title: Ozone is associated with an increased risk of respiratory exacerbations in patients with cystic fibrosis.
abstract: 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 São 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 (O3), 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 O3 concentration (45.62 μg/m3) 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.
authors.affiliation: Emergency Unit, Laboratory of Experimental Air Pollution, University of São Paulo Medical School, São Paulo; Children's Institute, Clinics Hospital and the Environmental Epidemiology Study Group, Laboratory of Experimental Air Pollution, University of São Paulo Medical School, São Paulo. Electronic address: sylvia.farhat@gmail.com.
authors.forename: Sylvia C L
authors.initials: SCL
authors.lastname: Farhat
authors.affiliation: Pulmonology Unit, Laboratory of Experimental Air Pollution, University of São Paulo Medical School, São Paulo.
authors.forename: Marina B
authors.initials: MB
authors.lastname: Almeida
authors.affiliation: Pulmonology Unit, Laboratory of Experimental Air Pollution, University of São Paulo Medical School, São Paulo; Virology Laboratory, Tropical Medicine Institute, University of São Paulo, São Paulo.
authors.forename: Luiz Vicente R F
authors.initials: LVRF
authors.lastname: Silva-Filho
authors.affiliation: Children's Institute, Clinics Hospital and the Environmental Epidemiology Study Group, Laboratory of Experimental Air Pollution, University of São Paulo Medical School, São Paulo.
authors.forename: Juliana
authors.initials: J
authors.lastname: Farhat
authors.affiliation: Pulmonology Unit, Laboratory of Experimental Air Pollution, University of São Paulo Medical School, São Paulo.
authors.forename: Joaquim C
authors.initials: JC
authors.lastname: Rodrigues
authors.affiliation: Children's Institute, Clinics Hospital and the Environmental Epidemiology Study Group, Laboratory of Experimental Air Pollution, University of São Paulo Medical School, São Paulo; Environmental Exposure and Risk Assessment, Collective Health Post-graduation Program, Catholic University of Santos, Santos, Brazil.
authors.forename: Alfésio L F
authors.initials: ALF
authors.lastname: Braga
mesh_terms: D000293:Adolescent; D000393:Air Pollutants / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000150:complications*; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D010126:Ozone / Q000009:adverse effects*; D012140:Respiratory Tract Diseases / Q000139:chemically induced* / Q000453:epidemiology; D018570:Risk Assessment
chemical_list: D000393:Air Pollutants; D010126:Ozone