Both ozone and primary pollutants from traffic substantially increase asthma-related emergency department visits in children, especially during the warm season, according to research  from the Department of Environmental Health at the Rollins School of Public Health at Emory University in Atlanta..

Asthma exacerbations are known to be triggered by air pollutants, but researchers are still trying to determine what specific pollutants are to blame, and how much they increase pediatric emergency department visits for asthma.

"Characterizing the associations between ambient air pollutants and pediatric asthma exacerbations, particularly with respect to the chemical composition of particulate matter, can help us better understand the impact of these different components and can help to inform public health policy decisions," said lead author Matthew J. Strickland, PhD, MPH, assistant professor of environmental health.

The researchers  looked at data from metropolitan Atlanta emergency department visits for asthma exacerbations in children ages  5 to 17 between 1993 and 2004 and used data on ambient pollutant collected as part of the Study of Particles and Health in Atlanta (SOPHIA). They then analyzed the more than 90,000 asthma-related pediatric emergency department visits with respect to the ambient levels of 11 different pollutants. The availability of daily monitoring data on particulate matter components allowed them to establish a relationship between pollutant concentrations and subsequent effects on emergency department visits for pediatric asthma exacerbations.

Ozone was strongly associated with an increase in pediatric asthma exacerbations during the summer, and there was evidence of a dose-response relationship beginning with concentrations as low as 30 parts per billion, below the EPA 8-hour ozone standard of 75 ppb.

The researchers offered several possible explanations for why the pollution effects appeared stronger in the warm season, among them that children are more likely to play outside during the summer months. There may be an "unidentified synergism between the pollutant and a meteorological or physical factor." 

"In this study we observed evidence that ambient concentrations of ozone and primary pollutants from traffic sources independently contributed to the burden of emergency department visits for pediatric asthma," wrote Strickland. "Further, the associations were present at relatively low ambient concentrations, reinforcing the need for continued evaluation of the EPA’s National Ambient Air Quality Standards to ensure that the standards are sufficient to protect susceptible individuals."

Source: American Thoracic Society