NONSPECIFIC BRONCHIAL RESPONSIVENESS ASSESSED IN-VITRO FOLLOWING ACUTE INHALATION EXPOSURE TO OZONE AND OZONE SULFURIC-ACID MIXTURES

Air pollution may play some role in the recent increase in severity an d prevalence of asthma, but the specific chemical components with the ambient pollutant mix that may be responsible have not been delineated . Since ambient exposures involve mixtures, it is essential to examine airway responses to realistic pollutant mixtures. This study examined the ability of single (3-h) inhalation exposures to ozone and to mixt ures of ozone plus sulfuric acid to induce nonspecific airway hyperres ponsiveness in healthy rabbits. Airway responsiveness was assessed usi ng an in vitro assay involving administration of increasing doses of a cetylcholine to bronchial rings obtained from animals exposed to 0.1-0 .6 ppm ozone or to mixtures of ozone and 50-125 mu g/m(3) sulfuric aci d aerosol; results were compared to those reported previously for sulf uric acid alone. Bronchial hyperresponsiveness to ozone was noted foll owing exposure at all concentrations, but the combination of pollutant s results in antagonism. The results support the potential for ozone t o induce airway hyperresponsiveness in healthy animals and suggest tha t interaction with sulfuric acid may reduce the effectiveness of both pollutants.