title: Long-term exposure to outdoor air pollution and the incidence of chronic obstructive pulmonary disease in a national English cohort.
abstract: OBJECTIVE
  The role of outdoor air pollution in the incidence of chronic obstructive pulmonary disease (COPD) remains unclear. We investigated this question using a large, nationally representative cohort based on primary care records linked to hospital admissions.
  
  
  METHODS
  A cohort of 812 063 patients aged 40-89 years registered with 205 English general practices in 2002 without a COPD diagnosis was followed from 2003 to 2007. First COPD diagnoses recorded either by a general practitioner (GP) or on admission to hospital were identified. Annual average concentrations in 2002 for particulate matter with an aerodynamic diameter <10 µm (PM10) and <2.5 µm (PM2.5), nitrogen dioxide (NO2), ozone and sulfur dioxide (SO2) at 1 km(2) resolution were estimated from emission-based dispersion models. Hazard ratios (HRs) per interquartile range change were estimated from Cox models adjusting for age, sex, smoking, body mass index and area-level deprivation.
  
  
  RESULTS
  16 034 participants (1.92%) received a COPD diagnosis from their GP and 2910 participants (0.35%) were admitted to hospital for COPD. After adjustment, HRs for GP recorded COPD and PM10, PM2.5 and NO2 were close to unity, positive for SO2 (HR=1.07 (95% CI 1.03 to 1.11) per 2.2 µg/m(3)) and negative for ozone (HR=0.94 (0.89 to 1.00) per 3 µg/m(3)). For admissions HRs for PM2.5 and NO2 remained positive (HRs=1.05 (0.98 to 1.13) and 1.06 (0.98 to 1.15) per 1.9 µg/m(3) and 10.7 µg/m(3), respectively).
  
  
  CONCLUSIONS
  This large population-based cohort study found limited, inconclusive evidence for associations between air pollution and COPD incidence. Further work, utilising improved estimates of air pollution over time and enhanced socioeconomic indicators, is required to clarify the association between air pollution and COPD incidence.
authors.affiliation: Population Health Research Institute and MRC-PHE Centre for Environment and Health, St George's, University of London, London, UK.
authors.forename: R W
authors.initials: RW
authors.lastname: Atkinson
authors.affiliation: Population Health Research Institute and MRC-PHE Centre for Environment and Health, St George's, University of London, London, UK.
authors.forename: I M
authors.initials: IM
authors.lastname: Carey
authors.affiliation: Ricardo-AEA Ltd., Harwell IBC, Didcot, Oxfordshire, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Kent
authors.affiliation: London School of Hygiene and Tropical Medicine, London, UK Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: T P
authors.initials: TP
authors.lastname: van Staa
authors.affiliation: Population Health Research Institute and MRC-PHE Centre for Environment and Health, St George's, University of London, London, UK MRC-PHE Centre for Environment and Health, King's College London, UK.
authors.forename: H R
authors.initials: HR
authors.lastname: Anderson
authors.affiliation: Population Health Research Institute and MRC-PHE Centre for Environment and Health, St George's, University of London, London, UK.
authors.forename: D G
authors.initials: DG
authors.lastname: Cook
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000633:toxicity*; D000397:Air Pollution / Q000009:adverse effects*; D048729:Anacardic Acids / Q000633:toxicity; D015331:Cohort Studies; D004739:England / Q000453:epidemiology; D005260:Female; D058006:General Practice / Q000706:statistics & numerical data; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000633:toxicity; D010316:Particle Size; D052638:Particulate Matter / Q000633:toxicity; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology* / Q000209:etiology; D012307:Risk Factors; D013458:Sulfur Dioxide / Q000633:toxicity; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D048729:Anacardic Acids; D052638:Particulate Matter; C555880:ozocardic A; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide