Low-level ozone, particulate matter, and children with asthma.

Gent JF, Triche EW, Holford TR, Belanger K, Bracken MB, Beckett WS, Leaderer BP. 2003. Association of low-level ozone and fine panicles with respiratory symptoms in children with asthma. JAMA 290:1859-1867.

Many studies have shown that children with asthma are particularly vulnerable to adverse health effects from exposure to high levels of ambient ozone and particulate matter. These studies have shown that children with asthma living in areas that regularly experience periods

of high levels of these pollutants are at significant risk for respiratory symptoms, decreases in lung function, and the need for asthma medication such as rescue inhalers. But results from other epidemiologic studies of children with asthma living in regions with levels of pollution within or near compliance with Environmental Protection Agency (EPA) standards suggest that even these standards may not protect this more vulnerable group. The current study, conducted by NIEHS grantees Brian P. Leaderer of the Yale University School of Medicine and William S. Beckett of the University of Rochester School of Medicine and Dentistry in New York, examines the simultaneous effects of ozone and particulate matter at levels below EPA standards on daily respiratory symptoms and rescue medication use among children with asthma.

The researchers examined 271 children from a cohort of families living in New England who were participating in a study of asthma development. For each child, the team recorded demographic information, a medical history, daily respiratory symptoms (wheeze, persistent cough, chest tightness, and shortness of breath), and medication use (maintenance medications including inhaled and systemic steroids and leukotriene inhibitors, and rescue medications including bronchodilators). Air quality assessments over the 183-day sampling period were obtained from state departments of environmental protection.

For ozone, same-day concentrations above a 1-hour average of 63.3 parts per billion and an 8-hour average of 51.6 parts per billion were significantly associated with respiratory symptoms and rescue medication use among children with asthma severe enough to require using maintenance medication. These concentrations are significantly lower than the EPA standards of 120 and 80 parts per billion, respectively. Levels of particulate matter were not associated with any outcome in children with asthma, and no exposure-dependent associations were observed for any outcome with either pollutant among children who were not using maintenance medication.

The finding that asthmatic children are particularly vulnerable to ozone at levels below current EPA standards has major public health implications. On days when the ozone level is considered safe for the general population, this at-risk group may need to take additional precautions. Parents and physicians need to be aware of ozone alert forecasts and may need to take measures to limit outdoor activity for children with asthma on days when ozone is elevated but still below accepted standards.