SELECTED ARTICLES FROM THE RECENT LITERATURE 2003

11/4/03

Prospective study of air pollution and bronchitic symptoms in asthmatic children

Summary
It has been long considered that high airborne levels of air pollutants may be a significant aggravating factor in asthma, particularly in children and elderly individuals. McConnell et al of the Univ. of Southern California in Los Angeles investigated the possible relationship of bronchitic symptoms to ambient particulate matter and to particulate elemental and organic carbon (OC), nitrogen dioxide (NO2) and other gaseous pollutants in a cohort of asthmatic children in 12 Southern California communities. They found that bronchitis symptoms (cough, sputum production), assessed yearly by questionnaires from 1996-1999, were associated with the yearly variability in the levels of a number of outdoor air pollutants, particularly within individual communities. However, the Odds Ratios for such associations of symptoms to the levels of individual pollutants were relatively modest. Nevertheless, the authors concluded that levels of organic carbon particles and nitrogen dioxide (NO2) deserve greater attention as potential causes of the chronic symptoms of bronchitis in asthmatic children. They postulated that previous cross-sectional studies might have underestimated the risks for bronchitis symptoms associated with air pollution.

Reference
Am J Respir Crit Care Med. 2003; 168:790-797

Editor's Comments
The findings of the relationship of bronchitis symptoms in asthmatic children to airborne NO2 levels, although reportedly statistically significant, are not that striking in my opinion. The situation may be not as clear-cut as implied in this current publication. In a previous study by the same investigative group they found that the relative risk for asthma development was increased considerably in children exposed to high levels of ozone during outdoor team sports. In contrast, there was no increased risk of asthma associated with the levels of NO2 or other outdoor air pollutants to which these children were exposed in their sports activities (Lancet 2002; 359:386-91).

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