink tea] annually, while production in India, the second-largest producer. India recorded total production of 1233.14 million kg made tea during 2015–2016, which is the highest ever production so far. Since it is an intensive monoculture, tea cultivation has environmental impacts. Application of weedicides, pesticides, and inorganic fertilizers creates environmental hazards. Meanwhile, insecticides often eliminate the fauna of a vast tract of land. Soil degradation is an additional concern because the incessant use of fertilizers and herbicides compound soil erosion. Apart from those issues, chemical runoff into bodies of water can also create problems. Finally, during tea manufacturing, fossil fuel is used to dry the processed leaves, which also increases environmental pollution.


The Environmental Kuznets Curve  

David I. Stern

The environmental Kuznets curve (EKC) is a hypothesized relationship between environmental degradation and GDP per capita. In the early stages of economic growth, pollution emissions and other human impacts on the environment increase, but beyond some level of GDP per capita (which varies for different indicators), the trend reverses, so that at high income levels, economic growth leads to environmental improvement. This implies that environmental impacts or emissions per capita are an inverted U-shaped function of GDP per capita. The EKC has been the dominant approach among economists to modeling ambient pollution concentrations and aggregate emissions since Grossman and Krueger introduced it in 1991 and is even found in introductory economics textbooks. Despite this, the EKC was criticized almost from the start on statistical and policy grounds, and debate continues. While concentrations and also emissions of some local pollutants, such as sulfur dioxide, have clearly declined in developed countries in recent decades, evidence for other pollutants, such as carbon dioxide, is much weaker. Initially, many understood the EKC to imply that environmental problems might be due to a lack of sufficient economic development, rather than the reverse, as was conventionally thought. This alarmed others because a simplistic policy prescription based on this idea, while perhaps addressing some issues like deforestation or local air pollution, could exacerbate environmental problems like climate change. Additionally, many of the econometric studies that supported the EKC were found to be statistically fragile. Some more recent research integrates the EKC with alternative approaches and finds that the relation between environmental impacts and development is subtler than the simple picture painted by the EKC. This research shows that usually, growth in the scale of the economy increases environmental impacts, all else held constant. However, the impact of growth might decline as countries get richer, and richer countries are likely to make more rapid progress in reducing environmental impacts. Finally, there is often convergence among countries, so that countries that have relatively high levels of impacts reduce them more quickly or increase them more slowly, all else held constant.


The Economics of Marine Plastic Pollution  

Clemens W. Gattringer

Ubiquitous marine plastic pollution has become a prominent ecological issue, as it provokes implications that threaten marine species, induces health concerns, and causes vast economic damages. The complex dynamics behind its pervasive occurrence are multipronged and multidimensional, and simple clear-cut causal chains cannot always be identified. Analytical appraisals aiming to advance the understanding of pervasive plastic pollution need to address these complexities and acknowledge the interconnectedness of social and ecological systems. Orthodox economic analyses have insufficiently addressed this integration and are frequently characterized by shallow transdisciplinary and monodisciplinary approaches. As a result, several mechanisms that are highly relevant in constituting the problem tend to be neglected by presuming simplistic assumptions about human agency and inadequate nature-economy relationships. This reductionism in the conceptualization is mirrored in the policy responses that are advocated to address the issue. A broader perspective and the integration of different disciplinary concepts (such as biophysical limits as a result of the laws of thermodynamics, the notion of power, cognitive biases, institutions, and incommensurability) can underpin a more holistic perspective that considers the issue’s inherent complexities. While in a market idealist world consumers can “vote with their wallets” and transcend their values into purchasing decisions on the market, in reality there are essential difficulties to such an approach. Marine plastic pollution thus challenges economic thinking to address this real-world ecological challenge with insights that are compatible with and noncontradictory to the broad body of knowledge already elaborated by natural sciences. These perspectives are essential not only for forming a substantive interdisciplinary analysis and understanding the underlying institutions of consumption and production, clear key drivers of the problem, but also to identify promising political solutions for meaningful change.


