The handbook of the effects of environmental noise on health

Marja Heinonen-Guzejev

”The handbook of the effects of environmental noise on health” deals with noise in accordance with the WHO recommendation of the classification of diseases, impairments and disabilities due to various external and internal causes: disease include organ or cellular lesion, e.g. inner ear lesions;
impairment is a measurable change of function such as blood pressure;
disability is an experienced functional effect, e.g. annoyance; as an example of handicap as an effect of environmental noise for an individual, can be morbidity and working ability and for the society the need of health services.

Noise has many negative effects on human health, well-being and comfort. The same sound may affect different people in different ways, but on the level of population, the harmful effects of noise have been proved without doubt. Noise impairs the quality and comfort of the living environment: for example a noisy environment limits the opportunities for keeping windows open and for spending time out of doors.

The handbook stresses the various noise effects rather than taking a conventional approach and starting with the acoustic features of noise, such as loudness. Different effects of environmental noise are discussed in the order of their frequency and significance. Annoyance, which is the most widespread, is followed by physiological effects, such as effects on sleep, cognitive performance, especially in children, speech communication, cardiovascular functions, and finally by hearing impairment, which does not occur so frequently.

Annoyance is defined as a feeling of discomfort, which is related to adverse influencing of an individual or a group by any substances or circumstances. It is as a multifaceted psychological concept, covering immediate behavioural noise effects aspects, like disturbance and interfering with intended activities, and evaluative aspects like “nuisance”, “disturbance”, “unpleasantness”, and “getting on one's nerves”. Exposure-effect relationships have been derived for exposure to the three main types of traffic noise: road traffic, railway, and aircraft noise. Aircraft noise is statistically significantly more annoying and railway noise is less annoying than road traffic noise.

The primary noise effects on sleep are difficulties in falling asleep; alterations of sleep stages or depth, especially a reduction in the proportion of REM-sleep; awakenings; increase in body movements; increased blood pressure; increased heart rate; vasoconstriction; changes in respiration; and cardiac arrhythmia. Exposure to night-time noise also induces secondary effects, that can be measured the day following the night-time exposure, while the individual is awake. They include reduced perceived sleep quality;
increased fatigue; depressed mood or well-being; and decreased performance. Various studies have also shown that people living in areas exposed to night-time noise have an increased use of sedatives or sleeping pills. Other
frequently reported behavioral effects of night-time noise include closed bedroom windows and use of personal hearing protection.

Noise affects communication by impairing the ability to distinguish speech sounds and signals in a noisy environment. In addition, straining the voice when speaking in noisy environment may damage the vocal cords. Noise can cause harmful cognitive impacts to perception, thought and memory functions. In children chronic aircraft noise exposure has been associated with poorer reading comprehension, limitations in learning ability and sustained attention. Noise effects impair the performance and functional capacity of those exposed to it and may be one reason explaining the marginalization of individuals.

Noise can be seen as an environmental stressor challenging cardiovascular and metabolic homeostasis. Acute noise exposure activates the autonomic nervous system and endocrine system, which leads to temporary changes such as increased heart rate, vasoconstriction and increased blood pressure. The sympathetic-adrenal-medullary (SAM) system and the hypothalamic-pituitary-adrenal (HPA) system are the two major stress systems that seem to play an important role in influencing cardiovascular and metabolic functions. Sustained activation of the SAM-system with overexposure to adrenaline and noradrenaline can contribute to the development of
cardiovascular disease. Chronic noise exposure influencing the HPA-axis is associated with metabolic changes, which can also increase the risk of cardiovascular disease.

Epidemiological studies have suggested a higher risk of cardiovascular disease, including high blood pressure and myocardial infarction, in subjects who were chronically exposed to high levels of transportation noise. In a meta-analysis of 61 epidemiological noise studies for noise categories above 60 dB(A) a higher ischaemic heart disease risk was relatively consistently found, but the statistical significance was rarely achieved. An increase in risk of myocardial infarction was found with increasing noise levels above 60 dB(A) showing a dose-response relationship (Babisch 2006, 2008). A significant association of aircraft noise and hypertension has been shown in a meta-analysis of 43 epidemiological studies (van Kempen 2002).

Hearing impairment is typically defined as an increase in the threshold of hearing and it is assessed by threshold audiometry. Worldwide, noise-induced hearing impairment is the most prevalent irreversible occupational hazard. In the developing countries, not only occupational noise, but also environmental noise is an increasing risk factor for hearing impairment.

The handbook stresses individual noise sensitivity, which has not been ufficiently recognized earlier. Noise sensitive individuals are more affected by noise than less sensitive individuals. They pay more readily attention to noise, perceive more threat from noise and may react more to noise than less ensitive individuals. Noise sensitivity is a predictor of annoyance. It is a factor modifying or mediating the effects of noise exposure on the outcome measure, and it may be directly related to outcomes such as health status. In a Finnish study, cardiovascular mortality was significantly increased among noise ensitive women. In women the interaction of noise sensitivity and lifetime noise exposure was statistically significant for coronary heart mortality. Among men no statistically significant effects were found. However, in the ssociation of lifetime noise exposure with cardiovascular mortality there were no significant differences between men and women (Heinonen-Guzejev et al. 2007).

The handbook also includes an appendix with WHO guidelines for environmental noise. The available knowledge of the adverse effects of noise on health is sufficient to propose guideline values for community noise for the following noise effects: annoyance, speech intelligibility and communication nterference, disturbance of information extraction, sleep disturbance and hearing impairment.