Chapter 6: Health Effects of Urban Pollution

More research on the effects of air pollutants on health is probably being done today than at any time in history. This is remarkable in view of the fact that, in many developed countries, concentrations of many air pollutants are now low in comparison with earlier periods. The position is much more alarming in the developing world: there pollutant concentrations are rising and effects on health are increasing. Present concerns about even low concentrations of air pollutants have been fuelled by developments in epidemiological techniques: time-series analysis has played a large part in demonstrating that even for common and non-carcinogenic air pollutants such as ozone and sulfur dioxide there may be no threshold of effect - at least, not at a population level. Findings from these studies are discussed in this chapter. Another remarkable advance has been the realisation that long-term exposure to the ambient aerosol increases the likelihood, at all adult ages, of death from cardiovascular disease. This effect may be due to an increased rate of development of atheromatous plaques in the coronary arteries with rupture of plaques leading to myocardial infarction. Time-series studies have revealed that even short-term exposure to particles increases the likelihood of cardiovascular “events” and abnormalities in the rhythm of the heart. It has been suggested that the ultrafine component of the ambient aerosol plays a large part in causing these effects. This has, in part, led to the current surge of interest in nano-toxicology. The suggestion remains unproven.