Respiratory symptoms and air pollution changes in children: the Gardanne Coal-Basin Study

The influence of daily changes in sulfur dioxide (SO2) levels on the induction of respiratory symptoms was studied during the 1983-1984 winter in 450 children, aged 9 to 11 yr, living in the Gardanne coal-basin, France. In this area, SO2 originates mainly from a coal-fueled power plant. The mean SO2 level during the winter was 22 micrograms/m3 in low-pollution areas and 93 micrograms/m3 in polluted areas, with daily SO2 levels up to 356 micrograms/m3. Children completed a daily diary about respiratory symptoms. In the polluted communities only we demonstrated a significant association between daily SO2 levels (after controlling for temperature and respirable particle variations) and prevalence of upper and lower respiratory symptoms. However, in each polluted town, and for each respiratory symptom, there was no evidence for either a latency period or a delay in the effects of pollutants. Mean daily temperature was also closely correlated with upper and lower respiratory symptoms in most of the polluted and some low-pollution communities. In a second step, the prevalence of respiratory symptoms in each town was compared, during two 2-wk periods, with air pollution levels; higher prevalences were found during the pollution period. In conclusion, moderate daily changes in SO2 levels induce a significant but transient increase in the prevalence of respiratory symptoms in children.