Respiratory effects of exposure to ozone plus sulfur dioxide in Southern Californians and Eastern Canadians

Abstract

Volunteer subjects were exposed in an environmentally controlled chamber in Los Angeles [California, USA] to SO2 and O3, separately and in combination, to study the enhanced toxicity of the O3 + SO2 mixture observed in a previous study in Montreal [Canada]. Toxic responses to O3 + SO2 were less severe than observed previously, and only slightly more severe than with O3 alone. S-containing aerosols formed by chemical reactions within the chamber air may have contributed to the O3 + SO2 responses in the Montreal study. Adaptation of Los Angeles residents to ambient O3 may also contribute to response variability.