Effect of ambient air pollution on acute exacerbations in adult patients with asthma

Abstract

Background: Outdoor air pollution is one of the important risk factors for both development of asthma and acute exacerbation. Although some epidemiologic studies have shown that increased levels of air pollutants are linked with acute exacerbations, there are few studies estimating the effects of individual air pollutants on exacerbation especially in Korea. Method: We evaluated the relative risk of acute exacerbation due to increase of each air pollutants levels. We enrolled patients with asthma living in Seoul, who visited the emergency room (ER) of Hanyang University Hospital for aggravation of asthmatic symptoms from 1 January 2005 to 31 December 2005. The daily average levels of air pollutants were retrieved from data collected by routine monitoring for gaseous air pollutants [sulfur dioxide, nitrogen dioxide (NO2), ozone, carbon monoxide and for airborne particles less than or equal to 10 μm in diameter (PM10)]. A case-crossover analysis was performed using levels of air pollutants at two weeks before and after ER visit as controls. Results: The estimated relative risk (RR) of ER visit for asthma was higher for NO2 although statistical significance was lacking. There was no significant increase of RR for other measured pollutants. Conclusion: Risk of ER visit was not associated with the level of ambient air pollutants in adult patients with asthma. Further large scale studies are needed to confirm effects of these air pollutants on asthma exacerbation.