Childhood asthma hospitalizations and ambient air sulfur dioxide concentrations in Bronx County, New York.

The association between asthma hospitalizations and ambient sulfur dioxide (SO2) concentrations was examined in a case-control study in Bronx County, New York. Cases comprised 2629 children aged 0-14 yr who were admitted to hospitals for asthma. There were 2236 controls who were admitted for reasons other than asthma. Daily ambient SO2 concentrations were categorized into quartiles of both average and maximum levels and various exposure windows (i.e., day of admission and 1-, 2-, and 3-d lags). Cases were exposed to higher daily average concentrations of SO2 than controls. The authors compared the highest exposure quartile with the lowest, and the odds ratios were 1.66, 1.90, 2.05, and 2.21 (all p < 0.01 for same-day, 1-, 2-, and 3-d lags, respectively), with a similar finding for daily SO2 maximum exposure. The results suggest a consistent positive association between SO2 exposure and hospitalizations for childhood asthma.