Managing water in cities presents a series of intersecting challenges. Rapid urbanization, wasteful consumption, minimal efforts at urban or ecological planning, and especially climate change have made management of urban water more difficult. Urban water management is multifaceted and interconnected: cities must at once address problems of too much water (i.e., more frequent and extreme weather events, increased riverine and coastal flooding, and rising sea levels), but also not enough water (e.g., drought and water scarcity), as well as the need to protect the quality of water and water bodies.
This article presents a comprehensive and holistic picture of water planning challenges facing cities, and the historical approaches and newer methods embraced by cities with special attention to the need to consider the special effects of climate change on these multiple aspects of water and the role of ecological planning and design in responding to them. Ecological planning represents the best and most effective approach to urban water management, and ecological planning approaches hold the most promise for achieving the best overall outcomes in cities when taking into account multiple benefits (e.g., minimizing natural hazards, securing a sustainable water supply) as well as the need to protect and restore the natural environment. There are many opportunities to build on to the history of ecological planning, and ecological planning for water is growing in importance and momentum. Ecological planning for water provides the chance to profoundly rethink and readjust mankind’s relationship to water and provides the chance also to reimagine and reshape cities of the 21st century.
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Ecological Water Management in Cities
Timothy Beatley
Article
Radiation and the Environment
E. Jerry Jessee
The “Atomic Age” has long been recognized as a signal moment in modern history. In popular memory, images of mushroom clouds from atmospheric nuclear weapons tests recall a period when militaries and highly secretive atomic energy agencies poisoned the global environment and threatened human health. Historical scholarship has painted a more complicated picture of this era by showing how nuclear technologies and radioactive releases transformed the environment sciences and helped set the stage for the scientific construction of the very idea of the “global environment.”
Radioactivity presented scientists with a double-edged sword almost as soon as scientists explained how certain unstable chemical elements emit energic particles and rays in the process of radioactive decay at the turn of the 20th century. Throughout the 1920s and 1930s, scientists hailed radioactivity as a transformative discovery that promised to transform atomic theory and biomedicine by using radioisotopes—radioactive versions of stable chemical elements—which were used to tag and trace physiological processes in living systems. At the same time, the perils of overexposure to radioactivity were becoming more apparent as researchers and industrial workers laboring in new radium-laced luminescent paint industries began suffering from radiation-induced illnesses.
The advent of a second “Atomic Age” in wake of the bombing of Japan was characterized by increased access to radiotracer technologies for science and widespread anxiety about the health effects of radioactive fallout in the environment. Powerful new atomic agencies and military institutions created new research opportunities for scientists to study the atmospheric, oceanic, and ecological pathways through which bomb test radiation could make their way to human bodies. Although these studies were driven by concerns about health effects, the presence of energy-emitting radioactivity in the environment also meant that researchers could utilize it as a tracer to visualize basic environmental processes. Throughout the 1950s and early 1960s, as a result, ecologists pioneered the use of radiotracers to investigate energy flows and the metabolism of ecosystem units. Oceanographers similarly used bomb blast radiation to trace the physical processes in oceans and the uptake of radioactivity in aquatic food chains. Meteorologists meanwhile tracked bomb debris as high as the stratosphere to predict fallout patterns and trace large-scale atmospheric phenomenon. By the early 1960s, these studies documented how radioactive fallout produced by distant nuclear tests spread across the globe and infiltrated the entire planet’s air, water, biosphere, and human bodies.
In 1963, the major nuclear powers agreed to end above-ground nuclear testing with the Limited Test Ban Treaty, the first international treaty to recognize a global environmental hazard of planetary proportions. Throughout the 1960s and into the 1980s, research on the global effects of nuclear weapons continued to shape global environmental thinking and concern as debates about nuclear winter directed professional and public attention toward humanity’s ability to alter the climate.
