World Resources 1996-97
(A joint publication by The World Resource Institute, The United
 Nations Environment Programme, The United Nations Development
 Programme, and the World Bank)
 (Edited by Dr. Róbinson Rojas)

1. Cities and the Environment

URBAN ENVIRONMENTAL PROBLEMS

As centers of population and human activities, cities consume natural resources from both near and distant sources. They also generate waste that is disposed of both inside and outside the city. In the process, urban areas generate environmental problems over a range of spatial scales: the household and workplace, the neighborhood, the city, the wider region, and the globe (110).

Urban environmental problems also create a range of social impacts. They may impair human health, cause economic and other welfare losses, or damage the ecosystems on which both urban and rural areas depend. Most urban environmental problems entail all three of these impacts, either directly or indirectly. For example, urban air pollution has a direct impact on human health, increasing the incidence of respiratory disease. Its impact on the economy is mainly indirect, arising largely from productivity losses due to ill health (111).

Determinants of Urban Environmental Problems

Environmental problems vary from city to city and region to region and are influenced by such variables as a city's size and rate of growth, income, local geography, climate, and institutional capabilities. Especially where local governments are weak or underfinanced, rapid economic or population growth can exacerbate th ese problems. Environmental management tends to be more difficult in very large cities. For one, the financial resources needed to provide services to tens of millions of people are daunting. Compounding the d ifficulty is the fact that the largest cities often are made up of many local jurisdictions with overlapping respo nsibilities (112)(113).

Income

One of the most important determinants of a city's environmental problems is its income level. As the wealth of a city grows, many types of environmental degradation first increase and then eventually diminish. Other environmental problems increase with wealth. (See Figure 1.3.)

The income level at which a city undergoes these changes differs widely. Vastly different environmental conditions can be found in cities of comparable wealth. Policies, as well as demography and geography, can make an enormous difference.

In poor cities, and particularly their poor neighborhoods, the most threatening environmental problems are usually those close to home (114). The dangers of exposure to environmental risks are high, especially for women and children. Inadequate household water supplies are typically more crucial to people's well-being than polluted waterways. There is often more exposure to air pollution in smoky kitchens than outdoors. Waste accumulating, uncollected, in the neighborhood poses more serious problems than the waste at the city dumps. Human excreta is frequently the most critical pollutant, and unsanitary conditions in the home and neighborhood are generally more of a threat to health than industrial pollution.

These problems, so prevalent in cities in the developing world, stem from myriad causes, including the inability or unwillingness of local governments to provide for basic needs of citizens--which in turn stems from a lack of revenue-generating capacity. Another key factor is the poor's lack of access to suitable land for housing.

As income increases, urban households and cities as a whole consume far more resources, such as energy, water, and building materials-- and generate far more of certain types of wastes. Yet the rich devote part of their wealth to measures that protect them from environmental hazards. The problems close to home are the first to improve as wealth increases, generally because they are the most threatening and require cooperation on only a relatively small scale. However, while these improvements reduce personal exposure, they often simply shift the problem elsewhere. Waterborne sewage systems, for example, reduce personal exposure to fecal material. However, if sewage is discharged without treatment, it can lower the quality of a city's waterways and strain water supplies. Electricity is a clean fuel where it is used, but electric power plants can be an important source of ambient air pollution.

Thus, even as household and neighborhood environmental problems recede from prominence for a growing number of a city's population, citywide and regional problems, such as ambient air pollution, water pollution, and hazardous waste generation, may increase. These problems tend to be severe in rapidly industrializing cities of the developing world and in the transition economies of Central and Eastern Europe, where industrial activity often occurs without adequate concern for its environmental implications. (See Box 1.6.) Lack of investment in urban infrastructure, such as increased road networks and sewage treatment plants, and weak environmental protection laws with lax enforcement, exacerbate these problems.

In high-income cities, such as those in Europe and North America, many of the worst city-level problems have been addressed. For instance, many cities in the developed world have improved the quality of their ambient air and water over the past decades. A wealthy city can more easily afford the public finance and administration needed to regulate the more perceptible forms of pollution.

But while the ambient environment of high-income cities may actually be more benign in terms of the health impacts of pollution, these cities exert a far greater toll on the regional and global environment. The resources consumed and greenhouse gases emitted to support even the cleanest cities in developed countries are, on a per capita basis, far greater than those associated with the poorer cities of developing regions. Indeed, the largest per capita urban contributors to global environmental problems are the wealthy, living preponderantly in the urban areas of the developed world.