Housing, Indoor Air Pollution, and Health in High-Income Countries  

Richard Sharpe, Nicholas Osborne, Cheryl Paterson, Timothy Taylor, Lora Fleming, and George Morris

Despite the overwhelming evidence that living in poor-quality housing and built environments are significant contributors to public health problems, housing issues persist and represent a considerable societal and economic burden worldwide. The complex interaction between multiple behavioral, lifestyle, and environmental factors influencing health throughout the “life-course” (i.e., from childhood to adulthood) in high-income countries has limited the ability to develop more salutogenic housing interventions. The resultant, usually negative, health outcomes depend on many specific housing factors including housing quality and standards, affordability, overcrowding, the type of tenure and property. The immediate outdoor environment also plays an important role in health and wellbeing at the population level, which includes air (indoor and outdoor), noise pollution and the quality of accessible natural environments. These exposures are particularly important for more vulnerable populations, such as the elderly or infirm, and those living in insecure accommodation or in fuel poverty (i.e., being unable to heat the home adequately). Being homeless also is associated with increased risks in a number of health problems. Investigating pathways to protecting health and wellbeing has led to a range of studies examining the potential benefits resulting from accessing more natural environments, more sustainable communities, and housing interventions such as “green construction” techniques. Built environment interventions focusing on the provision of adequate housing designs that incorporate a “life-course” approach, affordable and environmentally sustainable homes, and urban regeneration along with active community engagement, appear capable of improving the overall physical and mental health of residents. While some interventions have resulted in improved public health outcomes in more high-income countries, others have led to a range of unintended consequences that can adversely affect residents’ health and wellbeing. Furthering understanding into four interrelated factors such as housing-specific issues, the immediate environment and housing, vulnerable populations, and natural spaces and sustainable communities can help to inform the development of future interventions.


Atmospheric Brown Clouds  

Sumit Sharma, Liliana Nunez, and Veerabhadran Ramanathan

Atmospheric brown clouds (ABCs) are widespread pollution clouds that can at times span an entire continent or an ocean basin. ABCs extend vertically from the ground upward to as high as 3 km, and they consist of both aerosols and gases. ABCs consist of anthropogenic aerosols such as sulfates, nitrates, organics, and black carbon and natural dust aerosols. Gaseous pollutants that contribute to the formation of ABCs are NOx (nitrogen oxides), SOx (sulfur oxides), VOCs (volatile organic compounds), CO (carbon monoxide), CH4 (methane), and O3 (ozone). The brownish color of the cloud (which is visible when looking at the horizon) is due to absorption of solar radiation at short wavelengths (green, blue, and UV) by organic and black carbon aerosols as well as by NOx. While the local nature of ABCs around polluted cities has been known since the early 1900s, the widespread transoceanic and transcontinental nature of ABCs as well as their large-scale effects on climate, hydrological cycle, and agriculture were discovered inadvertently by The Indian Ocean Experiment (INDOEX), an international experiment conducted in the 1990s over the Indian Ocean. A major discovery of INDOEX was that ABCs caused drastic dimming at the surface. The magnitude of the dimming was as large as 10–20% (based on a monthly average) over vast areas of land and ocean regions. The dimming was shown to be accompanied by significant atmospheric absorption of solar radiation by black and brown carbon (a form of organic carbon). Black and brown carbon, ozone and methane contribute as much as 40% to anthropogenic radiative forcing. The dimming by sulfates, nitrates, and carbonaceous (black and organic carbon) species has been shown to disrupt and weaken the monsoon circulation over southern Asia. In addition, the ozone in ABCs leads to a significant decrease in agriculture yields (by as much as 20–40%) in the polluted regions. Most significantly, the aerosols (in ABCs) near the ground lead to about 4 million premature mortalities every year. Technological and regulatory measures are available to mitigate most of the pollution resulting from ABCs. The importance of ABCs to global environmental problems led the United Nations Environment Programme (UNEP) to form the international ABC program. This ABC program subsequently led to the identification of short-lived climate pollutants as potent mitigation agents of climate change, and in recognition, UNEP formed the Climate and Clean Air Coalition to deal with these pollutants.


