Abstract
We studied the bronchial reactivity of six adult healthy male volunteers to inhaled acetylcholine (Ach) aerosol after 2-hour exposure to 0.3ppm ozone (O3) and 0.3ppm sulfur dioxide (SO2) alone and in combination. Three of the subjects showed small but significant decrease of specific airway conductance (Gaw/Vtg) after either of these exposures in comparison with control measurements. The bronchial response to inhalation of one of four concentrations of Ach aerosol immediately after exposure to these gases was significantly greater than the response in controls, among four of the subjects in O3 exposure, two of the subjects in SO2 exposure, and three of the subjects in the O3+SO2 mixture exposure. The degree of the response was relatively great after O3 exposure, but was decreased rather than enhanced by exposure to the O3+SO2 mixture. The mechanism of the decreased reactivity to inhaled Ach aerosol after exposure to the O3+SO2 mixture was not clear, although the enhanced effect on pulmonary function was usually predictably greater after exposure to the O3+SO2 mixture in comparison with the exposure to each gas alone.