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Environmental Degradation, Tropical Diseases, and Economic Development
John Luke Gallup
It’s complicated. Tropical diseases have unusually intricate life cycles because most of them involve not only a human host and a pathogen, but also a vector host. The diseases are predominantly tropical due to their sensitivity to local ecology, usually due to the vector organism. The differences between the tropical diseases mean that they respond to environmental degradation in various ways that depend on local conditions. Urbanization and water pollution tend to limit malaria, but deforestation and dams can exacerbate malaria and schistosomiasis. Global climate change, the largest environmental change, will likely extend the range of tropical climate conditions to higher elevations and near the limits of the tropics, spreading some diseases, but will make other areas too dry or hot for the vectors. Nonetheless, the geographical range of tropical diseases will be primarily determined by public health efforts more than climate. Early predictions that malaria will spread widely because of climate change were flawed, and control efforts will probably cause it to diminish further. The impact of human disease on economic development is hard to pin down with confidence. It may be substantial, or it may be misattributed to other influences. A mechanism by which tropical disease may have large development consequences is its deleterious effects on the cognitive development of infants, which makes them less productive throughout their lives.
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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.
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Urban Heat Islands and Their Associated Impacts on Health
Clare Heaviside
Towns and cities generally exhibit higher temperatures than rural areas for a number of reasons, including the effect that urban materials have on the natural balance of incoming and outgoing energy at the surface level, the shape and geometry of buildings, and the impact of anthropogenic heating. This localized heating means that towns and cities are often described as urban heat islands (UHIs). Urbanized areas modify local temperatures, but also other meteorological variables such as wind speed and direction and rainfall patterns. The magnitude of the UHI for a given town or city tends to scale with the size of population, although smaller towns of just thousands of inhabitants can have an appreciable UHI effect. The UHI “intensity” (the difference in temperature between a city center and a rural reference point outside the city) is on the order of a few degrees Celsius on average, but can peak at as much as 10°C in larger cities, given the right conditions. UHIs tend to be enhanced during heatwaves, when there is lots of sunshine and a lack of wind to provide ventilation and disperse the warm air. The UHI is most pronounced at night, when rural areas tend to be cooler than cities and urban materials radiate the energy they have stored during the day into the local atmosphere.
As well as affecting local weather patterns and interacting with local air pollution, the UHI can directly affect health through heat exposure, which can exacerbate minor illnesses, affect occupational performance, or increase the risk of hospitalization and even death. Urban populations can face serious risks to health during heatwaves whereby the heat associated with the UHI contributes additional warming. Heat-related health risks are likely to increase in future against a background of climate change and increasing urbanization throughout much of the world. However, there are ways to reduce urban temperatures and avoid some of the health impacts of the UHI through behavioral changes, modification of buildings, or by urban scale interventions. It is important to understand the physical properties of the UHI and its impact on health to evaluate the potential for interventions to reduce heat-related impacts.
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Environmental Health Research: Identifying the Context and the Needs, and Choosing Priorities
George Morris, Marco Martuzzi, Lora Fleming, Francesca Racioppi, and Srdan Matic
Adequate funding, careful planning, and good governance are central to delivering quality research in any field. Yet, the strategic directions for research, the mechanisms through which topics emerge, and the priorities assigned are equally deserving of attention. The need to understand the role played by the environment and to manage the physical environment and the human activities which bear upon it in pursuit of health, well-being, and equity are long established. These imperatives drive environmental health research as a key branch of scientific inquiry.
Targeted research over many years, applying established methods, has informed society’s understanding of the toxic, infectious, allergenic, and physical threats to health from our physical surroundings and how these may be managed. Essentially hazard-focused research continues to deliver policy-relevant findings while simultaneously posing questions to be addressed through further research. Environmental health in the 21st century is, however, confronted by additional challenges of a rather different character. These include the need to understand, in a better and more policy-relevant way, the contributions of the environment to health and equity in complex interaction with other societal and individual-level influences (a so-called socioecological model). Also important are the potential of especially green and blue natural environments to improve health and well-being and promote equity, and the health implications of new approaches to production and consumption, such as the circular economy.
