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Introduction
‘Environmental Noise’ addresses all types of sound which potentially affects people in their homes, properties and in public areas. It has been defined by Directive 2002/49/EC (the Environmental Noise Directive, or END) as: “unwanted or harmful outdoor sound created by human activities, including noise emitted by means of transport, road traffic, rail traffic, air traffic, and from sites of industrial activity.”
In other jurisdictions different terminology is applied, such as ‘community noise’ and ‘neighbourhood noise’. Environmental noise, however, typically applies to the cumulative effect of noise emitted from many sources. Despite this, in some cases, we need to focus on the noise from an individual or specific source, such as in the investigation of noise complaints. Very often it is the characteristics and circumstances pertaining to the ‘specific source’ which mean that its impact upon a noise sensitive location (or receptor) far outweighs the contribution from other sources. In some situations the ‘noise emitter’ may be insensitive to his/her neighbours and might think that road traffic noise is more obvious than the noise from his/her chiller or air conditioning unit and that consequently, the complainant is unreasonable. Our tolerance to noise, however, is largely affected by a wide range of factors – one of which is the nature of the noise source. Often the likelihood of a noise to cause disturbance or complaint may be obvious, however, there are many cases that are not black and white. Typically a systematic and considered approach is required to assess environmental noise, particularly when there are noise complaints.
Dose-response relationships have been developed for different types of noise and these provide a numerical relationship between noise levels and the likely human response, or in other words, the percentage of respondents highly annoyed by a specified noise level. The results of listening tests, laboratory studies, social and noise surveys have evolved over decades and according to Wayant and Nykaza (2017): “Dose-response curves lie at the heart of most community noise laws and policies throughout the world.” These curves have been developed to facilitate a better understanding or estimation of the likely response of a population to particular sound levels. More recently, compelling evidence has been published that supports our understanding of the adverse effects of noise.
The fact that human reaction to noise is significantly influenced by the actual source of the noise is well illustrated in Table 1 using data from a 2010 European Environment Agency report. The table shows the percentage of highly annoyed persons related to threshold values of 45, 50, and 55 dB Lden. (Note: Lden is the day/evening/night noise index which is used to describe the annoyance caused by exposure to noise. Refer to tabulated formula and explanation).
Whereas many studies have highlighted our somewhat greater tolerance to railway noise than to traffic noise, European residents’ reactions to aircraft and wind-turbine noise are markedly less tolerant.
The European approach, however, to managing and regulating environmental noise has been subject to a strategic review.
The 2016 review reaffirms that the Environmental Noise Directive does not set any source-specific limit values at an EU level, although “establishing national limit values was viewed as being helpful by national Competent Authorities in many EU member states, since exceedance was often used as the basis for prioritising noise mitigation measures,” (European Commission, 2016). However, the authors reported that mandatory noise limit values have been set in 21 member states and non-binding targets in a further four. Nonetheless, there was limited evidence of their effective enforcement. So, this begs the question: are the authorities just paying lip-service to the environmental noise exposure ‘issue’ and is there real evidence that it should assume greater priority? The short answer is yes – to both questions.
World Health Organization
In a 2011 report, the World Health Organization (WHO) concluded that: “There is sufficient evidence from large-scale epidemiological studies linking the population’s exposure to environmental noise with adverse health effects. Therefore, environmental noise should be considered not only as a cause of nuisance, but also a concern for public health and environmental health.”
“are the authorities just paying lip-service to the environmental noise exposure ‘issue’ and is there real evidence that it should assume greater priority?”
The environmental burden of disease has been addressed by recent publications and controversial findings were published by the WHO in 2012. The WHO study incorporated a review of the scientific evidence supporting exposure–response relationships and case studies in calculating the burden of disease. The study methodology, based on exposure–response relationship, exposure distribution, background prevalence of disease and disability weights of the outcome, was applied to calculate the burden of disease in terms of disabilityadjusted life-years (DALYs). The results indicate that “at least one million healthy life years are lost every year from traffic related noise in the western part of Europe alone.”
The DALY was developed to enable policy makers to make rational choices for medical treatment and they are used to rank policy alternatives. Each clinical phenomenon is assessed to establish a weighting factor and the DALY is calculated as the sum of years of potential life lost due to premature mortality and the years of productive life lost due to disability. According to the protocol designed to assess these weights, the factor takes into account mortality, (loss of) mobility, self‑care, daily activities, pain/discomfort, anxiety/ depression and cognitive function.
The WHO has devoted significant priority to the burden of disease and their recently published guidelines (Environmental Noise Guidelines for the European Region, October 2018) provide recommendations for protecting human health from exposure to environmental noise. The 2018 guidelines provide robust public health advice and also serve as a solid basis for future updates, given the growing recognition of the problem and the rapid advances in research into the health impacts of noise.
“the 2018 guidelines provide robust public health advice and also serve as a solid basis for future updates, given the growing recognition of the problem”
The process of developing the 2018 guidelines has followed a rigorous methodology and the WHO recommendations are based on systematic reviews of evidence that consider more health outcomes of noise exposure than ever before. Importantly, they supersede the earlier WHO guidelines (1999 and 2009) and thus will have a profound effect on the manner in which environmental noise will be regulated throughout Europe and beyond. Before addressing some of their implications, it is worthwhile to briefly consider the pre-existing WHO guidelines.
