The World Health Organization reports that 3 million people now die each year from the effects of air pollution. This is three times the 1 million who die each year in automobile accidents. A study published in The Lancet in 2000 concluded that air pollution in France, Austria, and Switzerland is responsible for more than 40,000 deaths annually in those three countries. About half of these deaths can be traced to air pollution from vehicle emissions.

In the United States, traffic fatalities total just over 40,000 per year, while air pollution claims 70,000 lives annually. U.S. air pollution deaths are equal to deaths from breast cancer and prostate cancer combined. This scourge of cities in industrial and developing countries alike threatens the health of billions of people.

Governments go to great lengths to reduce traffic accidents by fining those who drive at dangerous speeds, arresting those who drive under the influence of alcohol, and even sometimes revoking drivers' licenses. But they pay much less attention to the deaths people cause by simply driving the cars. While deaths from heart disease and respiratory illness from breathing polluted air may lack the drama of deaths from an automobile crash, with flashing lights and sirens, they are no less real.

Air pollutants include carbon monoxide, ozone, sulfur dioxide, nitrogen oxides, and particulates. These pollutants come primarily from the combustion of fossil fuels, principally coal-fired power plants and gasoline-powered automobiles. Nitrogen oxides can lead to the formation of ground-level ozone. Particulates are emitted from a variety of sources, primarily diesel engines. "Smog"-a hybrid word used to describe the mixture of smoke and fog that blankets some cities-is primarily composed of ozone and particulates.

The air in most urban areas typically contains a mixture of pollutants, each of which may increase a person's vulnerability to the effects of the others. Exposure to carbon monoxide slows reflexes and causes drowsiness, since carbon monoxide molecules bind to hemoglobin, reducing the amount of oxygen that red blood cells can carry. Nitrogen dioxide can aggravate asthma and reduce lung function, as well as making airways more sensitive to allergens. Ozone also causes lung inflammation and reduces lung function and exercise capacity.

Smaller particulates, especially those 10 micrometers in diameter (1/2,400 of an inch) or smaller, can become lodged in the alveolar sacs of the lungs. They are associated with higher admissions to hospital for respiratory problems and with increased mortality, particularly from respiratory and cardiovascular diseases. As particulate concentrations in the air rise, so do death rates.

When people inhale particulates and ozone at concentrations commonly found in urban areas, their arteries become more constricted, thus reducing blood flow and oxygen supply to the heart. This is why air pollution aggravates heart conditions and asthma.

Unlike some pollutants that have threshold levels below which no health effects are seen, ozone and particulates have negative health effects even at very low levels. Thus no "safe" level of such pollutants exists. Research published in Science in 2001 noted that in industrial as well as developing countries, exposures to current levels of ozone and particulates "affect death rates, hospitalizations and medical visits, complications of asthma and bronchitis, days of work lost, restricted-activity days, and a variety of measures of lung damage."

While these affect health care systems, they also take a toll on the economy. The increased monetary expenses related to air pollution induced illness include the costs of medication, absences from work, and child care expenses. In the Canadian province of Ontario, for example, which has a population of 11.9 million, air pollution costs citizens at least $1 billion annually in hospital admissions, emergency room visits, and worker absenteeism. According to the World Bank, the social costs of exposure to airborne dust and lead in Jakarta, Bangkok, and Manila approached 10 percent of average incomes in the early 1990s. In China, which has some of the world's worst urban air pollution, the illnesses and deaths of urban residents due to air pollution are estimated to cost 5 percent of the gross domestic product.

The economic costs of air pollution argue for reducing income taxes and raising taxes on fossil fuels. This would encourage more efficient fuel use, a shift to clean energy sources, and the adoption of pollution controls. The alternative is to spend more on health insurance to treat air pollution-related ailments. Raising the costs of polluting fuels will reduce suffering and premature death.

In response to traffic congestion and their notorious air pollution problems, Mexico City and São Paulo restrict people from driving on certain days of the week, based on the last digit on their license plates. And Bogotá, Colombia, has put in place a series of measures to reduce air pollution from transportation; in the process, it has become a more livable city. Since 1995, the city has reduced traffic during rush hours by 40 percent and increased the gasoline tax. Some 120 kilometers (75 miles) of main arteries are closed for seven hours each Sunday, which allows the streets to be used for walking, bicycling, and jogging.

The solutions to urban air pollution are not difficult to discern. Individuals can reduce car usage in favor of cycling, walking, and mass transit and can use more fuel-efficient cars. Urban planning commissions and regional governments can redirect transportation funding toward mass transit options: light rail, heavy rail, or rapid bus transit.

Zoning laws and other regulatory tools can be used to encourage the higher density development that is conducive to mass transit. And countries can shift electricity generation from coal and natural gas toward wind and solar power, using the lever of government subsidies and tax incentives for clean energy, rather than continuing to subsidize fossil fuels.

When purchasing a new car, consumers typically consider price, extra features, safety, and sometimes fuel economy. The fact that air pollution fatalities substantially exceed traffic fatalities worldwide suggests the need to broadly redefine notions of safety to include the goal of decreasing air pollution. While only some motorists contribute to traffic fatalities, all motorists contribute to air pollution fatalities.

Copyright © 2002 Earth Policy Institute