Air pollution: brown skies research.

Direct information on the health effects of air pollution in humans relies mainly on chamber studies and epidemiological studies. Although chamber studies have limitations they allow the acute effects of individual pollutants to be studied in well characterised subjects under controlled conditions. Most chamber studies have shown relatively small falls in lung function and relatively small increases in bronchial reactivity at the concentrations of ozone, SO2, and NO2 that occur even during high pollution episodes in the UK. The possible exception is SO2 where sensitive asthmatic patients may show a greater response at concentrations that are seen from time to time in certain areas and in proximity to power stations. There is no convincing evidence of potentiation between pollutants in chamber studies. Epidemiological studies are more difficult to carry out and require considerable epidemiological and statistical expertise to deal with the main problem-confounding by other factors. Although the health effects seen with current levels of pollution are small compared with those seen in the 1950s and close to the limits of detection, this should not be interpreted as being unimportant. A small effect may have large consequences when the population exposed is large (the whole population in this case). Recent data suggest that particles have more important health effects than the pollutant gases that have been studied. Much of this information comes from the USA though the findings are probably applicable in the UK. More information is needed on the size of the health effects that occur during the three types of air pollution episodes seen in this country and the relative contributions of particles, pollutant gases, pollen, and other factors such as temperature. Research into air pollution declined in the UK following the introduction of the Clean Air Acts; it is now increasing again following pressure from certain individuals and ginger groups, including the British Lung Foundation, and its potential importance is recognised by the Department of Health. This article has concentrated on the acute effects of air pollution episodes, though the long term effects of acute episodes of air pollution and chronic high levels of pollutants is equally, if not more, important. Roger Altounyan had severe chest-disease attributed to asthma and personal pollution (cigarette smoke). But did the smog episodes in Manchester in the 1950s or subsequent vehicle related pollution play a part and did they interact with the bronchial challenges he underwent over the years (estimated at 3000)? Air pollution is a product of the way that society chooses to live. Obtaining an accurate picture of the extent to which current levels of air pollution cause acute and chronic effects on health is important if sensible choices are to be made by individuals and society about the processes contributing to air pollution. It is also important for patients with or at risk of developing cardiorespiratory disease.