Pulmonary function and symptom responses after 6.6-hour exposure to 0.12 ppm ozone with moderate exercise.

Abstract

Episodes occasionally occur when ambient ozone (O3) levels remain at or near 0.12 ppm for more than 6 h. Small decrements In lung function have been reported following 2-h exposures to 0.12 ppm O3. For short exposures to higher O3 concentrations, lung function decrements are a function of exposure duration. Thus, we investigated the hypothesis that prolonged exposure to 0.12 ppm O3 would result in progressively larger changes in respiratory function and symptoms over time. Ten nonsmoking males (18-33 yr) were exposed once to clean air and once to 0.12 ppm O3 for 6.6 h. Exposures consisted of six 50-min exercise periods, each followed by 10-min rest and measurement; a 35-min lunch period followed the third exercise period. Exercise ventilation averaged approximately 40 L/min. Forced expiratory and inspiratory spirometry and respiratory symptoms were measured prior to exposure and after each exercise. Airway reactivity to methachollne was determined after each exposure. After correcting for the air exposure...