Abstract |
The threshold concentration of sulfur dioxide which will induce pulmonary function changes in the normal population has not been established. To investigate this question, the authors exposed nine young healthy adult non-smoking males for 2 hours to filtered air (FA), 1.0 ppm sulfur dioxide and 2.0 ppm sulfur dioxide. In a follow-up study an additional fourteen subjects were exposed to FA and 1.0 ppm sulfur dioxide conditions. Forced expiratory tests were performed prior to and following the 2 h exposure, and 5 min after each of the three 30 minute exercise periods. The work load during the exercise periods was set to elicit a minute ventilation of 40 liter BTPS. Thoracic Gas Volume (TGV), Airway Resistance (Raw), Maximal Voluntary. Ventilation (MVV) and helium dilution Functional Residual Capacity (FRC) were also measured before and after the exposure. In the initial subject group (n=9), none of the spirometric tests demonstrated any significant effects to the subject from exposure to 1.0 or 2.0 ppm of SO2 either after 30 minutes of continuous exercise or 2 hours of intermittent exercise. The only significant change (p<.05) was an increase in specific airway resistance (SRaw) following exposure to 1.0 or 2.0 ppm sulfur dioxide. However, when this observation was further studied in the larger (n=23) subject group exposed to 1.0 ppm SO2, neither SRaw nor any of the other pulmonary function test indicated a significant effect of exposure to 1.0 ppm sulfur dioxide. (Copyright (c) 1984, Air Pollution Control Association.) |