Not confronted with the direct impacts of their activities on the global environment, wealthy cities and countries tend to have fewer incentives to address them. In manufacturing, for example, relatively little progress has been made in introducing "clean" production in the broadest sense of the term or in shifting from the linear material flows that characterize most modern technologies to the closed cycles that many advocate (115). As with global warming, the costs are often seen as too uncertain or too distant to compel action now.

In its broad outlines, the transition summarized above suggests an association among a city's wealth, its environment, and the health of its citizens. Generally, the poor create environmental problems for themselves and their neighbors, while the wealthy create problems for a wider public.

Natural Features

The natural features of a city and its surroundings--its geography, topography, and climate--are also critical determinants of the nature of its environmental problems. Climate, for instance, determines which disease vectors can thrive. London has been spared from malaria not because of its wealth but because it is too cold for the mosquito vector to survive. Mexico City and Los Angeles are especially plagued by air pollution not only from the number of cars per capita--associated with income--but also because they are bounded by mountains that prevent dispersal of air pollutants. Cities in cold regions often confront air pollution problems stemming from energy use for domestic heating, especially where low-quality coal is used, as in northern China and Eastern Europe (116).

When natural features are combined with the level and type of economic activity, they can be used to predict which types of problems are likely to be severe in different types of cities (117). For example, air pollution problems tend to rise with temperature extremes. In cold areas, more fuel is used for heating; in warm, sunny areas, contributions to ozone formation increase owing to the release of hydrocarbons and nitrogen oxides, particularly from motor vehicle fuel. Air pollution also rises with income level because, as is described above, levels of car use, industrial production, and fuel consumption are higher in wealthier cities.

The Brown Agenda

Although most of the world's population will soon be living in developing world cities, the environmental problems most prominent in these cities have often been conspicuously absent from the global environmental agenda. Indeed, over the past two decades the global agenda has shifted away from local and regional problems such as air pollution and inadequate water supplies toward vast global concerns such as ozone depletion, climate change, and the loss of biological diversity (118).

Aware of this disconnect between the "green" agenda and the problems confronting cities, a number of researchers, international donor agencies, and nongovernmental organizations over the past few years have advocated a renewed focus on the "brown" agenda--that is, the problems of pollution, poverty, and environmental hazards in cities (119) (120) (121). As one scholar noted, "The adverse effects of household airborne and water-carried wastes on child mortality and female life expectancy are of no less global proportion than, say, the destruction of tropical forests, and in immediate human terms, they may be the most urgent of all worldwide environmental problems" (122). This is not to argue for less attention to global concerns, but for the recognition that urban and global concerns are intertwined and must both be addressed. This section focuses on the "brown" problems so prominent in many of the world's cities.

Water and Sanitation

One of the greatest threats to human health in the developing world is the lack of adequate water and sanitation services. The International Drinking Water Supply and Sanitation Decade brought significant progress--the number of urban residents with access to an adequate water supply increased by approximately 80 percent--but those gains were overshadowed by rapid population growth. In 1994, at least 220 million people still lacked a source of potable water near their homes (123). (See Table 1.4.)

These statistics probably underestimate the actual number of people inadequately served. Definitions of what constitutes an adequate amount of safe drinking water and sanitation vary from country to country. Although many governments classify the existence of a water tap within 100 meters of a house as "adequate," such a tap does not guarantee that the individual household will be able to secure enough water for good health. Communities of 500 inhabitants or more are often served by one tap (124). Communal taps often function only a few hours each day, so residents must wait in long lines to fill even one bucket. For example, in Lucknow, India, a city with almost 2 million people, water is available only 10 hours each day (125). In smaller cities, the situation can be much worse. In Rajkot, India, for example, a city with a population of 600,000, the piped water runs for only 20 minutes each day (126). Households cannot obtain sufficient water for washing, laundry, and personal hygiene if it takes too long to fetch and if the water has to be carried long distances.

Statistics on national coverage also hide inequalities within a city. Although 80 percent of high-income urban residents in the developing world have a house-connected water supply, only 18 percent of low-income residents do (127). In many cities in developing countries, per capita water availability in marginal settlements can be anywhere from 3 to 10 times less than in better- off neighborhoods (128) (129) (130). Those without access to a safe water supply must buy water from vendors at costs of anywhere from 4 to 100 times higher than the cost of water from a piped city supply (131). In Lima, Peru, a poor family pays more than 20 times what a middle-class family pays for water (132).

The proportion of the urban population covered by sanitation services is even smaller. More than 420 million urban residents do not have access to even the simplest latrine (133). Many resort instead to open defecation on land or in waterways. As with the statistics on adequate water, estimates of the number unserved are probably low because they do not reflect the actual functioning or use of the facilities.

