Risk of hypertension from exposure to road traffic noise in a population-based sample

To assess the association between hypertension and traffic noise.

The prevalence and incidence of hypertension were examined in a Swedish municipality partly affected by noise from a highway (20,000 vehicles/24 h) and a railway (200 trains/24 h). A-weighed 24 h average sound levels (L(Aeq,24h)) from road and railway traffic were calculated at each residential building using a geographical information system and a validated model. Physician-diagnosed hypertension, antihypertensive medication and background factors were evaluated in 1953 individuals using postal questionnaires (71% response rate). Prevalence ratios and odds ratios (ORs) were calculated for different noise categories. Based on year of moving into the residence and year of diagnosis, person-years and incidence rates of hypertension were estimated, as well as relative risks including covariates, using Poisson and Cox regression.

When road traffic noise, age, sex, heredity and body mass index were included in logistic regression models, and allowing for >10 years of latency, the OR for hypertension was 1.9 (95% CI 1.1 to 3.5) in the highest noise category (56-70 dBA) and 3.8 (95% CI 1.6 to 9.0) in men. The incidence rate ratio was increased in this group of men, and the relative risk of hypertension in a Poisson regression model was 2.9 (95% CI 1.4 to 6.2). There were no clear associations in women or for railway noise.

The study shows a positive association between residential road traffic noise and hypertension among men, and an exposure-response relationship. While prevalence ratios were increased, findings were more pronounced when incidence was assessed.