Fig. 1.

Study design. Subjects were exposed to 0, 100, and 200 ppb ozone (O₃) in random order for 4 h with intermittent exercise in a repeated measure design. Electrocardiogram recording, phlebotomy, and spirometry were obtained immediately before (0 h), immediately after (4 h), and 20 h after (24 h) each exposure. Bronchoscopy with bronchoalveolar lavage (BAL) was performed at 24-h time point. The exposures were at least 3 wk apart to allow for recovery from previous exposure.