Research Program Area: Health & Exposure
A study of 14 healthy adult subjects was undertaken to determine whether brief exposure to 0.5-0.6 ppm of ozone would increase bronchial reactivity to inhaled irritants, as reflected by the rise in airway resistance provoked by aerosol challenge with weak solutions of histamine or methacholine. An additional study of nine subjects with non-asthmatic allergic diseases was also undertaken to determine the effects on ozone on bronchial reactivity in atopic subjects. Subjects from both the non-atopic and atopic groups were exposed to ozone on several occasions to determine whether tolerance develops to the sensitizing effects of ozone on bronchial responsiveness. The results indicate that exposure to 0.6 ppm of ozone for two hours increases bronchial reactivity to histamine in both normal and atopic subjects and that the increase in responsiveness is blocked by pretreatment with atropine, suggesting that postganglionic cholinergic mechanisms are involved. Bronchial reactivity returned to control levels in one to seven days in most subjects, but tolerance to repeated exposures to ozone was not observed. This work was submitted in fulfillment of contract Number A6-215-30 under the partial sponsorship of the California Air Resources Board. Work was completed as of June 30, 1978.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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