Journalists and the public have become increasingly concerned about the possible effects of the weather and air pollution on health. This anxiety has been exacerbated in Britain by the recent hot weather, the advent of warnings about air quality, and the availability of measurements of air quality on Ceefax. What sensible advice can be given to people about their response to episodes of air pollution?

The first challenge is to identify just who is at risk during these episodes. Most of the relevant research has come from two types of study. Panel studies take a group of people and follow up symptoms and lung function for a period during which air quality is thought likely to become poor. Event studies report effects of unusual episodes of pollution on a group of patients already recording symptoms or peak flow, or both, daily. Most of the studies conducted in North America have been of children attending summer camps, where the exposures were to ozone, acid aerosols, and particulates - …