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|Year : 2010 | Volume
| Issue : 47 | Page : 61--63
Summary of night noise guidelines for Europe
Rokho Kim1, Martin van den Berg2,
1 World Health Organization (WHO), European Centre for Environment and Health, Regional Office for Europe, Bonn, Germany
2 Ministry of Housing, Spatial Planning and the Environment (Ministry VROM), The Hague, The Netherlands
European Centre for Environment and Health, World Health Organization, Regional Office for Europe, Bonn
Considering the scientific evidence on the threshold of night noise exposure indicated by L night as defined in the Environmental Noise Directive (2002/49/EC), L night value of 40 dB should be the target of the night noise guideline (NNG) to protect the public, including the most vulnerable groups such as children, the chronically ill and the elderly. L night value of 55 dB is recommended as an interim target for countries which cannot follow NNG in the short term for various reasons and where policy-makers choose to adopt a stepwise approach. These guidelines may be considered an extension to the previous World Health Organization (WHO) guidelines for community noise (1999).
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Kim R, Berg M. Summary of night noise guidelines for Europe.Noise Health 2010;12:61-63
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Kim R, Berg M. Summary of night noise guidelines for Europe. Noise Health [serial online] 2010 [cited 2020 Aug 14 ];12:61-63
Available from: http://www.noiseandhealth.org/text.asp?2010/12/47/61/63204
In October 2009,  the World Health Organization (WHO) Regional Office for Europe published night noise guidelines for Europe (NNGL) to provide evidence-based policy advice to the Member States in the development of future legislation and policy action in the area of control and surveillance of night noise exposure. NNGL complements the previous WHO guidelines for community noise (1999), reflecting the advancement of research. This paper summarizes the key recommendations of NNGL. The need for the WHO Regional Office for Europe/Europe to develop "health-based" guidelines originated in part from the European Union (EU) Directive 2002/49/EC relating to the assessment and management of environmental noise (commonly known as the Environmental Noise Directive, END), which compels EU Member States to produce noise maps and action plans to protect the public from harmful level of environmental noise. The WHO's work in the development of NNGL was partially supported by a grant from the European Commission and contributions from the Swiss and German governments.
Process of Developing Guidelines
In 2003, the WHO Regional Office for Europe European Centre for Environment and Health, Bonn, Germany, set up a working group of experts. The review of available scientific evidence on the health effects of night noise was carried out by an interdisciplinary team to formulate health-based guidelines. The contributions from the experts were integrated into draft reports following discussion at four technical meetings of the working group. In 2006, all the draft reports were compiled into a draft document on guidelines for exposure to noise at night, which was reviewed and commented on by a number of stakeholders and experts. At the final conference in Bonn on 14 December 2006, representatives from the working group and stakeholders from industry, government and nongovernmental organizations reviewed the contents of the draft document and reached a general agreement on the guideline values of NNGL.
Long-term effects such as cardiovascular disorders have to be described by indicators summarizing the acoustic situation over a long time period such as annual average of night noise level outside at the faηade (e.g., L night defined by END), while instantaneous effects such as EEG- or awakening reactions are better correlated with the (maximum) level per event (L Amax or SEL), such as the passage of a lorry, airplane or train. NNGL adopted a long-term exposure indicator, L night , in formulating the health-based guideline values because chronic health effects over a longer period of time are a more serious burden than acute effects, from the public health point of view. Also, it was clear that in the coming years in Europe, L night data would become widely available and could be used by the local and central governments preparing action plans following the mandates of END. The experts of the working group, however, acknowledged that among the currently used indicators for regulatory purposes, L Aeq (A-weighted equivalent sound pressure level) over a single night and L Amax are useful to predict short-term or instantaneous effects.
Noise, Sleep and Health
There is plenty of evidence that sleep is a biological necessity, and disturbed sleep is associated with a number of health problems. Studies on sleep disturbance in children and in shift workers clearly show the adverse effects such as increased accidents on the following day. Noise disturbs sleep by a number of direct and indirect pathways. Even at very low levels, physiological reactions (increase in heart rate, body movements and arousals) can be reliably measured. Also, it was shown that awakening reactions are relatively rare, occurring at a much higher level than the physiological reactions.
Children have a higher awakening threshold than adults and therefore are often seen to be less sensitive to night noise. For other effects, however, children seem to be equally or more reactive than adults. As children also spend more time in bed they are exposed more to night noise levels. For these reasons, children are considered a risk group. Since the sleep structure becomes more fragmented with ageing, elderly people are more vulnerable to disturbance. This also happens in pregnant women and people with chronic illnesses, so they too are a group at risk. Finally, shift workers are at risk because their sleep structure is under stress due to the adaptations of their circadian rhythm and because they have to sleep at times where noise levels are generally higher
Recommendations for Health Protection
Based on the systematic review of evidence produced by epidemiological and experimental studies, the relationship between night noise exposure and health effects can be summarized as below [Table 1].
