Noise is defined as unwanted sound. It is perceived as a form of pollution. Noise pollution can affect health, yet the effects are very difficult to quantify. It is believed that persistent exposure to noise, especially at night, may lead to psychological distress.

Some industrial workers in London are exposed to noise levels likely to cause deafness. Lower levels of noise due to aircraft and road traffic cause sleep disturbance and possibly hypertension. Hearing in younger people is likely to be damaged by current noise exposure in clubs. Noise reduction will be required in future by European Union regulation.

Noise may exceed WHO recommended levels in industrial processes (controlled by the Health and Safety Executive), domestic/leisure (usually short-term noise 'nuisance') and transport (aircraft, trains and road vehicles). The Health and Safety Executive estimate that there 1.3 million people are exposed to industrial noise levels above 85 dB(A) - perhaps 200 000 in London (RNID 1999). Levels of deafness actually caused are unknown. Aircraft and road noise causes annoyance, sleep disturbance and hypertension. 300 000 people live within the Heathrow annoyance 'noise contour' of 57 dB(A), but the actual disease impact is not known (Health Council of the Netherlands, 1999).

There are no estimates of the impact of road noise on health in London. It is likely that road traffic is the largest single cause of noise pollution in London (LPAC, 1994).Transport noise is associated with productivity losses caused by an inability to concentrate at work or disrupted sleep resulting in tiredness (Pearce, 1994).

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The problems linked to noise pollution form a significant part of the work of local Environmental Health Officers. Though noise nuisance may come from a variety of sources the majority are domestic. The type of information recorded locally may vary slightly but should include counts of the numbers of complaints and confirmed nuisances. National summaries are presented in the Reports of the Chartered Institute of Environmental Health Officers.

The London boroughs are the principle agencies for noise control. Most of their work is towards domestic noise. Private companies have responsibility for noise in industrial settings. They should have occupational health services, and the Health and Safety Executive (HSE) monitors and investigates when alerted, but it is likely that exposure to noise levels likely to cause future deafness exists. A new EU directive on noise has been established which will place responsibility on local authorities to reduce noise levels to EU standards. This will require the introduction of mapping of noise contours in large conurbations. This may have particular impact on transport noise - aircraft, railways and roads. Preliminary work has been done in Birmingham to test software that can produce noise maps, or more correctly Sound Immission Contour Maps (SICMs) and its has been found that it will be technically possible for local authorities to produce.

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Exposure to loud noise can cause permanent hearing damage. The important factors are the noise levels [given in decibel units dB(A)] and how long people are exposed to the noise, daily and over a number of years. The damage involves loss of hearing ability which is possibly made worse by permanent 'tinnitus' (ringing in the ears).

The Noise at Work Regulations 1989 came into effect on 1 January 1990 (the Noise at Work Regulations implement European Directive 86/188/EEC1). Various other regulations apply to noise or include specific provisions on it, including: the Management of Health and Safety at Work Regulations 1992 (as amended); the Provision and Use of Work Equipment Regulations 1992 and the Supply of Machinery (Safety) Regulations 1992.

Employers have a legal duty to protect the hearing of their employees. They have to reduce risk of damage to employees' hearing and take specific actions where the noise exposure of their employees is likely to be at or above any of three 'action levels'. Two of the action levels are values of 'daily personal noise exposure' expressed as L EP,d. These depend on the noise level in the working areas and how long people spend in them during the day. The first action level is an L EP,d of 85 dB(A) and the second action level is an L EP,d of 90 dB(A). There is also a peak action level of 200 pascals for the maximum pressure reached by the sound wave. The peak action level is most likely to be important where loud impulsive sources are used, such as cartridge operated tools.

Employers are required to take specific measures at these levels, including carrying out noise assessments reducing exposure providing information and training for employees issuing personal hearing protection.

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A guide to noise levels is:

• normal conversation 50 - 60 dB(A)
• a loud radio 65 - 75 dB(A)
• a busy street 78 - 85 dB(A)
• a heavy lorry about 7 metres away 95 - 100 dB(A)
• a pighouse at feeding time 110 dB(A)
• a chain saw 115 - 120 dB(A)
• a jet aircraft taking off 25 metres away 140 dB(A). (HSE, 2000)

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Intermittent, higher frequency, short duration, intensesounds have greater effects on health than do continuous, low frequency, long duration, low intensity sounds.

Annoyance is the most widespread problem caused by environmental noise. Annoyance reflects the way that noise affects daily activities. People's attitudes to noise and the environment in which they live can also determine annoyance. Quality of life may be worse if noise makes people feel angry or afraid. Noise is seen to be an avoidable harm.

Domestic noise, particularly noise from neighbours, is a major source of noise pollution. This can be especially difficult to cope with when it conveys information and meaning.

Sleep disturbance caused by environmental noise can affect the quality and quantity of sleep and lead to drowsiness, low mood and poor performance the following day.

Noise-related sleep disturbance is often caused by road traffic and neighbours. These noises are changeable and unpredictable. Aircraft noise does not appear to be a major cause of sleep disturbance.

Noise annoyance creates minor psychological problems (e.g. tension, irritability and difficulties concentrating). However it is likely that is noise causes serious mental health problems.

Noise is known to cause sleep disturbance. Little data exists on this subject but the National Noise attitude Survey gives an indication of the proportion of people who are affected by noise at night times.

Recently the Department of Health has commissioned several projects on noise and health issues.

Researchers at MRC Institute for Hearing Research suggest that the causes of environmental deafness amongst people is not distinguishable. They suggest that 16% of 18 to 85 year olds have a hearing problem, and that this is a major preventable factor in adults - predominantly from occupational noise. In younger people noise from discos, clubs and pubs play a more significant role than from industrial sources.

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Date	Title	Format	View
2 Dec 2003	Noise Complaints per Million People, 1991/1992 - 1999/2000, London
2 Dec 2003	Noise monitoring and control, 1998/99 - 1999/00, London
2 Dec 2003	Percentage of people reporting noise disturbance, 1991, London

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