Short-term respiratory effects of polluted ambient air: a laboratory study of volunteers in a high-oxidant community.

To investigate short-term health effects of community air pollution directly, we developed a mobile laboratory allowing "blind" exposures of volunteers to polluted ambient air and to purified air at similar temperature and humidity. Subjects (30 asthmatic, 34 normal) from the surrounding area were studied at Duarte, California, a Los Angeles suburb subject to frequent photochemical oxidant pollution. Each was exposed to a close approximation of outdoor ambient air for 2 h with intermittent light exercise. Lung function and symptoms were evaluated pre- and post-exposure. A control (purified air) study took place several weeks later. Mean ambient air exposure concentrations were near 0.22 ppm for ozone and 200 micrograms/m3 for total suspended particulate. Ambient air exposures were associated with small significant losses in forced expiratory performance and total lung capacity. The responses of asthmatic and normal subjects were generally not significantly different, possibly because many normal subjects had a history of allergy and appeared atypically reactive to respiratory insults. In the normal subjects, a small significant increase in reported symptoms was seen with ambient air exposures compared with the control. In the asthmatics, the increase was not significant. Over-all, only slight effects attributable to exposure were found, even though a severely polluted area and a presumed high-risk population were chosen for study.