[Environmental medical action required on exposure to noise]

Basing on request for an expertise on the medical effects of noise on healthy adults, permissible values for mainly traffic noise were estimated from the literature. If the permissible values are exceeded, preventive medical action is necessary. Below these values the probability of noise-induced health hazards is essentially zero. The authors presume that noise levels above these permissible values, but below the limit of bearability, are an increasing danger to health. Preventive medical action must be weighed against the risk involved in persistent noise, depending on the situation and the need protection. The effect of noise as a health hazard is, apart from the mechanical damage to the inner ear, a psycho-physiological deregulation which can be either indirectly due to the annoyance or directly caused by stress of the vegetative-hormonal system. Therefore different permissible values for annoyance, the stress on the vegetative-hormonal system and for the loss of hearing are suggested, for both continual and maximum noise levels. In addition, de-regulation depends on the time of acoustic exposure because the sensitivity to noise follows a 24-hour cycle (circadian rhythm). It is therefore necessary to determine personal permissible limits for the nocturnal noise (sleep disorder). Permissible values for children are also suggested.