These figures also hide considerable inequalities among the rich and poor. In developing countries, 8 percent of urban low-income dwellers have a house sewer connection, compared with 62 percent of urban high-income dwellers (134). Low-income families often share latrines with 100 or more other community members, and long lines or overflowing tanks deter residents from using them at all.

Poor sanitation poses health hazards through several routes-- including direct exposure to feces near homes, contaminated drinking water, ingestion of fish from polluted waters, and ingestion of produce that has been fertilized by wastewater. Inadequate access to water and sanitation facilities is the main cause for the intestinal diseases, transmitted by feces, that are so prevalent in developing countries. Two of these diseases, diarrhea and intestinal worm infections, account for an estimated 10 percent of the total burden of disease in developing countries (135).

An estimated 2 million fewer children would die from diarrheal diseases each year if all people had access to adequate water and sanitation facilities, according to the World Bank (136). Diarrheal diseases alone killed more than 3 million children in 1993 and cause some 1.8 billion episodes of illness annually (137).

Wastewater Disposal

In the developing world, it is estimated that more than 90 percent of sewage is discharged directly into rivers, lakes, and coastal waters without treatment of any kind (138). Of  India's 3,119 towns and cities, only 8 have full wastewater collection and treatment facilities; 209 have partial treatment facilities (139). Even in higher-income countries such as Chile, where sanitation services are relatively well developed, domestic wastewater is still the main threat to water quality. Santiago has only one small pilot wastewater treatment plant, which processes a mere 4 percent of the city's wastewater; the rest is dumped into the rivers that run through the city (140).

Disposal of domestic wastewater remains a problem, although by no means as severe, in wealthier regions as well. In member countries of the Organisation for Economic Co-Operation and Development (OECD), approximately one third of the population is still not served by wastewater treatment plants (141). Many older U.S. cities have outmoded sewer systems that collect wastewater and storm water together, so that when rainfall is heavy, untreated wastewater is released through overflow drains (142).

Indoor Air Pollution

Indoor air pollution from burning of low-quality fuels, such as charcoal or animal dung, has been largely considered a rural problem. Yet many urban residents of the developing world rely on biomass fuels for cooking and heating. In many smaller urban centers in Asia and Africa, between 50 and 90 percent of domestic energy supplies come from these materials (143). Exposure tends to be highest for women and young children, who often spend many hours indoors and cooking over open fires; indeed, they face greater exposure to pollutants from indoor than outdoor air (144).

Data are scarce on the number of people affected by indoor air pollution, especially urban residents, but in 1992 the World Bank identified indoor air pollution as one of the four most critical global environmental problems (145). Indoor air pollution contributes to acute respiratory infections in young children and chronic lung diseases and cancer in adults (146). Acute respiratory infections, principally pneumonia, are the chief killers of young children in developing countries, accounting for an estimated 10 percent of the total burden of disease. Smoke contributes to acute respiratory infections that cause an estimated 4 million deaths annually among infants and children (147) (148).

Urban Air Pollution

Worldwide, more than 1.1 billion people live in urban areas with unhealthful air (149), exposed to a cocktail of pollutants released from industrial, energy, and vehicular sources. Air pollution is particularly severe in megacities such as Beijing, Seoul, Mexico City, and Cairo, Egypt, each of which exceeds WHO guidelines for at least two of the pollutants that WHO monitors (150). In Mexico City, suspended particulate matter from vehicles and others sources contributes to 6,400 deaths each year, and 29 percent of all children have unhealthy blood lead levels (151). The World Bank estimates that if particulate levels alone were reduced to WHO guidelines, between 300,000 and 700,000 premature deaths per year could be avoided globally (152). That is the equivalent of roughly 2 to 5 percent of all deaths in urban areas that have excessive levels of particulates. In addition, chronic coughing in urban children under age 14 could be reduced by half, or about 50 million cases annually, reducing the chance that these children will face permanent respiratory damage (153). Improving urban air quality should also reduce the incidence of chronic and infectious respiratory diseases.

Urban air quality in the more developed countries has generally improved over the past two decades, largely from advances in controlling emissions from stationary sources such as power plants. Rising motor vehicle use, in part reflecting the increasingly sprawling form of many cities, now poses the greatest threat to air quality (154) (155) (156). By contrast, urban air quality has generally deteriorated throughout the developing world and the formerly socialist economies. The reasons are increasing power generation, rising industrial activity, and rising motor vehicle use--especially of poorly maintained vehicles that use leaded fuel (157).

