John Peters, MD, Sc.D.
Background: Asthma among children has been on the rise in the U.S. and other developed countries for the past 20-30 years and has become the most common chronic disease among children in this country. Approximately 9 million children in the U.S. suffer from asthma, which is one of the leading causes of school absenteeism and causes millions of lost work hours for parents who must stay home to look after sick children.
Poor air quality has been recognized for some time as a trigger for asthma attacks. Pollutants such as ozone, nitrogen dioxides, and particulate matter have been suggested as possible culprits for these attacks, but little has been known regarding their effects on causing asthma to develop in children.
Advance: Researchers at the University of Southern California have shown for the first time that ozone may actually cause asthma. In a study of 3500 children with no history of asthma from 12 southern California communities, 265 new diagnoses of asthma were reported during a 5-year period. Children who played three or more sports in areas with high ozone concentrations were over three times as likely to develop asthma as children who did not play any sports. Time spent outdoors was also associated with the development of asthma. There was no increased risk for asthma development in areas of low ozone concentration. Exposure to other air pollutants was not associated with increased risk of developing asthma.
Implication: These findings indicate that high exposure to ozone through time spent outdoors in contaminated air and increased breathing rates from physical activity might affect the development of asthma in previously health children. These findings could have policy implications as nations try to tackle the problem of balancing the economic costs of clean air with protecting the health of their citizens.
Citation: McConnell R, Berhane K, Gilliland F, London SJ, Islam T, Gauderman WJ, Avol E, Margolis HG, Peters JM. Asthma in exercising children exposed to ozone: a cohort study. Lancet. 2002 Feb 2;359(9304):386-91.