title: Contribution of smoking and air pollution exposure in urban areas to social differences in respiratory health.
abstract: BACKGROUND
  Socio-economic status, smoking, and exposure to increased levels of environmental air pollution are associated with adverse effects on respiratory health. We assessed the contribution of occupational exposures, smoking and outdoor air pollution as competing factors for the association between socio-economic status and respiratory health indicators in a cohort of women from the Ruhr area aged 55 at the time of investigation between 1985 and 1990.
  
  
  METHODS
  Data of 1251 women with spirometry and complete questionnaire information about respiratory diseases, smoking and potential confounders were used in the analyses. Exposure to large-scale air pollution was assessed with data from monitoring stations. Exposure to small-scale air pollution was assessed as traffic-related exposure by distance to the nearest major road. Socio-economic status was defined by educational level. Multiple regression models were used to estimate the contribution of occupational exposures, smoking and outdoor air pollution to social differences in respiratory health.
  
  
  RESULTS
  Women with less than 10 years of school education in comparison to more than 10 years of school education were more often occupationally exposed (16.4% vs. 10.1%), smoked more often (20.3% vs. 13.9%), and lived more often close to major roads (26.0% vs. 22.9%). Long-term exposure to increased levels of PM10 was significantly associated with lower school education. Women with low school education were more likely to suffer from respiratory symptoms and had reduced lung function. In the multivariate analysis the associations between education and respiratory health attenuated after adjusting for occupational exposure, smoking and outdoor air pollution. The crude odds ratio for the association between the lung function indicator FEV1 less than 80% of predicted value and educational level (<10 years vs. >10 years of school education) was 1.83 (95% CI: 1.22-2.74). This changed to 1.56 (95% CI: 1.03-2.37) after adjusting for occupational exposure, smoking and outdoor air pollution.
  
  
  CONCLUSIONS
  We found an association between socio-economic status and respiratory health. This can partly be explained by living conditions indicated by occupational exposure, smoking behaviour and ambient air pollution. A relevant part of the social differences in respiratory health, however, remained unexplained.
authors.affiliation: Institut für Umweltmedizinische Forschung (IUF) at the Heinrich-Heine-University of Düsseldorf, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany. tamara.schikowski@uni-duesseldorf.de
authors.forename: Tamara
authors.initials: T
authors.lastname: Schikowski
authors.forename: Dorothee
authors.initials: D
authors.lastname: Sugiri
authors.forename: Verena
authors.initials: V
authors.lastname: Reimann
authors.forename: Beate
authors.initials: B
authors.lastname: Pesch
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ranft
authors.forename: Ursula
authors.initials: U
authors.lastname: Krämer
mesh_terms: D000397:Air Pollution / Q000009:adverse effects*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D005858:Germany / Q000453:epidemiology; D006305:Health Status Indicators; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D012120:Respiration Disorders / Q000453:epidemiology*; D012129:Respiratory Function Tests; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D012959:Socioeconomic Factors; D014504:Urban Health