Exposure and Effect Indicators of Environmental Noise

Annoyance and sleep disturbance are generally accepted effects of environmental noise. Traffic noise is the most important source of noise induced annoyance. Long-term derogation of the recovery function of sleep by traffic noise has the potential to increase the sensitivity to daytime noise annoyance as well as the risk of cardiovascular and several other diseases. Noise induced arousal and secretion of cortisol especially in the first half of the night seem to be more sensitive indicators for noise induced detriment of sleep than remembered awakening reactions. The evidence of cardiovascular risk due to traffic noise is assessed as “limited or sufficient”. In most studies the daytime traffic noise level was related to the increase of cardiovascular risk. Nevertheless there is evidence that traffic noise exposure at night plays a more important role in the pathogenesis of noise stress induced increase of the cardiovascular risk than traffic noise exposure during the day. This was confirmed by the Spandau Health Survey, where a clear distinction was made between day time and night time traffic noise exposure. Among other diseases also chronic bronchitis and bronchial asthma were found to be related to traffic noise. These findings are in agreement with the results of study in children under combined exposure to traffic related noise and air pollution. The relative risks of chronic bronchitis, asthma and neurodermitis of the exposed children cannot be explained by air pollution alone. Therefore long-term traffic noise induced derogation of sleep must have had an adjuvant effect in the pathogenesis of these diseases. Finally noise induced hearing impairment due to military low altitude flight noise, impulsive noise from toy pistols etc., and long-term overexposure by loud music are summarised. Acoustic limiting values are proposed to avoid inner ear damage. To avoid traffic noise related health defects maximal indoor levels should be Lmax < 40 dB(A) or in the case of predominant low frequency noise Lmax < 60 dB(C).