Pulmonary function and sulphur dioxide, some preliminary findings.

In an extensive series of experiments, involving a total of twenty-five healthy normal subjects, increases in airways resistance have been seen when low concentrations (1–3 ppm) of SO₂ have been inhaled deeply, and after higher concentrations (5–30 ppm) have been inhaled normally. Deep breathing was used to increase the inspiratory velocity to overcome absorption in the upper respiratory tract, thereby achieving better penetration of the SO₂ into the lung. A wide range of sensitivities to SO₂ was found among the subjects, and in general, the changes in airways resistance were short-lived. The relevance of these results to the effects of urban atmospheres containing SO₂ is discussed.