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Review Air pollution and health

These efforts have attenuated the emissions engendered by growth, but 24-hour PM10 (particulate matter with aerodynamic diameter less than 10 m) concentrations exceeding several hundred µg/m3 are still measured at many monitoring sites. 1,2 A persistent haze blankets the city, especially during winter, and there is great concern among residents and visitors about the effects of suspended particles on health. Aerosols that contribute to this visibility degradation are usually a combination of primary and secondary particles. Primary particles are directly emitted from different sources, while secondary particles form in the atmosphere from gaseous emissions of sulfur dioxide, oxides of nitrogen, ammonia, and heavy organic gases. Secondary aerosol formation may. | REVIEW Review Air pollution and health Bert Brunekreef Stephen T Holgate The health effects of air pollution have been subject to intense study in recent years. Exposure to pollutants such as airborne particulate matter and ozone has been associated with increases in mortality and hospital admissions due to respiratory and cardiovascular disease. These effects have been found in short-term studies which relate day-to-day variations in air pollution and health and long-term studies which have followed cohorts of exposed individuals over time. Effects have been seen at very low levels of exposure and it is unclear whether a threshold concentration exists for particulate matter and ozone below which no effects on health are likely. In this review we discuss the evidence for adverse effects on health of selected air pollutants. December 2002 marks the 50th anniversary of the great smog event in London UK. Stagnant weather conditions caused a sharp increase in the concentration of air pollutants and over several days more than three times as many people died than expected leading to an estimated excess death toll of over 4000. Concentrations of sulphur dioxide and smoke reached several thousands of g per m3.1 The London 1952 smog was not without precedent similar events occurred in the Meuse valley Belgium in 1930 and elsewhere.2 3 Conditions have changed effective legislation has eliminated most of the air pollution of 50 years ago. Yet the 1952 London smog event keeps attracting the attention of contemporary air pollution scientists. One question that remains important is the extent to which air pollution affects life expectancy. The 1954 report1 suggests that death occurred mostly in individuals who were on the brink of death already but if this were the case the death rate should have dropped sharply after the episode. On the contrary the death rate remained high for several months and a recent re-analysis of the data indicates that the number of additional deaths .