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.

Associations of particulate matter and daily mortality in Bangkok, Thailand.

The association between airborne particles and daily mortality has been reported in many locations, but mainly in western countries. There is a need to investigate the association in locations where the emission sources, weather, and other environmental conditions differ from those in western countries. In this study, the acute effects of PM10 and visibility on daily mortality in Bangkok, Thailand, from 1992 to 1997, were examined. A Poisson regression model was developed to estimate the excess daily mortality associated with PM10 and visibility, while controlling for long-term trends, season, and variations in weather. It was found that increasing PM10 and decreasing visibility levels were independently associated with increasing daily mortality from all non-external causes, cardiovascular, respiratory, and other diseases. The observed associations were stronger for respiratory diseases than for cardiovascular and other diseases and were stronger for persons aged > or = 65 years than for those in the younger age group. The results of the PM10/mortality and visibility/mortality models were consistent, suggesting that visibility may be considered as a surrogate marker for the assessment of the adverse health effects of fine particulate matter when data from direct gravimetric measurements are not available.