Below the level of 30 dB L night , no effects on sleep are observed except for a slight increase in the frequency of body movements during sleep due to night noise. There is no sufficient evidence that the biological effects observed at the level below 40 dB L night are harmful to health. However, adverse health effects are observed at the level above 40 dB L night , such as self-reported sleep disturbance, environmental insomnia, and increased use of sleeping pills and sedatives.Therefore, 40 dB L night is equivalent to the lowest observed adverse effect level (LOAEL) for night noise. Above 55 dB, cardiovascular effects become the major public health concern, which are likely to be less dependent on the nature of the noise. Closer examination of the precise impact will be necessary in the range between 40 dB and 55 dB as much will depend on the detailed circumstances of each case. In conclusion, the night noise guideline values were recommended for the protection of public health from night noise as below [Table 2].
For the primary prevention of subclinical adverse health effects related to night noise in the population, it is recommended that the population should not be exposed to night noise levels greater than 40 dB of L night during the part of the night when most people are in bed. The LOAEL of night noise, 40 dB L night , can be considered a health-based limit value of the night noise guidelines (NNG) necessary to protect the public, including most of the vulnerable groups such as children, the chronically ill and the elderly, from the adverse health effects of night noise. An interim target (IT) of 55 dB L night is recommended in the situations where the achievement of NNG is not feasible in the short run for various reasons. It should be emphasized that IT is not a health-based limit value by itself. Vulnerable groups cannot be protected sufficiently at this level. Therefore, IT should be considered only as a feasibility-based intermediate target which can be temporarily considered by policy-makers for exceptional local situations. The most recent data from the European Environment Agency show that around 20% of the population in the major cities and around major infrastructure of most EU member states is exposed to levels over 55 L night . It should be underscored that special attention should be paid to the different meanings of different indicators when NNGL is compared to other guidelines. For instance, the real situations respectively represented by L night =40 dB and L Aeq,8h =40 dB can be totally different, depending on the intermittent or continuous nature of the noise events. The former is one-year average sound level outside on the most exposed faηade, while the latter is the average sound level over a single period of eight hours usually measured in the room.
Relation with the Guidelines for Community Noise (1999)
Impact of night-time exposure to noise and sleep disturbance was indeed covered in the 1999 guidelines, as below: 
"If negative effects on sleep are to be avoided the equivalent sound pressure level should not exceed 30 dBA indoors for continuous noise. If the noise is not continuous, sleep disturbance correlates best with L Amax and effects have been observed at 45 dB or less. This is particularly true if the background level is low. Noise events exceeding 45 dBA should therefore be limited if possible. For sensitive people an even lower limit would be preferred. It should be noted that it should be possible to sleep with a bedroom window slightly open (a reduction from outside to inside of 15 dB). To prevent sleep disturbances, one should thus consider the equivalent sound pressure level and the number and level of sound events. Mitigation targeted to the first part of the night is believed to be effective for the ability to fall asleep."
The 1999 guidelines are based on studies carried out up to 1995 (and a few meta-analyses some years later). NNGL considered important new studies which provided new insights into normal and disturbed sleep. New information has made more precise assessment of exposure-effect relationship possible. The thresholds are now known to be lower than L Amax of 45 dB for a number of effects: EEG-arousals and body movements can be demonstrated down to levels of L Amax = 32 dB (A).
The recommendations of the 1999 guidelines still stand: there are good health-based reasons for people to sleep with their windows open; and to prevent sleep disturbances one should consider the equivalent sound pressure level and the number of sound events. The present guidelines encourage responsible authorities and stakeholders to do this. Viewed in this way, the NNGL is complementary to, as well as an update of the 1999 guidelines. This means that the recommendations on government policy framework on noise management elaborated in the 1999 guidelines should be considered valid and relevant for the WHO Member States to achieve the guideline values of this document.
Even though NNGL was developed by the WHO Regional Office for Europe/Europe focusing on the situation of and to be applicable to the Member States of the European Region, the evidence base and recommendations in the document should be relevant to any local or central governments dealing with night noise issues. However, a proper caution should be given to the interpretation of noise indicators as mentioned above.
L night is the night-time noise indicator L night of Directive 2002/49/EC of 25 June 2002: the A-weighted long-term average sound level as defined in ISO 1996-2: 1987, determined over all the night periods of a year; in which: the night is a minimum of eight hours (the default is 23.00 - 07.00 local time, but Member States may adapt this to the sleep pattern of the population), a year is a relevant year as regards the emission of sound and an average year as regards the meteorological circumstances, the incident sound is considered, the assessment point is the same as for L den , outside on the most exposed facade. See Official Journal of the European Communities, 18.7.2002, for more details.
|1||WHO Regional Office for Europe, Night noise guidelines for Europe, Copenhagen. Available from: http://www.euro.who.int/document/e92845.pdf. [last cited on 2009].|
|2||WHO, Guidelines for community noise, Geneva. Available from: http://www.who.int/docstore/peh/noise/guidelines2.html. [last cited on 1999].|