Acute effects of SO2 and particles from a power plant on respiratory symptoms of children, Thailand.

Epidemiological studies to evaluate the acute effects of ambient SO2 on the respiratory health of children provide inconclusive results. A panel study to examine the association of short-term exposure to ambient SO2 and respiratory symptoms of 196 children for a period of 107 days was conducted in Thailand. Generalized Estimating Equations were used to examine the association of daily variation of air pollution with daily respiratory symptoms. During the study period, SO2 was not associated with respiratory symptoms in either asthmatics or non-asthmatics, whereas a 10 microg/m3 increase in PM10 was modestly associated with increases of lower respiratory symptom incidence (OR=1.03, 95%CI=0.98, 1.09) and cough (OR=1.04, 95% CI=1.00, 1.08) in asthmatics. At the low ambient air pollution concentrations observed, particulate matter rather than SO2 was associated on a microg/m3 basis with acute daily respiratory symptoms.