Effects of 0.75ppm sulfur dioxide on pulmonary function parameters of normal human subjects

Of 31 young, health male volunteers who participated in this study 15 were exposed to air (control) and 16 to 0.75ppm (2.15mg/m3) SO2 for 2 hr at 21 degrees C and 60% relative humidity. At the end of the first hour, the subjects exercised for 15 min on a treadmill at 6.4 kmph, with a 10% grade. Methods employed in evaluation of pulmonary function included body plethysmography, spirometry, and multigas rebreathing test. From the battery of 15 pulmonary function parameters, only the pattern of airway resistance changes was significantly altered by SO2 exposure, although spirometric parameters followed a similar pattern. Eight of the SO2-exposed ubjects, with one or more positive allergen skin tests, appeared to be significantly more reactive to SO2 than skin test-negative subjects. All subjects remained asymptomatic. The small number of changes observed appeared to be reversible and do not suggest a significant health hazard to normal human subjects exposed to SO2 under these conditions.