Effects of air pollution and weather conditions on asthma exacerbation

Background: Meteorological conditions and a high concentration of air pollutants have been associated with increased respiratory morbidity. However, few studies have examined the association between asthma exacerbation and air pollution. Objectives: In the present study, the possible relationship of the concentration of black smoke and SO2 in the air, the local weather conditions and emergency room visits for asthma is investigated. Methods: The weekly total of emergency room admissions for asthmatic adults during a 1-year period was recorded together with daily metereological conditions (average temperature, humidity, rainfall, wind speed and barometric pressure) and average weekly levels of daily pollutant concentrations (black smoke and SO2). The relationship was assessed by stepwise regression linear models and analysis of variance. The analysis took into account season and metereological variables. Results: Both air pollutants correlated significantly with emergency room admissions for asthma (SO2 [r = 0.32], black smoke [r = 0.35]); however, multiple regression analysis showed that black smoke was the only significant predictor of weekly visits. There were approximately 3.5 admissions a week per SD of change (34.6 mu g . m(-3)). There were no significant correlations between weekly emergency room visits and the weather variables. Analysis of the data stratified by season and weather conditions demonstrated 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 pollutants is indeed associated with an increase in the number of hospital emergency room admissions for asthma.