The effects of ozone, nitrogen dioxide, and sulfur dioxide on experimentally induced allergic respiratory disorder in guinea pigs. IV. Effects on respiratory sensitivity to inhaled acetylcholine.

Most control animals inhaling acetylcholine (a chemical mediator in anaphylactic response) exhibited only labored breathing, whereas most of those pre-exposed to 30 min of >2 ppM O/sub 3/ or >50 ppM NO/sub 2/ died, presumably of bronchospasm. The fatal effect of O/sub 3/ persisted for 2 hr, disappeared at 5 hr, and reappeared at 23 hr after gas exposure. 1 ppM O/sub 3/ for 1 hr prevented the aforementioned effect of higher concentrations. Exposure of guinea pigs to concentrations of SO/sub 2/ exceeding 450 ppM did not increase mortality from acetylcholine.