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Although environmental noise causes annoyance, there is little evidence from studies of psychological symptoms, psychotropic drug use, mental hospital admissions, and community studies that it causes psychiatric disorder. 1 Exposure to aircraft noise was not associated with psychiatric disorder in a cross sectional survey in west London, 2 but the population exposed to noise may have been biased by prolonged noise exposure and may represent "survivors" of noise, the most vulnerable to noise having moved away or never having moved into the noisy area. The relation between traffic noise at baseline and psychiatric disorder at follow up is explored in the Caerphilly collaborative heart disease study, a population unlikely to have been selected by noise exposure.
Subjects, methods, and results
In the second phase of the Caerphilly study all men aged 50-64 years living in Caerphilly, south Wales, were invited to attend a screening clinic. 3 Follow up was carried out five years later. Street measurement of A-weighted sound pressure level (dB(A)) was used to derive traffic noise maps, and subjects were grouped into five-decibel categories of traffic noise emission level, in terms of the average sound pressure (Leq) from 6 am to 10 pm. 4
The 30 item general health questionnaire was used to establish the presence of psychiatric disorder; it was validated against psychiatric interview in a subsample and a case threshold of 4/5 was established. 5 Depression and anxiety subscales were extracted from the general health questionnaire.
The association between noise exposure...