Airway response to ultra short-term exposure to ozone.

To determine whether acute short-term exposure to oxidant pollutants can cause changes in respiratory mechanics, we gave 0.5 ppm ozone for 5 min to 7 baboons. We measured pulmonary resistance (RL) and obtained dose response curves to methacholine before and after the exposures. This brief insult increased resistance (control RL = 1.53 +/- 0.21 cm H2O.L-1 s; post-ozone RL = 3.53 +/- 0.54 cm H2O.L-1 s). On a second occasion, 6 of these animals were restudied before and after the administration of cromolyn sodium. Although this drug had no effect on the measurements of mechanics made in the control period, it significantly reduced the ozone-induced changes in mechanics. The increase in RL was 52% of that produced in the first study. The results demonstrated that the ozone injury with its acute and subacute airway sequelae occurs quite rapidly and after very brief exposure. The time course of the change in mechanics and the effects of cromolyn suggest the hypothesis that surface epithelial cells are disrupted, causing subsequent release of bronchoconstricting agents.