Effects of acute controlled exposure to SO₂ on respiratory mechanics in healthy male adults

¹ Departments of Physiology and Biostatistics, Harvard School of Public Health, Boston, Massachusetts

Eleven healthy, adult, male volunteers were exposed on separate occasions to average levels of sulfur dioxide of 1, 5, and 13 ppm. The subjects were seated in a body plethysmograph, breathing spontaneously by mouth while measurements of respiratory mechanics were made with an esophageal catheter. Exposures lasted 10–30 min and, for each subject, were spaced at least 1 month apart. With one exception the group showed no significant increase in pulmonary flow resistance at the lowest concentration of gas. At both 5 and 13 ppm, flow resistance was elevated, the change being greater at 13 ppm. The change occurred within 1 min of exposure, increased after 5 min but, on the average, showed no further change after 10 min. Four subjects were exposed to 5 or 13 ppm of SO₂ for 30 min without exhibiting increases in flow resistance beyond the 1st 10 min. There were no consistent changes in pulmonary compliance, tidal volume, breathing frequency, or pulse rate. The functional residual capacity increased slightly during exposure to 13 ppm.

Note:
(With the Technical Assistance of Eleanor Root)

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