Lack of bronchomotor response to up to 3 ppm formaldehyde in subjects with asthma

A study was undertaken to determine whether exposure to concentrations of formaldehyde occasionally encountered in polluted indoor air would cause bronchoconstriction in subjects with mild asthma. In seven subjects the increase in specific airways resistance (SR aw) caused by inhalation of 1 ppm formaldehyde for 10 min was compared with the response caused by inhalation of formaldehyde-free air. Also, the increase in SR aw caused by inhalation of 1 and 3 ppm formaldehyde during moderate exercise for 10 min was compared with the response caused by inhalation of formaldehyde-free air during exercise for 10 min. Inhalation of formaldehyde at rest and during exercise did not cause a significant increase in SR aw in the subjects. It is concluded that brief exposure to these concentrations of formaldehyde, even in association with moderate exercise, is unlikely by itself to cause significant bronchoconstriction in most subjects with mild asthma.