Environmental Regulations in India  

Rama Mohana R Turaga and Anish Sugathan

Pollution is one of the greatest causes of premature deaths and morbidity in the world, and this burden of pollution is disproportionately borne by the lower and middle income countries such as India—home to more than one-sixth of humanity. In India, due to the compound effect of its large population and high levels of environmental pollution, the human cost of pollution is among the highest in the world. The environmental degradation is partly a consequence of the development model pursued after independence in 1947 based on large-scale industrialization and exploitative resource utilization, with scant consideration for sustainability. Moreover, it is also due to the failure of the environmental administration, governance, and regulatory infrastructure to keep pace with the magnitude and pace of economic growth in India since economic liberalization in 1991. Ironically, India was also one of the early pioneers of integrating environmental considerations into its legislative and policy-making process beginning in the early 1970s. The federal and state environmental regulation and policy framing institutions set up during this era, along with environmental legislation such as the Environment (Protection) Act 1986, are comparable in design, stringency, and comprehensiveness to other contemporary command-and-control environmental regulatory regimes in many industrially developed economies. However, the widening gap between de jure expectations of environmental compliance and the de facto state of affairs has been a great concern for environmental governance in the country. The ongoing debates discuss several mechanisms to address the regulatory failures. The first is a greater emphasis on strengthening institutions and mechanisms that foster transparency and public disclosure by pollution sources with the intent to increase access to and credibility of information on pollution. Proponents argue this will help mobilize groups such as non-governmental organizations (NGOs) and the general public to pressure the industry and government to improve regulatory enforcement. Second, there have been calls for wider adoption of market-based instruments that are more efficient than the traditional command-and-control approaches on which India relies. Again, information is a prerequisite for the functioning of such market-based regulatory mechanisms. Third, the legal infrastructure to facilitate expedited hearing of environmental litigation is being created. With the establishment of the National Green Tribunal in 2010, India is one of only three other countries in the world to have an exclusive judicial body to hear environmental cases. This is potentially a significant step in providing greater access to environmental justice. An emerging view, however, argues that the prevailing economic development model is incompatible with ensuring sustainable development and requires a radical rethink.


Economics of Hazardous Waste Management  

Hilary Sigman

Hazardous waste management involves treatment, disposal, or recycling of a wide range of different waste streams from industry, households, and others. The diversity of wastes and management methods means that many choices affect its environmental harms, which result from possible contamination of groundwater, surface water, soil, and air. Efficient public policies that would fully reflect such varied external costs are unlikely to be feasible. In practice, governments principally apply three policy approaches to hazardous waste: taxes on hazardous waste, liability for environmental damages, and standards-based regulation of waste management facilities. Hazardous waste taxes may help internalize environmental costs but do not reflect all the variability in these costs. By contrast, liability for environmental damage can make waste generators and managers confront environmental costs that vary with their particular choices. However, environmental liability is often linked to programs for cleanup of contaminated sites and may not create efficient incentives for active waste management because this liability does not reflect the social costs of the contamination. Regulation usually takes the form of technology and performance standards applied to treatment, storage, and disposal facilities (TSDFs) and affects generation decisions only indirectly. Research finds that public policies that raise costs of hazardous waste management, such as taxes and regulation, encourage less waste generation, but may also provoke detrimental responses. First, facilities may substitute illegal waste dumping for legal management and thus exacerbate environmental damage. Second, generators may ship waste to jurisdictions with weaker environmental protections, especially developing countries, giving rise to a “waste haven” effect. This effect may create offsetting environmental damage, facilitate destructive policy competition among jurisdictions, and worsen inequities in exposure to environmental harm from hazardous waste.


