In those cities with high air pollution levels and a combination of geography and weather that prevents pollutants from dispersing, ambient air pollution can pose a significant health risk to rich and poor alike. That risk is compounded in cities where air pollution regulations or enforcement is weak. Worldwide, an estimated 1.1 billion urban residents are exposed to particulate or sulfur dioxide levels in excess of the guidelines set by the World Health Organization (WHO)[1].

Although air pollution traditionally has been linked to industrial emissions, motor vehicles have now become a major source of pollution in many cities. The problem is particularly pronounced in cities with large numbers of poorly maintained vehicles and widespread use of leaded gasoline, which is still common in Latin America, Asia, and Eastern Europe.

Studies confirm the ill effects of outdoor air pollution on health. Pollution at the levels typically found in the air of large cities has been implicated in both acute and chronic illnesses, such as asthma and chronic bronchitis. Those most vulnerable are children, the elderly, cigarette smokers, and those who already have respiratory difficulties. Most research has concentrated on particulate matter, sulfur dioxide, and nitrogen oxides. The most dangerous pollutants appear to be small particles under 10 microns in diameter, which can be easily breathed into the lungs[2][3]. These arise mostly from motor vehicle exhaust, coal-fired power plants and boilers, and certain manufacturing industries.

Recent studies give strong evidence of the relationship between particulate air pollution and premature death[4][5]. One U.S. study that followed some 550,000 people in 151 cities over 7 years found that residents of the most polluted cities have a 15 to 17 percent higher risk of premature death from all causes than residents of the least polluted cities[6][7]. Since the late 1970s, epidemiological data from cities in the United States have consistently suggested that air pollution kills --primarily through respiratory or cardiovascular disease -- about 30,000 to 60,000 people per year, accou nting directly for 2 to 3 percent of all deaths[8][9].

Such results have been replicated in urban areas in other countries as well. Studies in the Czech Republic and in Poland, parts of which suffer from very high pollutant levels, suggest that, as in the United States, 2 to 3 percent of all deaths there could be attributed to air pollution[10][11]. A similar study in Jakarta, Indonesia, where concentrations of particulates are also very high, estimates that reducing airborne particulates to the level recommended by WHO could prevent 1,400 deaths, about 2 percent of annual deaths in the city[12][13].

Although these data suggest that air-pollution-related deaths are only a modest contributor to urban mortality rates, the role of air pollution in causing ill health among urbanites is much wider. For example, in Jakarta, researchers estimated that compliance with WHO guidelines could prevent some 600,000 asthma attacks and 125,000 cases of bronchitis in children each year[14].

References and notes

1. Dietrich Schwela, "Public Health Implications of Urban Air Pollution in Developing Countries," paper presented at the 10th World Clean Air Congress, Erjos, Finland, May 28-June 2, 1995, p. 1.

2. C. Arden Pope III et al., "Respiratory Health and PM-10 Pollution: A Daily Time Series Analysis," American Review of Respiratory Disease, Vol. 144, No. 3 (September 1, 1991), p. 668.

3. Douglas W. Dockery et al., "An Association Between Air Pollution and Mortality in Six U.S. Cities," New England Journal of Medicine, Vol. 329, No. 24 (December 9, 1993), p. 1753.

4. Ibid.

5. C. Arden Pope III et al., "Particulate Air Pollution as a Predictor of Mortality in a Prospective Study of U.S. Adults," American Journal of Respiratory and Critical Care Medicine, Vol. 151, No. 3 (March 1995), p. 669-674.

6. Ibid., p. 669.

7. Op. cit. 3, p. 1758.

8. Op. cit. 5, p. 672.

9. Philip J. Hilts, "Studies Say Soot Kills up to 60,000 in U.S. Each Year," New York Times (July 19, 1993), p. A1.

10. Marek Jakubowski, "Ambient Air Pollution and Health Effects," in Air Pollution in Central and Eastern Europe: Health and Public Policy (Management Sciences for Health, Boston, 1991).

11. Martin Bobak and Richard G.A. Feachem, "Air Pollution and Mortality in Central and Eastern Europe: An Estimate of the Impact," European Journal of Public Health, Vol. 5 (1995), pp. 82-86.

12. Bart Ostro, "Estimating the Health Effects of Air Pollutants: A Method with an Application to Jakarta," Policy Research Working Paper No. 1301 (The World Bank, Washington, D.C., 1994), p. 47.

13. Bart Ostro, Chief, Air Toxicology and Epidemiology Unit, California Environmental Protection Agency, Berkeley, California, 1995 (personal communication).

14. Op. cit. 12, p. 114.