Effects of air pollution and weather conditions on asthma exacerbation

Background: Meteorological conditions and a high concentration of air pollu tants have been associated with increased respiratory morbidity. However, f ew studies have examined the association between asthma exacerbation and ai r pollution. Objectives: In the present study, the possible relationship of the concentration of black smoke and SO2 in the air, the local weather con ditions and emergency room visits for asthma is investigated. Methods: The weekly total of emergency room admissions for asthmatic adults during a 1-y ear period was recorded together with daily metereological conditions (aver age temperature, humidity, rainfall, wind speed and barometric pressure) an d average weekly levels of daily pollutant concentrations (black smoke and SO2). The relationship was assessed by stepwise regression linear models an d analysis of variance. The analysis took into account season and metereolo gical variables. Results: Both air pollutants correlated significantly with emergency room admissions for asthma (SO2 [r = 0.32], black smoke [r = 0.3 5]); however, multiple regression analysis showed that black smoke was the only significant predictor of weekly visits. There were approximately 3.5 a dmissions a week per SD of change (34.6 mu g . m(-3)). There were no signif icant correlations between weekly emergency room visits and the weather var iables. Analysis of the data stratified by season and weather conditions de monstrated that the association of black smoke with asthma exacerbation was more pronounced in autumn (r = 0.67) or when temperatures were higher than average. Conclusion: In our city, a high concentration of certain air poll utants is indeed associated with an increase in the number of hospital emer gency room admissions for asthma.