Association of Traffic and Railway Noise with Blood Pressure in the Swiss Air Pollution and Lung Disease in Adults Cohort (Sapaldia)

Abstract

ISEE-0366 Background: Noise exposure has been associated with cardiovascular morbidity. Studies on noise and hypertension are inconsistent, and potential confounding by air pollution remains unclear. Objective: To examine the association of traffic and railway noise exposure by day and night with blood pressure adjusting for ambient air pollution. Methods: Blood pressure was measured in 6450 SAPALDIA participants, aged 29-73. Estimates of annual average street and railway noise levels at residential addresses during day- and night-time were obtained from a model developed by the Swiss Federal Office of the Environment. Annual average outdoor air pollution exposure to PM10 and NO2 at the address of residence was predicted by dispersion/land-use regression models. Associations of systolic and diastolic blood pressure with traffic and railway noise were estimated using multivariable linear regression. Interactions were tested for age, gender, hypertension and time of residency. Results: Traffic and railway noise exposure ranged from 0-73 dBA and 0-66 dBA, respectively. Railway noise was positively associated with systolic pressure: daytime (0.060 mmHG/dBA, 95%CI 0.002-0.116), night-time (0.064, 0.003-0.131); and with diastolic pressure: daytime: (0.02, −0.0016-0.053), night-time (0.030, −0.012-0.070). Adjusting for NO2 resulted in slightly stronger associations. Interactions, with higher effect estimates, were present in elderly, men and hypertensive participants, and lower effects in participants with longer time of residency. Regression analyses on traffic noise and blood pressure yielded non-significant results. Conclusion: We found a significant association between railway noise and blood pressure after adjusting for exposure to outdoor air pollution. Contrarily to prior studies, traffic noise had no-significant impact. Adjusting for NO2 resulted in a slightly increased association. Larger noise-related increase in blood pressure was observed in men, elderly and hypertensive patients. Effect modification by time of residency may be due to natural selection of noise in-sensitive individuals or adaptation to the exposure.