The Oceans and Human Health  

Lora Fleming, Michael Depledge, Niall McDonough, Mathew White, Sabine Pahl, Melanie Austen, Anders Goksoyr, Helena Solo-Gabriele, and John Stegeman

The interdisciplinary study of oceans and human health is an area of increasing global importance. There is a growing body of evidence that the health of the oceans and that of humans are inextricably linked and that how we interact with and affect our oceans and seas will significantly influence our future on earth. Since the emergence of modern humans, the oceans have served as a source of culture, livelihood, expansion, trade, food, and other resources. However, the rapidly rising global population and the continuing alterations of the coastal environment are placing greater pressure on coastal seas and oceans. Negative human impacts, including pollution (chemical, microbial, material), habitat destruction (e.g., bottom trawling, dredging), and overfishing, affect not only ecosystem health, but also human health. Conversely, there is potential to promote human health and well-being through sustainable interactions with the coasts and oceans, such as the restoration and preservation of coastal and marine ecosystems. The study of oceans and human health is inherently interdisciplinary, bringing together the natural and social sciences as well as diverse stakeholder communities (including fishers, recreational users, private enterprise, and policymakers). Reviewing history and policy with regard to oceans and human health, in addition to known and potential risks and benefits, provides insights into new areas and avenues of global cooperation, with the possibility for collaboratively addressing the local and global challenges of our interactions with the oceans, both now and in the future.


Use of Experimental Economics in Policy Design and Evaluation: An Application to Water Resources and Other Environmental Domains  

Simanti Banerjee

Economics conceptualizes harmful effects to the environment as negative externalities that can be internalized through implementation of policies involving regulatory and market-based mechanisms, and behavioral economic interventions. However, effective policy will require knowledge and understanding of intended and unintended stakeholder behaviors and consequences and the context in which the policy will be implemented. This mandate is nontrivial since policies once implemented can be hard to reverse and often have irreversible consequences in the short and/or long run, leading to high social costs. Experimental economics (often in combination with other empirical evaluation methods) can help by testing policies and their impacts prior to modification of current policies, and design and implementation of new ones. Such experimental evaluation can include lab and field experiments, and choice experiments. Additionally, experimental policy evaluation should pay attention to scaling up problems and the ethical ramifications of the treatment. This would ensure that the experimental findings will remain relevant when rolled out to bigger populations (hence retaining policy makers’ interest in the method and evidence generated by it), and the treatment to internalize the externality will not create or exacerbate societal disparities and ethical challenges.


Air Pollution and Weather Interaction in East Asia  

Aijun Ding, Xin Huang, and Congbin Fu

Air pollution is one of the grand environmental challenges in developing countries, especially those with high population density like China. High concentrations of primary and secondary trace gases and particulate matter (PM) are frequently observed in the industrialized and urbanized regions, causing negative effects on the health of humans, plants, and the ecosystem. Meteorological conditions are among the most important factors influencing day-to-day air quality. Synoptic weather and boundary layer dynamics control the dispersion capacity and transport of air pollutants, while the main meteorological parameters, such as air temperature, radiation, and relative humidity, influence the chemical transformation of secondary air pollutants at the same time. Intense air pollution, especially high concentration of radiatively important aerosols, can substantially influence meteorological parameters, boundary layer dynamics, synoptic weather, and even regional climate through their strong radiative effects. As one of the main monsoon regions, with the most intense human activities in the world, East Asia is a region experiencing complex air pollution, with sources from anthropogenic fossil fuel combustion, biomass burning, dust storms, and biogenic emissions. A mixture of these different plumes can cause substantial two-way interactions and feedbacks in the formation of air pollutants under various weather conditions. Improving the understanding of such interactions needs more field measurements using integrated multiprocess measurement platforms, as well as more efforts in developing numerical models, especially for those with online coupled processes. All these efforts are very important for policymaking from the perspectives of environmental protection and mitigation of climate change.


