title: Ambient air pollution exposures and risk of rheumatoid arthritis: results from the Swedish EIRA case-control study.
abstract: OBJECTIVE
  Environmental factors may play a role in the development of rheumatoid arthritis (RA). We examined whether long-term exposures to air pollution were associated with the risk of RA in the Swedish Epidemiological Investigation of Rheumatoid Arthritis Study.
  
  
  METHODS
  We studied 1497 incident RA cases and 2536 controls. Local levels of particulate matter (PM10) and gaseous pollutants (sulphur dioxide (SO2) and nitrogen dioxide (NO2)) from traffic and home heating were predicted for all residential addresses. We examined the association of an IQR increase (2 µg/m3 for PM10, 8 µg/m3 for SO2 and 9 µg/m3 for NO2) in each pollutant at different time points before symptom onset and average exposure with the risk of all RA and the risk of the rheumatoid factor and anti-citrullinated protein antibody (ACPA) RA phenotypes.
  
  
  RESULTS
  There was no evidence of an increased risk of RA with PM10. Total RA risks were modestly elevated for the gaseous pollutants, but were not statistically significant after adjustment for smoking and education (OR 1.18, 95% CI 0.97 to 1.43 and OR 1.09, 95% CI 0.99 to 1.19 for SO2 and NO2 in the 10th year before onset). Stronger elevated risks were observed for individuals with less than a university education and with the ACPA-negative RA phenotype.
  
  
  CONCLUSIONS
  No consistent overall associations between air pollution in the Stockholm area and the risk of RA were observed. However, there was a suggestion of increased risks of RA incidence with increases in NO2 from local traffic and SO2 from home heating sources with stronger associations for the ACPA-negative phenotype.
authors: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. Jaime.hart@channing.harvard.edu
authors: Jaime E
authors: JE
authors: Hart
authors: Henrik
authors: H
authors: Källberg
authors: Francine
authors: F
authors: Laden
authors: Tom
authors: T
authors: Bellander
authors: Karen H
authors: KH
authors: Costenbader
authors: Marie
authors: M
authors: Holmqvist
authors: Lars
authors: L
authors: Klareskog
authors: Lars
authors: L
authors: Alfredsson
authors: Elizabeth W
authors: EW
authors: Karlson
mesh_terms: D000328:Adult; D000397:Air Pollution / Q000032:analysis* / Q000706:statistics & numerical data; D001172:Arthritis, Rheumatoid / Q000453:epidemiology*; D016022:Case-Control Studies; D004522:Educational Status; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000032:analysis*; D016017:Odds Ratio; D052638:Particulate Matter / Q000032:analysis*; D012307:Risk Factors; D013458:Sulfur Dioxide / Q000032:analysis*; D013548:Sweden / Q000453:epidemiology
chemical_list: D052638:Particulate Matter; D013458:Sulfur Dioxide; D009585:Nitrogen Dioxide