Characterization of road traffic noise exposure and prevalence of hypertension in central Taiwan.

Epidemiological studies have demonstrated that road traffic noise exposure is associated with hypertension in European, but the associations related to traffic sources and in other population are unclear. This study investigated the association between road traffic noise exposure and the prevalence of diagnosed hypertension among 321 male and 499 female resided near main roads in Taichung, Taiwan. Road traffic noise levels and traffic flow rates were measured simultaneously during 0900-1700 on weekdays in 2008. Multivariate logistic regressions were applied to estimate odds ratios (ORs) for hypertension by adjusting for potential confounders. Road traffic noise levels were significantly associated with traffic flow rates of motorcycles, light-duty gasoline vehicles, light-duty diesel trucks and heavy-duty diesel trucks and had the highest correlation with motorcycles. Per one unit (vehicle per hour) increase in the log-transformed traffic flow rate of motorcycles was significantly related to the increment of 7.20±1.40 A-weighted decibels (dBA) in the traffic noise exposure. The high-exposure group (82.2±1.7dBA, n=358) had the significantly higher prevalence of hypertension (adjusted OR=2.15, 95% CI=1.08-4.26) than the low-exposure group (77.2±1.6dBA, n=462). There was an increasing trend (p=0.023) between the prevalence of hypertension and residents exposed to <77dBA, 77-80dBA, 80-83dBA and ≥83dBA, respectively. Such an association was pronounced after adjusting for the total traffic flow rate. The study findings suggest that road traffic noise exposure may be associated with hypertension and the dominant source of traffic noise is motorcycles in central Taiwan.