Air pollution and asthma: effects of exposures to short-term sulfur dioxide peaks.

Recent laboratory studies have shown exposures to SO2 at levels as low as 0.1 ppm and lasting as little as 10 min to lead to changes in respiratory functions as well as symptoms in asthmatic individuals exposed during exercise. The present study was conducted to determine whether similar responses to short-term SO2 peaks in the ambient air can be detected in a free-living population. Tests were made for an association between days with SO2 peaks above various levels, as identified from hourly measurements obtained by the New York City Aerometric Network, and days with high numbers of emergency room visits for asthma at three inner-city municipal hospitals in New York City. No association was found.