Air quality seems likely to worsen with rapid urban growth unless rigorous pollution control measures are put into effect. In many cities in developing countries, motor vehicle use per capita is relatively low, so cars are still a minor contributor to air pollution. Car ownership, however, is sparked by both increasing incomes and urbanization and is expected to skyrocket. In 1990, the global vehicle fleet (excluding two- and three-wheel vehicles)totaled some 580 million, but this will grow to an estimated 816 million vehicles by 2010 (158). Most of this growth will occur in the developing countries and in Central and Eastern Europe.

Lead is particularly hazardous to human health, and cars that still rely on leaded gasoline account for up to 95 percent of airborne lead pollution in cities in developing countries (159). The World Bank projects that under an "unchanged practices" scenario, lead emissions could increase fivefold from 1990 to 2030 (160). Even with efficiency reforms and pollution abatement measures, lead emissions would not disappear until after 2010 (161).

For many cities in developing countries, such as Cairo and Bangkok, ambient lead levels of 1.5 micrograms per cubic meter are common (162) (163) (164). In contrast, lead levels typically range from 0.2 to 0.8 micrograms per cubic meter in most North American and European cities (165). Along roads with high traffic density, lead levels tend to be especially high (166). Residents of the numerous informal settlements that are located next to major roads are thus subject to high levels of exposure.

Urban air pollution not only impairs human health but also damages crops, vegetation, and man-made structures, including historic monuments. These effects are more difficult to quantify. However, acid rain and transported air pollutants from automobiles and heavy industry have contributed to the decline of forest tracts downwind of urban areas (167) (168). As is noted above, cities are also among the major contributors to regional and global atmospheric pollution. (See Chapter 3, "Urban Impacts on Natural Resources." )

Solid and Hazardous Wastes

Cities generate tremendous amounts of solid waste, and those amounts increase with income. In cities of the developing world, an estimated 20 to 50 percent of the solid waste generated remains uncollected, even though up to one half of local operational expenditures often goes toward waste collection (169) (170). In Guatemala City, for instance, just 65 percent of municipal waste is collected; the rest is disposed of in unofficial locations in the metropolitan region (171). In low-income or squatter settlements, garbage collection is often nonexistent, either because these settlements fall outside "official" service areas or because trucks are unable to maneuver along narrow, unpaved streets. Uncollected domestic waste is the most common cause of blocked urban drainage channels in Asian cities, increasing the risk of flooding and vectorborne diseases (172). In some cities, refuse is often mixed with human excrement, which facilitates the spread of disease, especially among children and wastepickers.

In most OECD countries, 100 percent of the urban population is serviced by municipal waste collection (173). However, with their higher consumption levels, they confront ever-increasing mounds of garbage. Since 1980, the generation of municipal waste per capita has increased in all OECD countries except Germany (174) (175). Despite massive recycling and incineration proj-ects, Tokyo is unable to cope with the more than 22,000 metric tons of garbage generated each day; as a result, officials are building islands of waste in Tokyo Bay, which threaten both the shipping and the fishing industry (176).

Even if collected, municipal wastes remain a problem in many cities in developing countries. Municipal solid waste sites often handle both domestic and industrial wastes, including hazardous wastes. Without proper disposal, toxic chemicals can leach into water supplies. Few data exist on the composition of hazardous waste streams in developing countries. The OECD has compiled rough estimates of the volumes of industrial and hazardous wastes generated worldwide, yet no such data exist on their disposal (177). Effluents from chemical production, pulp and paper factories, mining industries, and leather and tanning processes are playing an increasing role in environmental pollution. If current trends are any indication, the volume of toxic heavy metals generated in countries such as China, India, the Republic of Korea, and Turkey could reach levels comparable to those of France and the United Kingdom within 15 years (178).

The lack of emissions standards or enforcement of regulations in many developing nations compounds pollution problems. Illegal dumping and improper disposal of toxic and hazardous wastes are common. In addition, industrial activity in the developing world tends to be concentrated in relatively few locations, often close to city centers (179). Three quarters of all Thai factories dealing with hazardous chemicals are located within Bangkok's metropolitan area and the neighboring provinces. This includes five of Thailand's seven lead smelting plants and more than 90 percent of its chemical, dry-cell battery, paint, pharmaceutical, and textile manufacturing plants (180). The concentration of people close to these industries increases the risks of exposure.

Exposures can be severe in the case of industrial accidents or dumping. Even so, they tend to be localized, in contrast to the citywide problems of air and water pollution (181). The health effects of hazardous wastes remain controversial, yet are generally believed to pose a far smaller threat than those associated with biological pathogens in the urban environment (182). In the developed world, where the most egregious exposures to hazardous wastes have largely been remedied, concern is mounting about exposures to even minute levels of toxic wastes (183) (184).

References and Notes


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