Such challenges add breadth, depth, and richness to the environmental health research agenda, but when combined with the existential and public health threat of humanity’s detrimental impact on the Earth’s systems, they entail a need for new and better strategies for scientific inquiry. As we confront the challenges and uncertainties of the Anthropocene, the complexity expands, the stakes become sky-high, and diverse interests and values clash. Thus, the pressure on environmental health researchers to evolve and engage with stakeholders and reach out to the widest constituency of policy and practice has never been greater, nor has the need to organize to deliver.
A disparate range of contextual factors have become pertinent when scoping the now significantly extended, territory for environmental health research. Moreover, the challenges of prioritizing among the candidate topics for investigation have scarcely been greater.
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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.
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Environmental Health Impacts of Natural and Man-Made Chemicals
Michael N. Moore
Humans have been exposed to naturally occurring toxic chemicals and materials over the course of their existence as a species. These materials include various metals, the metalloid arsenic, and atmospheric combustion particulates, as well as bacterial, fungal, algal, and plant toxins. They have also consumed plants that contain a host of phytochemicals, many of which are believed to be beneficial, such as plant polyphenols. People are exposed to these various substances from a number of sources. The pathways of exposure include air, water, groundwater, soil (including via plants grown in toxic soils), and various foods, such as vegetables, fruit, fungi, seafood and fish, eggs, wild birds, marine mammals, and farmed animals.
An overview of the various health benefits, hazards and risks relating to the risks reveals the very wide variety of chemicals and materials that are present in the natural environment and can interact with human biology, to both its betterment and detriment.
The major naturally occurring toxic materials that impact human health include metals, metalloids (e.g., arsenic), and airborne particulates. The Industrial Revolution is a major event that increased ecosystem degradation and the various types and duration of exposure to toxic materials. The explosions in new organic and organometallic products that were and still are produced over the past two centuries have introduced new toxicities and associated pathologies. The prevalence in the environment of harmful particulates from motor-vehicle exhaust emissions, road dust and tire dust, and other combustion processes must also be considered in the broader context of air pollution.
Natural products, such as bacterial, fungal, algal, and plant toxins, can also have adverse effects on health. At the same time, plant-derived phytochemicals (i.e., polyphenols, terpenoids, urolithins, and phenolic acids, etc.) also have beneficial and potential beneficial effects, particularly with regard to their anti-inflammatory effects. Because inflammation is associated with most disease processes, phytochemicals that have antioxidant and anti-inflammatory properties are of great interest as potential nutraceuticals. These potentially beneficial compounds may help to combat various cancers; autoimmune conditions; neurodegenerative diseases, including dementias; and psychotic conditions, such as depression, and are also essential micronutrients that promote health and well-being. The cellular and molecular mechanisms in humans that phytochemicals modulate, or otherwise interact with, to improve human health are now known.
In the early 21st century, some of the current pollution issues are legacy problems from past industrialization, such as mercury and persistent organic pollutants (POPs). These POPs include many organochlorine compounds (e.g., polychlorinated biphenyls, pesticides, polychlorinated and polybrominated dibenzo-dioxans and -furans), as well as polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, and others. The toxicity of chemical mixtures is still a largely unknown problem, particularly with regard to possible synergies. The continuing development of new organic chemicals and nanomaterials is an important environmental health issue; and the need for vigilance with respect to their possible health hazards is urgent. Nanomaterials, in particular, pose potential novel problems in the context of their chemical properties; humans have not previously been exposed to these types of materials, which may well be able to exploit gaps in our existing cellular protection mechanisms.
Hopefully, future advances in knowledge emerging from combinatorial chemistry, molecular modeling, and predictive quantitative structure-activity relationships (QSARs), will enable improved identification of the potential toxic properties of novel industrial organic chemicals, pharmaceuticals, and nanomaterials before they are released into the natural environment, and thus prevent a repetition of past disastrous events.
