The Effects of Sulfur Dioxide on Pulmonary Function in Healthy Nonsmoking Male Subjects Aged 55 Years and Older

Abstract

To determine whether normal nonsmoking individuals aged 55 years or greater have heightened bronchial reactivity to inhaled SO₂, ten male subjects, 55 to 73 years of age, were exposed for 20 min at rest and 10 min during moderate exercise on a treadmill to the following: 1) NaCl droplet aerosol, or 2) 1.0 ppm of SO₂ and NaCl droplet aerosol. Seven of the subjects also were exposed to 0.5 ppm SO₂ and NaCl droplet aerosol. Significant decreases in forced expiratory volume in one sec (FEV₁) were seen 2-3 min post-exercise following all three test modes. The reduction in FEV₁ seen after NaCl aerosol +1.0 ppm SO₂ was significantly greater than that seen after NaCl aerosol alone. The results show that men aged 55 years or older are somewhat more sensitive to NaCl aerosol +1.0 ppm SO₂ than similarly exposed normal adolescents, but not nearly as sensitive as asthmatic subjects. This study also demonstrates that investigations of air pollutants and exercise can be undertaken in subjects of this age.