Is there an association between lifetime cumulative exposure and acute pulmonary responses to ozone?

Objective: To investigate the potential effects of lifetime cumulative ozone (O-3) exposure on acute pulmonmy responses to O-3. Methods: Fifteen healthy subjects from a larger cohort of young adults were exposed to 200ppb O-3 for 4 hours followed by bronchoscopy and bronchoalveolar lavage 18 hours later. Lung-function, symptom questionnaires, and blood samples were obtained before and after each exposure. Subjects' lifetime cumulative O-3 exposures were estimated from residential histories and air-quality monitoring data. Results: Acute exposure to O-3 caused decrements in forced expiratory volume in I second (FEV1), maximal mid-expiratory flow rate (FEF25-75), and forced expiratory flow rate at 75% of forced vital capacity (FEF75), and an increase in plasma clara cell protein (CC] 6) level. Changes in CC] 6 and lower respiratory symptoms, but not in lung function, were positively correlated with lifetime cumulative O-3 exposure. Conclusion: Higher lifetime cumulative O-3 exposure was associated with airway injury and respiratory symptom responses, but not with airway inflammatory or lung function responses, to acute O-3 exposure.