title: Association of long-term exposure to traffic-related air pollution with blood pressure and hypertension in an adult population-based cohort in Spain (the REGICOR study).
abstract: BACKGROUND
  Long-term exposure to traffic-related air pollution may increase blood pressure (BP) and induce hypertension. However, evidence supporting these associations is limited, and they may be confounded by exposure to traffic noise and biased due to inappropriate control for use of BP-lowering medications.
  
  
  OBJECTIVE
  We evaluated the associations of long-term traffic-related air pollution with BP and prevalent hypertension, adjusting for transportation noise and assessing different methodologies to control for BP-lowering medications.
  
  
  METHODS
  We measured systolic (SBP) and diastolic BP (DBP) at baseline (years 2003-2005) in 3,700 participants, 35-83 years of age, from a population-based cohort in Spain. We estimated home outdoor annual average concentrations of nitrogen dioxide (NO2) with a land-use regression model. We used multivariate linear and logistic regression.
  
  
  RESULTS
  A 10-μg/m3 increase in NO2 levels was associated with 1.34 mmHg (95% CI: 0.14, 2.55) higher SBP in nonmedicated individuals, after adjusting for transportation noise. Results were similar in the entire population after adjusting for medication, as commonly done, but weaker when other methods were used to account for medication use. For example, when 10 mmHg were added to the measured SBP levels of medicated participants, the association was β = 0.78 (95% CI: -0.43, 2.00). NO2 was not associated with hypertension. Associations of NO2 with SBP and DBP were stronger in participants with cardiovascular disease, and the association with SBP was stronger in those exposed to high traffic density and traffic noise levels ≥ 55 dB(A).
  
  
  CONCLUSIONS
  We observed a positive association between long-term exposure to NO2 and SBP, after adjustment for transportation noise, which was sensitive to the methodology used to account for medication.
authors: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain.
authors: Maria
authors: M
authors: Foraster
authors: Xavier
authors: X
authors: Basagaña
authors: Inmaculada
authors: I
authors: Aguilera
authors: Marcela
authors: M
authors: Rivera
authors: David
authors: D
authors: Agis
authors: Laura
authors: L
authors: Bouso
authors: Alexandre
authors: A
authors: Deltell
authors: Jaume
authors: J
authors: Marrugat
authors: Rafel
authors: R
authors: Ramos
authors: Jordi
authors: J
authors: Sunyer
authors: Joan
authors: J
authors: Vila
authors: Roberto
authors: R
authors: Elosua
authors: Nino
authors: N
authors: Künzli
mesh_terms: D000393:Air Pollutants / Q000633:toxicity; D000397:Air Pollution / Q000009:adverse effects*; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000139:chemically induced; D008297:Male; D009585:Nitrogen Dioxide / Q000633:toxicity; D013030:Spain
chemical_list: D000393:Air Pollutants; D009585:Nitrogen Dioxide