Pulmonary function and maximum exercise responses following acute ozone exposure.

We examined changes in pulmonary function during resting exposure to concentrations of ozone at 0.75, 0.50, 0.25, and 0.00 parts/million (ppm), and determined the effect these exposures had on a subsequent maximum exercise test using filtered air. In order to determine if recovery of pulmonary function would be facilitated by increased ventilation due to maximum exercise, a control condition was conducted with subjects resting for a period equivalent to the maximum exercise condition. Eight males and five females participated in eight different conditions in order to answer these two questions. Resting 2-h exposure to 0.75 and 0.50 ppm ozone caused significant decrements in forced vital capacity of 10% and 5%, respectively. However, 0.00 and 0.25 ppm ozone induced no pulmonary decrement. None of the pollutant conditions reduced subsequent maximum exercise performance (ml O2.min-1.kg-1, heart rate, and total performance time). The pulmonary function responses after the maximum capacity test returned to pre-ozone values for the 0.50 ppm condition, but were still significantly decreased for the 0.75 ppm condition. The increased ventilatory exchanges from maximum exercise did not facilitate the return of pulmonary function. It appeared that increased ventilation during ozone exposure plays a significant role only in inducing pulmonary function decrement, but not in facilitating the return of pulmonary function to normal values.