Noise pollution

In document New Horizons (Page 110-114)

This section is authored by Stephen Stansfield, Professor of Psychiatry, Wolfson Institute of Preventive Medicine, Queen Mary University of London

Background

The most frequent human responses to environmental noise are annoyance and sleep disturbance. Annoyance, which includes mild anger and feelings of intrusion of privacy, is also a response to disturbance of activities by noise. The level of

annoyance to noise is influenced by many other factors including sensitivity to noise, fear of the noise source, and feelings that the noise producers are taking insufficient care. Annoyance to environmental noise increased in the UK between 2000 and 2012 despite little increase in exposure, suggesting that tolerance of environmental noise has decreased.1 Noise exposure during sleep induces arousals, delays sleep onset, reduces slow-wave and REM sleep and increases the length of time spent awake.2 Short-term effects of noise on sleep include impaired mood, increased daytime sleepiness, and impaired cognitive performance. Generally noise exposure in health studies is measured as the average sound pressure over a specific period using decibels as the unit (dBA is the unit of A-weighted sound pressure level in decibels) weighted according to differences in human hearing sensitivity at different frequencies.

The extent of noise pollution

In 2012, 83% of a survey sample in the UK reported they heard road traffic noise, 72% aircraft noise and 48% noise from building, construction and road works at home in the last 12 months.2 Forty eight per cent reported that their home life was ‘spoiled to some extent’ by environmental noise. Road traffic noise is the most prevalent form of environmental noise exposure. 125 million people across Europe are exposed to noise levels above 55dBLden, a level at which human health effects are thought to become evident.3 Although cars and planes have become quieter than in the past there are now many more of them.

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The health effects of noise pollution

In general, acute responses to noise, defined as unwanted sound, include startle responses and physiological arousal. In the longer term, repeated exposure and arousal may lead to more serious health effects which may be part of the body’s response to chronic stress. In recent years studies have shown that environmental noise exposure has been associated with a range of health outcomes (Basner et al, 2014). The mechanism of noise effects on health is thought to be via the stress hypothesis where prolonged noise exposure increases physiological arousal and the secretion of stress hormones such as adrenaline, noradrenaline and cortisol. This causes raised blood pressure and heart rate, raised blood sugar and blood lipids and may lead to arterial endothelial dysfunction.4

There is convincing evidence that road traffic noise is linked to increased risk of hypertension (meta-analysis of 24 studies between 1970 and 2010, OR=1.034 95%CI 1.01,1.06 per 5 dB increase in 16hr average road traffic noise level).5 There is also a small but consistent risk of coronary heart disease related to road traffic noise (OR=1.08 95%CI 1.04,1.13 per 10dB Ldn increase in road traffic noise).6 In ecological studies aircraft noise has been associated with increased cardiovascular disease risk and hospital admissions.7 Aircraft and road traffic noise exposure have also been associated with increased risk of stroke8.9, diabetes mellitus10 and even mortality.11,12 Some variation in the magnitude of these associations may be related to noise exposure misclassification and noise levels at residences are only an approximation of noise exposure across the day. One suggestion has been that effects of noise might be explained by concurrent air pollution exposure but Tétrault (2013)13 found that the point estimates of the association between road traffic noise and cardiovascular disease changed less than 10% after adjustment for air pollution. Environmental noise exposure is also related to range of other effects. In children aircraft noise exposure has been linked to delays in children’s reading on standard scales in cross-national studies.14,15,16 Prenatal exposure to modelled road traffic noise has been related to low birth weight in a large Canadian study, adjusting for the effects of air pollution.17 However, two contemporary reviews have found no consistent association between environmental noise and prematurity and low birth weight but the studies examined were very heterogeneous.18,19

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Noise pollution and the burden of ill health

In order to assess the magnitude of the effects of environmental noise exposure on health the WHO published the burden of disease from environmental noise in Europe, based on noise exposure, the distribution of exposure and existing

exposure-response relationships. 61,000 DALYs were attributed to ischaemic heart disease based on hypertension and IHD outcomes, 45,000 DALYs to cognitive impairment in children and young people, aged 7-19 years, 903,000 DALYs to sleep disturbance, 22,000 DALYs to tinnitus, and 654,000 DALYs for annoyance.20

In terms of the health effects of environmental pollution in Europe, environmental noise comes second in burden of disease to air pollution and arguably is responsible for more disturbance of quality of life. Environmental noise is also responsible for more life years lost than other significant environmental pollutants such as lead, ozone and dioxins.21

What can be done to reduce noise exposure and consequent health effects? Interventions to reduce population noise exposure can be considered at several steps along the pathway from the noise source to the receiver.22 Reduction of noise at source is an ideal but often expensive solution such as designing quieter cars and aircraft and the provision of sound absorbing tarmac to reduce tyre noise or grinding rail tracks to reduce noise. More easily achievable source reductions include airport night curfews, changes in numbers of flights from airports and changes in traffic flows on motorways. Interventions between the source and the receiver, such as sound insulation of windows or noise barriers along roads and railways have been shown to be effective in reducing levels of noise exposure.23 New/closed

infrastructure interventions include closure of flight paths, introduction of bypasses and urban planning control such as the avoidance of new buildings, especially sensitive buildings such as schools, close to noise sources. Other physical interventions include the availability of a quiet side to dwellings exposed to road traffic noise which has been shown to reduce annoyance and the availability of green space for psychological restoration.24 Education/communication interventions help to educate people to change behaviour to reduce noise exposure or to explain the reasons for noise changes which may help to reduce community annoyance levels.

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At the level of public policy the European Noise Directive requires EU states to map noise levels in urban agglomerations and develop action plans to reduce noise levels in the highest exposed areas.3 This has focused attention on noise as an issue, with increasing effort to standardise data collection across countries, but there is still incomplete data from many areas. In England, the Noise Policy Statement for

England***** sets out the long-term vision of government noise policy to promote good health and a good quality of life through management of noise. Its aims are to avoid significant adverse impacts on health and quality of life, mitigate and minimise adverse effects and where possible contribute to the improvement of health and quality of life.

*****

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In document New Horizons (Page 110-114)