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U.S. Department of Energy
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Airway hyperirritability induced by ozone. II. Report for 26 September 1978-26 December 1979

Technical Report ·
OSTI ID:5455459

In 19 healthy adult subjects a 2-h exposure to 0.4 ppM but not to 0.2 ppM of ozone significantly increased the rise in resistance provoked by inhalation of histamine. With three repeated 2-h exposures of 0.4 ppM of ozone on consecutive days, however, the bronchomotor response to histamine progressively decreased, ultimately returning to pre-exposure levels. Thus, the threshold level of ozone causing an increase in bronchial reactivity in healthy human subjects is between 0.2 and 0.4 ppM; tolerance to this effect of ozone develops with repeated exposures. The authors also studied the relationship between bronchomotor responsiveness to histamine and the response to inhalation of SO2. Three subjects showed no change in the response to 5 ppM of SO2 after a 2-h exposure to 0.6 ppM of ozone; but subjects with mild, asymptomatic asthma, who had preexisting bronchial hyperreactivity to histamine, showed significant bronchomotor response to 10-min inhalation of 1,3, and 5 ppM of SO2, whereas normal and atopic subjects responded only to 5 ppM of SO2. Response to SO2 was blocked by pre-treatment with atropine, suggesting the involvement of postganglionic cholinergic pathways; it did not correlate with the response to histamine, suggesting that these agents exert their effects via different pathways.

Research Organization:
California Univ., San Francisco (USA). School of Medicine; California State Air Resources Board, Sacramento (USA)
OSTI ID:
5455459
Report Number(s):
PB-82-113226
Country of Publication:
United States
Language:
English