Article
Pollen, Allergens, and Human Health
Rachel N. McInnes
Allergenic pollen is produced by the flowers of a number of trees, grasses, and weeds found throughout the world. Human exposure to such pollen grains can exacerbate pollen-related asthma and allergenic conditions such as allergic rhinitis (hay fever). While allergenic pollen comes from three main groups of plants—certain trees, grasses, and weeds—many people are sensitive to pollen from one or a few taxa only. Weather, climate, and environmental conditions have a significant impact on the levels and varieties of pollen grains present in the air. These allergenic conditions significantly reduce the quality of life of affected individuals and have been shown to have a major economic impact.
Pollen production depends on both the current meteorological conditions (including day length, temperature, irradiation, precipitation, and wind speed/direction), and the water availability and other environmental and meteorological conditions experienced in the previous year. The climate affects the types of vegetation and taxa that can grow in a particular location through availability of different habitats. Land-use or land management is also crucial, and so this field of study has implications for vegetation management practices and policy.
Given the influential effects of weather and climate on pollen, and the significant health impacts globally, the total effect of any future environmental and climatic changes on aeroallergen production and spread will be significant. The overall impact of climate change on pollen production and spread remains highly uncertain, and there is a need for further understanding of pollen-related health impact information. There are a number of ways air quality interacts with the impact of pollen. Further understanding of the risks of co-exposure to both pollen and air pollutants is needed to better inform public health policy. Furthermore, thunderstorms have been linked to asthma epidemics, especially during the grass pollen seasons. It is thought that allergenic pollen plays a role in this “thunderstorm asthma.”
To reduce the exposure to, or impact from, pollen grains in the air, a number of adaptation and mitigation options may be adopted. Many of these would need to be done either through policy changes, or at a local or regional level, although some can be done by individuals to minimize their exposure to pollen they are sensitive to. Improved aeroallergen forecast models could be developed to provide detailed taxon-specific, localized information to the public. One challenge will be combining the many different sources of aeroallergen data that are likely to become available in future into numerical forecast systems. Examples of these potential inputs are automated observations of aeroallergens, real-time phenological observations and remote sensing of vegetation, social sensing, DNA analysis of specific aeroallergens, and data from symptom trackers or personal monitors. All of these have the potential to improve the forecasts and information available to the public.
Article
Valuing the Benefits of Green Stormwater Infrastructure
Amy W. Ando and Noelwah R. Netusil
Green stormwater infrastructure (GSI), a decentralized approach for managing stormwater that uses natural systems or engineered systems mimicking the natural environment, is being adopted by cities around the world to manage stormwater runoff. The primary benefits of such systems include reduced flooding and improved water quality. GSI projects, such as green roofs, urban tree planting, rain gardens and bioswales, rain barrels, and green streets may also generate cobenefits such as aesthetic improvement, reduced net CO2 emissions, reduced air pollution, and habitat improvement. GSI adoption has been fueled by the promise of environmental benefits along with evidence that GSI is a cost-effective stormwater management strategy, and methods have been developed by economists to quantify those benefits to support GSI planning and policy efforts. A body of multidisciplinary research has quantified significant net benefits from GSI, with particularly robust evidence regarding green roofs, urban trees, and green streets. While many GSI projects generate positive benefits through ecosystem service provision, those benefits can vary with details of the location and the type and scale of GSI installation. Previous work reveals several pitfalls in estimating the benefits of GSI that scientists should avoid, such as double counting values, counting transfer payments as benefits, and using values for benefits like avoided carbon emissions that are biased. Important gaps remain in current knowledge regarding the benefits of GSI, including benefit estimates for some types of GSI elements and outcomes, understanding how GSI benefits last over time, and the distribution of GSI benefits among different groups in urban areas.
