Effects of inhaled sulfur dioxide (SO2) on pulmonary function in healthy adolescents: exposure to SO2 alone or SO2 + sodium chloride droplet aerosol during rest and exercise.

Recently we reported statistically significant changes in pulmonary functional measurements in asthmatic adolescents exposed at rest or during exercise. To demonstrate whether those results were due to the subjects' adolescence, or more likely, to their diagnosis of asthma, we repeated identical exposures in healthy adolescents. The changes after exposure to sulfur dioxide (SO2); however the changes were only slightly greater than those seen after sham exposure. After exposure at rest to 1.0 ppm SO2 + 1 mg/m3 sodium chloride (NaCl) droplet aerosol, the healthy adolescents showed small (3%) but statistically significant reductions in forced expiratory volume in one second (FEV1.0). No significant changes were seen following exposure to NaCl of SO2 alone at rest. Exposure to the SO2 modes during moderate exercise produced greater changes. Following exposure to either the SO2 + NaCl mixture or 1.0 ppm of SO2 alone, the reductions in FEV1.0 were slightly greater (6%) and prolonged compared with those seen at rest. Significant decreases also were seen in Vmax50 and Vmax75. A small decrease (4%) in FEV1.0 was seen following exposure to NaCl alone during exercise, but the change was not statistically significant. The changes seen in the healthy adolescents were slight compared to those seen in the asthmatic adolescents previously exposed (changes of 23-67%). We conclude that asthmatic adolescents are much more sensitive to the effects of inhaled SO2 than are healthy adolescents.