Traffic noise and hypertension: an epidemiological study on the role of subjective reactions.

Traffic noise is discussed as a possible risk factor for hypertension. However, no data are available concerning the moderating effect of the subjective reactions and the noise attitudes. In the present epidemiological study the relationship between these subjective factors and blood pressure was investigated separately for the inhabitants of two residential areas. One area had high traffic volumes, resulting in a high sound level (Leq greater than 73 db (A), noisy area); the other was socially comparable but with an essentially low sound level (Leq less than 51 db (A), control area). The relationship between the subjective reactions and blood pressure was checked by analyzing the incidence of treatment for hypertension (n = 919) and by analyzing the change of casual blood pressure after living 2.25 years in the respective residential area in a subgroup of those who had been normotensive (n = 36). The results obtained by either of these approaches indicate that the subjective factors do not modify the risk of hypertension in noisy areas, whereas they seem to be relevant for medium size stimuli. It is concluded that one can physiologically cope with low stimuli, but this is impossible for extreme stimuli. The results suggest also that the subjective reaction to extreme stimuli is strongly biased by attitudes which cannot be related to blood pressure. The family history of hypertension was found to be independent of the subjective reactions to noise.