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PROPORTION OF MODERATELY EXERCISING INDIVIDUALS RESPONDING TO LOW-LEVEL, MULTI-HOUR OZONE EXPOSURE
Citation:
McDonnell, W., P. Stewart, S. Andeoni, AND M. Smith. PROPORTION OF MODERATELY EXERCISING INDIVIDUALS RESPONDING TO LOW-LEVEL, MULTI-HOUR OZONE EXPOSURE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-95/537.
Description:
The purpose of this study was to describe the proportion of moderately exercising individuals experiencing significant respiratory responses to low-level, multi-hour ozone exposure as a function of ozone concentration and exposure duration. ixty-eight healthy, nonsmoking adults, ages 18-34 years underwent two or more 6.6 hour exposures to 0.0, 0.08, 0.10, or 0.12 part per million ozone. ive hours of exercise was performed during exposure, and lung function was measured before exposure and following each hour of exposure. or each combination of concentration and duration, each individual was determined to either have or not have experienced a 1001 or greater decrement in FEVI. ogistic function was used to model the proportion of individuals experiencing such a decrement as a function of concentration and exposure duration. ootstrap 900 confidence intervals (CI) were calculated around the predictions. he model was found to give predictions which were in good agreement with observed data. he lowest level of exposure (CxT) for which the 90% CI excluded zero was approximately 0.2 ppm-hr. or exposure to 0.12 ppm ozone for 6.6 hours, 47% (9001 CI= 30-65%) of exposed individuals were predicted to experience a 10% decrement. reater proportion of younger adults was found to experience a given effect for a given exposure than older adults.