Road traffic noise, air pollution and (isolated systolic) hypertension. Cross-sectional results from the KORA study.

Introduction: Cardiovascular studies on environmental noise exposure rarely considered air pollution as a covariate. Isolated systolic hypertension has not yet been in the focus of epidemiological noise studies. Methods: The association between road traffic noise and the prevalence of hypertension was assessed in 1,933 subjects aged 25-74 years living in Augsburg, Germany. Road traffic noise (weighted day-night average noise level LDN) at the facade of the dwellings was derived from noise maps. Annual averages of PM2.5 mass concentration at residential address was estimated by land-use regression method. Hypertension was assessed by blood pressure readings, self-reported doctor-diagnosed hypertension and antihypertensive drug intake. The results were adjusted for established confounders and in addition for PM2.5. Results: The adjusted odds ratio (95% confidence interval) for hypertension was 1.16 (1.01-1.35) per increase of the noise level by 10 dB(A). After additional adjustment for PM2.5 the effect estimate attenuated to 1.11 (0.95-1.30). For isolated systolic hypertension the effect estimates for noise were 1.48 (1.16-1.89) and 1.43 (1.10-1.86) after additional adjustment for PM2.5. Conclusion: Road traffic noise was associated with a higher prevalence of hypertension, particularly, systolic hypertension. The noise effect was only marginally affected by PM2.5, which may be due to different biological mechanisms