Ozone Is Associated With an Increased Risk of Respiratory Exacerbations in Patients With Cystic Fibrosis

Background: Tropospheric oxidant pollutants may injure the respiratory tract. Cystic fibrosis (CF) respiratory disease involves significant inflammation and excessive oxidative stress, and exposure to air pollutants can magnify the lung damage. The objective of this study was to investigate the association between the short-term variation in the concentration of air pollutants in metropolitan Sao Paulo, Brazil, and the occurrence of respiratory exacerbations in children and adolescents with CF. Methods: A longitudinal panel of repeated measurements was obtained from 103 patients attending the outpatient center of our institution from September 6, 2006 through September 4, 2007. Daily concentrations of inhaled particulate matter, sulfur dioxide, nitrogen dioxide, ozone (O-3), carbon monoxide, and meteorologic variables, such as the minimum temperature and relative humidity, were evaluated. The generalized estimation equation model for binomial distribution was used to assess the impact of these measurements on the occurrence of acute respiratory exacerbations. Results: In total, 103 patients with CF (median age, 8.9 years) made 408 visits, with a mean +/- SD of 4 +/- 1.74 visits per patient (range, 2-9). A respiratory disease exacerbation was diagnosed on 142 visits (38.4%). An interquartile range increase in the O-3 concentration (45.62 mu g/m(3)) had a positive, delayed (2 days after exposure) effect on the risk of a respiratory exacerbation (relative risk = 1.86; 95% CI, 1.14-3.02). Conclusions: This study demonstrates that exposure to short-term air pollution in a large urban center increases the risk of a pulmonary exacerbation in patients with CF.