Experimental studies on human health effects of air pollutants. II. Four-hour exposure to ozone alone and in combination with other pollutant gases.

Eight adult male volunteers were exposed to ozone (O3) alone and then in combination with nitrogen dioxide and carbon monoxide under conditions simulating ambient air pollution exposures. Four "normal" men showed few or no effects from repeated exposures. Four male volunteers with a history of "hyperreactive" airways, but with normal base line pulmonary function spirometric studies, after O3 exposure developed definite symptoms and decrement in pulmonary function.