Background: An association has been reported between long-term exposure to road traffic noise and the risk of myocardial infarction (MI), but the evidence is limited and inconclusive. No previous study has simultaneously analyzed the role of exposure to noise and air pollution from road traffic in the risk of MI.
Methods: A population-based case-control study on MI was conducted 1992-1994 in Stockholm County. Participants answered a questionnaire and underwent a physical examination. Residential exposure to noise and air pollution from road traffic between 1970 and 1992-1994 was assessed for 3666 participants (1571 cases of MI and 2095 controls), based on residential history combined with information on traffic intensity and distance to nearby roads. Information was also obtained on factors potentially affecting the relationship between noise exposure and MI, such as noise annoyance.
Results: The correlation between long-term individual exposure to noise and air pollution from traffic was high (r = 0.6). The adjusted odds ratio for MI associated with long-term road traffic noise exposure of 50 dBA or higher was 1.12 (95% confidence interval = 0.95-1.33). In a subsample, defined by excluding persons with hearing loss or exposure to noise from other sources, the corresponding odds ratio was 1.38 (1.11-1.71), with a positive exposure-response trend. No strong effect modification was apparent by sex or cardiovascular risk factors, including air pollution from road traffic.
Conclusions: The results lend some support to the hypothesis that long-term exposure to road traffic noise increases the risk for MI.