Journal of Applied Physiology, Vol 58, Issue 6 1783-1787, Copyright © 1985 by American Physiological Society
Pulmonary response to threshold levels of sulfur dioxide (1.0 ppm) and ozone (0.3 ppm)
L. J. Folinsbee, J. F. Bedi and S. M. Horvath
We exposed 22 healthy adult nonsmoking male subjects for 2 h to filtered
air, 1.0 ppm sulfur dioxide (SO2), 0.3 ppm ozone (O3), or the combination
of 1.0 ppm SO2 + 0.3 ppm O3. We hypothesized that exposure to
near-threshold concentrations of these pollutants would allow us to observe
any interaction between the two pollutants that might have been masked by
the more obvious response to the higher concentrations of O3 used in
previous studies. Each subject alternated 30-min treadmill exercise with
10-min rest periods for the 2 h. The average exercise ventilation measured
during the last 5 min of exercise was 38 1/min (BTPS). Forced expiratory
maneuvers were performed before exposure and 5 min after each of the three
exercise periods. Maximum voluntary ventilation, He dilution functional
residual capacity, thoracic gas volume, and airway resistance were measured
before and after the exposure. After O3 exposure alone, forced expiratory
measurements (FVC, FEV1.0, and FEF25-75%) were significantly decreased. The
combined exposure to SO2 + O3 produced similar but smaller decreases in
these measures. There were small but significant differences between the O3
and the O3 + SO2 exposure for FVC, FEV1.0, FEV2.0, FEV3.0, and FEF25-75% at
the end of the 2-h exposure. We conclude that, with these pollutant
concentrations, there is no additive or synergistic effect of the two
pollutants on pulmonary function.
