Traffic noise and cardiovascular risk. The Caerphilly study, first phase. Outdoor noise levels and risk factors.

As part of the Caerphilly study, traffic noise exposure and risk for ischemic heart disease (IHD) were studied in a sample of 2,512 men aged 45-59 yr. The traffic noise emission level ranged between Leq = 51-70 dB(A) (6-22 hr, 10 min). No association was found between traffic noise and prevalence of IHD. Associations were found between noise and potential IHD risk factors including systolic blood pressure, oestradiol, total cholesterol, plasma viscosity, antithrombin III (increases), cortisol, and platelet count (decrease). Not all results supported the hypothesis that traffic noise increases the risk for IHD. The possibility of confounding cannot be excluded, although an extensive range of potential confounding variables were included in the analysis.