Environmental Degradation: Estimating the Health Effects of Ambient PM2.5 Air Pollution in Developing Countries  

Ernesto Sánchez-Triana, Bjorn Larsen, Santiago Enriquez, and Andreia Costa Santos

Air pollution of fine particulates (PM2.5) is a leading cause of mortality worldwide. It is estimated that ambient PM2.5 air pollution results in between 4.1 million and 8.9 million premature deaths annually. According to the World Bank, the health effects of ambient PM2.5 air pollution had a cost of $6.4 trillion in purchasing power parity (PPP) adjusted dollars in 2019, equivalent to 4.8% of global gross domestic product (PPP adjusted) that year. Estimating the health effects and cost of ambient PM2.5 air pollution involves three steps: (1) estimating population exposure to pollution; (2) estimating the health effects of such exposure; and (3) assigning a monetary value to the illnesses and premature deaths caused by ambient air pollution. Estimating population exposure to ambient PM2,5 has gone from predominantly using ground level monitoring data mainly in larger cities to estimates of nationwide population weighted exposures based on satellite imagery and chemical transport models along with ground level monitoring data. The Global Burden of Disease 2010 (GBD 2010) provided for the first time national, regional and global estimates of exposures to ambient PM2.5. The GBD exposure estimates have also evolved substantially from 2010 to 2019, especially national estimates in South Asia, the Middle East and North Africa, Sub-Saharan Africa and Latin America and the Caribbean. Estimation of health effects of ambient PM2.5 has also undergone substantial developments during the last two decades. These developments involve: i) going from largely estimating health effects associated with variations in daily exposures to estimating health effects of annual exposure; ii) going from estimating all-cause mortality or mortality from broad disease categories (i.e., cardiopulmonary diseases) to estimating mortality from specific diseases; and iii) being able to estimate health effects over a wide range of exposure that reflect ambient and household air pollution exposure levels in low- and middle-income countries. As to monetary valuation of health effects of ambient air pollution, estimates in most low- and middle-income countries still rely on benefit transfer of values of statistical life (VSL) from high-income countries.


Impacts of Megacities on Air Quality: Challenges and Opportunities  

Luisa T. Molina, Tong Zhu, Wei Wan, and Bhola R. Gurjar

Megacities (metropolitan areas with populations over 10 million) and large urban centers present a major challenge for the global environment. Transportation, industrial activities, and energy demand have increased in megacities due to population growth and unsustainable urban development, leading to increasing levels of air pollution that subject the residents to the health risks associated with harmful pollutants, and impose heavy economic and social costs. Although much progress has been made in reducing air pollution in developed and some developing world megacities, there are many remaining challenges in achieving cleaner and breathable air for their residents. As centers of economic growth, scientific advancement, and technology innovation, however, these urban settings also offer unique opportunities to capitalize on the multiple benefits that can be achieved by optimizing energy use, reducing atmospheric pollution, minimizing greenhouse gas emissions, and bringing many social benefits. Realizing such benefits will, however, require strong and wide-ranging institutional cooperation, public awareness, and multi-stakeholder involvement. This is especially critical as the phenomenon of urbanization continues in virtually all countries of the world, and more megacities will be added to the world, with the majority of them located in developing countries. The air quality and emission mitigation strategies of eight megacities—Mexico City, Beijing, Shanghai, Shenzhen, Chengdu, Delhi, Kolkata, and Mumbai—are presented as examples of the environmental challenges experienced by large urban centers. While these megacities share common problems of air pollution due to the rapid growth in population and urbanization, each city has its own unique circumstances—geographical location, meteorology, sources of emissions, human and financial resources, and institutional capacity—to address them. Nevertheless, the need for an integrated multidisciplinary approach to air quality management is the same. Mexico City’s air pollution problem was considered among the worst in the world in the 1980s due to rapid population growth, uncontrolled urban development, and energy consumption. After three decades of implementing successive comprehensive air quality management programs that combined regulatory actions with technological change and were based on scientific, technical, social, and political considerations, Mexico City has made significant progress in improving its air quality; however, ozone and particulate matter are still at levels above the respective Mexican air quality standards. Beijing, Shanghai, Shenzhen, and Chengdu are microcosms of megacities in the People’s Republic of China, with rapid socioeconomic development, expanding urbanization, and swift industrialization since the era of reform and opening up began in the late 1970s, leading to severe air pollution. In 2013, the Chinese government issued the Action Plan for Air Pollution Prevention and Control. Through scientific research and regional coordinated air pollution control actions implemented by the Chinese government authority, the concentration of atmospheric pollutants in several major cities has decreased substantially. About 20% of total megacities’ populations in the world reside in Indian megacities; the population is projected to increase, with Delhi becoming the largest megacity by 2030. The increased demands of energy and transportation, as well as other sources such as biomass burning, have led to severe air pollution. The air quality trends for some pollutants have reduced as a result of emissions control measures implemented by the Indian government; however, the level of particulate matter is still higher than the national standards and is one of the leading causes of premature deaths. The examples of the eight cities illustrate that although most air pollution problems are caused by local or regional sources of emissions, air pollutants are transported from state to state and across international borders; therefore, international coordination and collaboration should be strongly encouraged. Based on the available technical-scientific information, the regulations, standards, and policies for the reduction of polluting emissions can be formulated and implemented, which combined with adequate surveillance, enforcement, and compliance, would lead to progressive air quality improvement that benefits the population and the environment. The experience and the lessons learned from the eight megacities can be valuable for other large urban centers confronting similar air pollution challenges.


