Effects of 0.75ppm Sulfur Dioxide on Pulmonary Function Parameters of Normal Human Subjects

Abstract

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.

Pulmonary Function Effects of 1.0 and 2.0 ppm Sulfur Dioxide Exposure in Active Young Male Non-Smokers

“…Since 99% of SO 2 was cleared in the nasopharynx, they proposed that a nasobronchial reflex bronchoconstriction may have occurred. However, Stacy et al , 5 using two separate groups, a control vs. an exposure group exposed for 2 h to 0.75 ppm SO2 with a single 15-min exercise period, observed a tendency for increased expired flow (FEV1.0/FVC, FEF50%) both Table IV. Specific airway conductance (SGaw) following 2 h exposure to 1.0 ppm SO2 (n = 23) (mean ± standard error).…”

“…Stacy et al , 5 in their study of the response of "normal" subjects to 0.75 ppm SO2, found a significant difference between subjects exposed to air and those exposed to SO 2 in the airway resistance following exercise. Sulfur dioxide exposed subjects had a rise in Raw, while air exposed subjects exhibited a fall in Raw.…”

“…Following the initial study of nine subjects, 14 additional subjects were exposed to FA and 1.0 ppm SO 2 in an attempt to verify results obtained by Stacy et al 5 for exposure to 0.75 ppm SO2. The data for the pooled subjects (n = 23) were again analyzed using analysis of variance with repeated measures across both time and treatment (filtered air and 1.0 ppm SO2) using a more conservative alpha level of 0.01.…”

“…Stacy et al 5 have reported modest but not clearly significant changes in FEV1.0/FVC and FEF50% as well as a significant increase in Raw following exposure to 0.75 ppm SO2 for 2 h which included a single 15-min exercise period (VE = 60 L/min). The changes were more readily apparent immediately following exercise.…”

Sulfur Dioxide and Exercise: Relationships between Response and Absorption in Upper Airways

“…15 "" 19 Exercise not only increases the total volume of inspired air (and pollutants) but also reduces the efficiency of pollutant removal in the upper airways. 8 - 17 Increased SO2 penetration to tissues of the laryngopharyrix and more distal airways is expected to increase the bronchoconstrictive effects.…”