Controlled human studies on the pulmonary effects of indoor air pollution: Experiences with sulful dioxide and formaldehyde

We have studied the acute pulmonary effects of low-level exposure to sulfur dioxide (SO₂) [0-1.0 μL/L] and formaldehyde (FA) [0 and 2 μL/L] in a controlled environmental chamber. Both healthy and asthmatic subjects were tested at rest and with moderate activity. Lung function changes (partial and maximal flow-volume curves) were confined to SO₂ exposure with activity in asthmatics. Neither group demonstrated an untoward lung function response to FA. Respiratory symptoms were mild to moderate from both pollutants and did not persist when measured up to 24 h after exposure. A discussion of differences seen in the responses between the groups tested, activity of subjects, and the pollutants themselves is provided.