Household Air Pollution in Low and Middle Income Countries  

Caroline A. Ochieng, Cathryn Tonne, Sotiris Vardoulakis, and Jan Semenza

Household air pollution from use of solid fuels (biomass fuels and coal) is a major problem in low and middle income countries, where 90% of the population relies on these fuels as the primary source of domestic energy. Use of solid fuels has multiple impacts, on individuals and households, and on the local and global environment. For individuals, the impact on health can be considerable, as household air pollution from solid fuel use has been associated with acute lower respiratory infections, chronic obstructive pulmonary disease, lung cancer, and other illnesses. Household-level impacts include the work, time, and high opportunity costs involved in biomass fuel collection and processing. Harvesting and burning biomass fuels affects local environments by contributing to deforestation and outdoor air pollution. At a global level, inefficient burning of solid fuels contributes to climate change. Improved biomass cookstoves have for a long time been considered the most feasible immediate intervention in resource-poor settings. Their ability to reduce exposure to household air pollution to levels that meet health standards is however questionable. In addition, adoption of improved cookstoves has been low, and there is limited evidence on how the barriers to adoption and use can be overcome. However, the issue of household air pollution in low and middle income countries has gained considerable attention in recent years, with a range of international initiatives in place to address it. These initiatives could enable a transition from biomass to cleaner fuels, but such a transition also requires an enabling policy environment, especially at the national level, and new modes of financing technology delivery. More research is also needed to guide policy and interventions, especially on exposure-response relationships with various health outcomes and on how to overcome poverty and other barriers to wide-scale transition from biomass fuels to cleaner forms of energy.


