ABSTRACT
BACKGROUND: Epidemiological studies have shown reversible declines of lung function in response to air pollution, but research on the independent effect of short-term exposure to ambient sulphur dioxide (SO2) on pulmonary function is limited. This study evaluated the association of short-term exposure to increased ambient SO2 and daily pulmonary function changes among children with and without asthma. METHODS: The associations of daily exposure to SO2 and particulate matter 10 microm in diameter (PM10) with pulmonary function were examined in 175 asthmatic and non-asthmatic children aged 6-14 years who resided near a coal-fired power plant in Thailand. Each child performed daily pulmonary function tests during the 61-day study period. General linear mixed models were used to estimate the association of air pollution and pulmonary function controlling for time, temperature, co-pollutants, and autocorrelation. RESULTS: In the asthmatic children, a daily increase in SO2 was associated with negligible declines in pulmonary function, but a small negative association was found between PM10 and pulmonary function. A 10-microg/m(3) increment was associated with changes in the highest forced vital capacity (FVC) (-6.3 ml, 95% CI: -9.8, -2.8), forced expiratory volume at 1 second (FEV(1)) (-6.0 ml, 95% CI: -9.2, 2.7), peak expiratory flow rate (PEFR) (-18.9 ml.sec(-1), 95% CI: -28.5, -9.3) and forced expiratory flow 25 to 75% of the FVC (FEF(25-75%)) (-3.7 ml.sec(-1), 95% CI: -10.9, 3.5). No consistent associations between air pollution and pulmonary function were found for non-asthmatic children. CONCLUSION: Declines in pulmonary function among asthmatic children were associated with increases in particulate air pollution, rather than with increases in SO2.
