Road traffic noise, air pollution and myocardial infarction: a prospective cohort study

Both road traffic noise and air pollution have been linked to cardiovascular disease. However, there are few prospective epidemiological studies available where both road traffic noise and air pollution have been analyzed simultaneously. The aim of this study was to investigate the relation between road traffic noise, air pollution and incident myocardial infarction in both current (1-year average) and medium-term (3-year average) perspective. This study was based on a stratified random sample of persons aged 18-80 years who answered a public health survey in SkAyenne, Sweden, in 2000 (n = 13,512). The same individuals received a repeated survey in 2005 and 2010. Diagnoses of myocardial infarction (MI) were obtained from medical records for both inpatient and outpatient specialized care. The endpoint was first MI during 2000-2010. Participants with prior myocardial infarction were excluded at baseline. Yearly average levels of noise (L (DEN)) and air pollution (NO (x) ) were estimated using geographic information system for residential address every year until censoring. The mean exposure levels for road traffic noise and air pollution in 2005 were L (DEN) 51 dB(A) and NO (x) 11 A mu g/m(3), respectively. After adjustment for individual confounders (age, sex, body mass index, smoking, education, alcohol consumption, civil status, year, country of birth and physical activity), a 10-dB(A) increase in current noise exposure did not increase the incidence rate ratio (IRR) for MI, 0.99 (95 % CI 0.86-1.14). Neither did a 10-mu g/m(3) increase in current NO (x) increase the risk of MI, 1.02 (95 % CI 0.86-1.21). The IRR for MI associated with combined exposure to road traffic noise > 55 dB(A) and NO (x) > 20 A mu g/m(3) was 1.21 (95 % CI 0.90-1.64) compared to < 55 dB(A) and < 20 A mu g/m(3). This study did not provide evidence for an increased risk of MI due to exposure to road traffic noise or air pollution at moderate average exposure levels.