Soil Sediment Loading and Related Environmental Impacts from Farms  

Vito Ferro

Beyond damage to rainfed agricultural and forestry ecosystems, soil erosion due to water affects surrounding environments. Large amounts of eroded soil are deposited in streams, lakes, and other ecosystems. The most costly off-site damages occur when eroded particles, transported along the hillslopes of a basin, arrive at the river network or are deposited in lakes. The negative effects of soil erosion include water pollution and siltation, organic matter loss, nutrient loss, and reduction in water storage capacity. Sediment deposition raises the bottom of waterways, making them more prone to overflowing and flooding. Sediments contaminate water ecosystems with soil particles and the fertilizer and pesticide chemicals they contain. Siltation of reservoirs and dams reduces water storage, increases the maintenance cost of dams, and shortens the lifetime of reservoirs. Sediment yield is the quantity of transported sediments, in a given time interval, from eroding sources through the hillslopes and river network to a basin outlet. Chemicals can also be transported together with the eroded sediments. Sediment deposition inside a reservoir reduces the water storage of a dam. The prediction of sediment yield can be carried out by coupling an erosion model with a mathematical operator which expresses the sediment transport efficiency of the hillslopes and the channel network. The sediment lag between sediment yield and erosion can be simply represented by the sediment delivery ratio, which can be calculated at the outlet of the considered basin, or by using a distributed approach. The former procedure couples the evaluation of basin soil loss with an estimate of the sediment delivery ratio SDRW for the whole watershed. The latter procedure requires that the watershed be discretized into morphological units, areas having a constant steepness and a clearly defined length, for which the corresponding sediment delivery ratio is calculated. When rainfall reaches the surface horizon of the soil, some pollutants are desorbed and go into solution while others remain adsorbed and move with soil particles. The spatial distribution of the loading of nitrogen, phosphorous, and total organic carbon can be deduced using the spatial distribution of sediment yield and the pollutant content measured on soil samples. The enrichment concept is applied to clay, organic matter, and all pollutants adsorbed by soil particles, such as nitrogen and phosphorous. Knowledge of both the rate and pattern of sediment deposition in a reservoir is required to establish the remedial strategies which may be practicable. Repeated reservoir capacity surveys are used to determine the total volume occupied by sediment, the sedimentation pattern, and the shift in the stage-area and stage-storage curves. By converting the sedimentation volume to sediment mass, on the basis of estimated or measured bulk density, and correcting for trap efficiency, the sediment yield from the basin can be computed.


Ecosystem Services and Human Health  

Elisabet Lindgren and Thomas Elmqvist

Ecosystem services refer to benefits for human societies and well-being obtained from ecosystems. Research on health effects of ecosystem services have until recently mostly focused on beneficial effects on physical and mental health from spending time in nature or having access to urban green space. However, nearly all of the different ecosystem services may have impacts on health, either directly or indirectly. Ecosystem services can be divided into provisioning services that provide food and water; regulating services that provide, for example, clean air, moderate extreme events, and regulate the local climate; supporting services that help maintain biodiversity and infectious disease control; and cultural services. With a rapidly growing global population, the demand for food and water will increase. Knowledge about ecosystems will provide opportunities for sustainable agriculture production in both terrestrial and marine environments. Diarrheal diseases and associated childhood deaths are strongly linked to poor water quality, sanitation, and hygiene. Even though improvements are being made, nearly 750 million people still lack access to reliable water sources. Ecosystems such as forests, wetlands, and lakes capture, filter, and store water used for drinking, irrigation, and other human purposes. Wetlands also store and treat solid waste and wastewater, and such ecosystem services could become of increasing use for sustainable development. Ecosystems contribute to local climate regulation and are of importance for climate change mitigation and adaptation. Coastal ecosystems, such as mangrove and coral reefs, act as natural barriers against storm surges and flooding. Flooding is associated with increased risk of deaths, epidemic outbreaks, and negative health impacts from destroyed infrastructure. Vegetation reduces the risk of flooding, also in cities, by increasing permeability and reducing surface runoff following precipitation events. The urban heat island effect will increase city-center temperatures during heatwaves. The elderly, people with chronic cardiovascular and respiratory diseases, and outdoor workers in cities where temperatures soar during heatwaves are in particular vulnerable to heat. Vegetation and especially trees help in different ways to reduce temperatures by shading and evapotranspiration. Air pollution increases the mortality and morbidity risks during heatwaves. Vegetation has been shown also to contribute to improved air quality by, depending on plant species, filtering out gases and airborne particulates. Greenery also has a noise-reducing effect, thereby decreasing noise-related illnesses and annoyances. Biological control uses the knowledge of ecosystems and biodiversity to help control human and animal diseases. Natural surroundings and urban parks and gardens have direct beneficial effects on people’s physical and mental health and well-being. Increased physical activities have well-known health benefits. Spending time in natural environments has also been linked to aesthetic benefits, life enrichments, social cohesion, and spiritual experience. Even living close to or with a view of nature has been shown to reduce stress and increase a sense of well-being.