Noise-induced annoyance and morbidity results from the pan-European LARES study.

Traffic noise (road noise, railway noise, aircraft noise, noise of parking cars), is the most dominant source of annoyance in the living environment of many European countries. This is followed by neighbourhood noise (neighbouring apartments, staircase and noise within the apartment). The subjective experience of noise stress can, through central nervous processes, lead to an inadequate neuro-endocrine reaction and finally lead to regulatory diseases. Within the context of the LARES-survey (Large Analysis and Review of European housing and health Status), noise annoyance in the housing environment was collected and evaluated in connection with medically diagnosed illnesses. Adults who indicated chronically severe annoyance by neighbourhood noise were found to have an increased health risk for the cardiovascular system and the movement apparatus, as well as an increased risk of depression and migraine. Furthermore adults with chronically strong annoyance by traffic noise additionally showed an increased risk for respiratory health problems. With regards to older people both neighbourhood and traffic noise indicated in general a lower risk of noise annoyance induced illness than in adults. It can be assumed that the effect of noise-induced annoyance in older people is concealed by physical consequences of age (with a strong increase of illnesses). With children the effects of noise-induced annoyance from traffic, as well as neighbourhood noise, are evident in the respiratory system. The increased risk of illness in the respiratory system in children does not seem to be caused primarily by air pollutants, but rather, as the results for neighbourhood noise demonstrate, by emotional stress.

Nocturnal awakenings due to aircraft noise. Do wake-up reactions begin at sound level 60 dB(A)?

Night-time wake-up thresholds at noise levels of 60 dB(A) are frequently employed in Germany to establish "noise polluted areas". The criterion is, however, based on an incorrect processing of statistical data gathered from an evaluation of literature performed by Griefahn et al. (1976). This finding has emerged from an extensive revision of the study. Using appropriate statistical methods, maximum levels of under 48 dB(A) are assessed as waking-up thresholds at ear level in sleeping persons, in contrast to maximum levels of 60 dB(A) calculated by Griefahn et al. in 1976. The linear dose-response relationship, which in the course of the revision could be derived from the early publications, agrees with the results of more recent literature evaluations. The present contribution is not intended to give rise to the question whether in the interest of medical prevention it is reasonable to develop night-time protective policies merely founded on noise levels marking the "statistical" onset of nocturnal wake-up reactions. In this context, emphasis is laid on the deformation of the biological rhythm of sleep.

Stress hormones and sleep disturbances - electrophysiological and hormonal aspects.

In noise effect research often the awakening reaction is maintained to be the only important health related reaction. The main argument is that sleep represents a trophotropic phase ("energy storing"). In contrast to this awakening reactions or lying awake belong to the ergotropic phase ("energy consuming"). Frequent or long awakening reactions endanger therefore the necessary recovery in sleep and, in the long-run, health. Findings derived from arousal and stress hormone research make possible a new access to the noise induced nightly health risk. An arousal is a short change in sleeping condition, raising the organism from a lower level of excitation to a higher one. Arousals have the function to prevent life-threatening influences or events through activation of compensation mechanisms. Frequent occurrences of arousal triggered by nocturnal noise leads to a deformation of the circadian rhythm. Additionally, the deep sleep phases in the first part of the night are normally associated with a minimum of cortisol and a maximum of growth hormone concentrations. These circadian rhythms of sleep and neuroendocrine regulation are necessary for the physical as well as for the psychic recovery of the sleeper. Noise exposure during sleep which causes frequent arousal leads to decreased performance capacity, drowsiness and tiredness during the day. Long-term disturbances of the described circadian rhythms have a deteriorating effect on health, even when noise induced awakenings are avoided.