In 1999 the WHO published guideline values for community noise in specific environments and LAeq was initially the preferred index.
To protect the majority of people from being seriously annoyed during the daytime, it was recommended that the sound pressure level on balconies, terraces and outdoor living areas should not exceed 55 dBA LAeq for a steady continuous noise (this LAeq was assessed over a 16-hour daytime and evening period). The 1999 WHO guidelines also stated:
‘For bedrooms the critical effect is sleep disturbance. Indoor guideline values for bedrooms are 30 dB LAeq for continuous noise and 45 dB LAmax for single sound events.…. At night-time, outside sound levels about one metre from facades of living spaces should not exceed 45 dB LAeq, so that people may sleep with bedroom windows open. This value was obtained by assuming that the noise reduction from outside to inside with the window open is 15 dB.’
Thus, the WHO (1999) indoor guideline value for bedrooms was 30 dBA (LAeq assessed over an eight-hour period), however, it was recognised by the WHO that lower noise levels had the potential to be disturbing, depending on the nature of the noise source.
In a major review, the WHO issued guidance in 2009 in recognition of the compelling evidence of adverse health effects from night-time exposure and recommended a Night Noise Guideline (NNG) of 40 Lnight dB outside a residential property. However, this was defined as a ‘long-term average sound level as opposed to a level measured during a limited period on one night. An interim target of 55 (Lnight, outside) was also set by the WHO in recognition of the very many situations in which the achievement of the NNG was not feasible.
So how have the 2018 Environmental Noise Guidelines for the European Region, changed and what are their implications? Firstly, specific recommendations have been formulated for road traffic noise, railway noise, aircraft noise, wind turbine noise and leisure noise. Secondly, their recommendations are rated as either strong or conditional. However, the guidelines do not explicitly consider industrial noise and indoor guideline values. Therefore any values not covered by the 2018 guidelines (such as industrial noise and shopping areas) should remain valid, i.e., the 2000 guidelines for the impact of industrial noise on residential property are still valid.
It is noted that ‘a strong recommendation can be adopted as policy in most situations. The guideline is based on the confidence that the desirable effects of adherence to the recommendation outweigh the undesirable consequences. The quality of evidence for a net benefit – combined with information about the values, preferences and resources – inform this recommendation, which should be implemented in most circumstances.’
On the other hand, a conditional recommendation requires a policymaking process with substantial debate and involvement of various stakeholders. There is less certainty of its efficacy owing to lower quality of evidence of a net benefit, opposing values and preferences of individuals and populations affected or the high resource implications of the recommendation, meaning there may be circumstances or settings in which it will not apply.
In conjunction with specific recommendations, several guiding principles were developed to provide generic advice and support for the incorporation of recommendations into a policy framework. They apply to the implementation of all the specific recommendations.
The guiding principles are stated as follows:
- Reduce exposure to noise, while conserving quiet areas
- Promote interventions to reduce exposure to noise and improve health
- Coordinate approaches to control noise sources and other environmental health risks
- Inform and involve communities potentially affected by a change in noise exposure
A summary of the recommendations for specific noise sources is outlined below.
Comparisons
The 2018 LLen recommendations can be compared with previous WHO Guidance – 55 dB LAeq for a steady continuous noise for ‘outdoor living areas’ to avoid serious annoyance (assessed over a 16-hour daytime and evening period, WHO 1999).
The 2018 Lnight recommendations can be compared with the 2009 guidance – 40 dB Lnight outside a residential property with an interim target of 55 (Lnight, outside), WHO 2009. The 2009 Lnight guidance and interim target applied to all sources.
Thus there are many differences in the current (2018) guidelines and while the 1999 guidelines defined environment-specific exposure levels (e.g. levels for outdoor living areas, inside bedrooms, schools, hospitals etc.) the current guidelines recommend values for outdoor exposure to road traffic, railway, aircraft and wind turbine noise.
With regards to ‘leisure noise, WHO estimated that 1.1 billion young people worldwide could be at risk of hearing loss due to unsafe listening practices. Furthermore, among young people aged 12 – 35 years in middle and high-income countries, ‘nearly 50% listen to unsafe levels of sound through personal audio devices (MP3 players, smartphones and others), and around 40% are exposed to potentially damaging levels of sound at nightclubs, bars and sporting events’. The emphasis on the 2018 leisure noise recommendations is on preventing hearing loss. Given that there is sufficient evidence that the nature of the noise ‘matters little in causing hearing loss’ so using the 1999 guidelines is a justified step to prevent permanent hearing loss. The 1999 guideline value for music through headphones/earphones was 85 LAeq, 1-hour and 110 LAF, max.
Conclusion
A range of factors (acoustic and non-acoustic) will affect the tolerance and or reaction of an individual to noise and the overall impact of a noise source. British Standard BS 4142 (2014) gives considerable emphasis to the degree by which the noise exceeds the pre-existing (or background) noise levels. Some of the other pertinent factors in assessing or predicting noise impacts include:
- The time, duration and predictability of the emission
- The amplitude and frequency of the noise emission
- The absolute sound pressure level of the noise source and variations over time
- Variations in the hearing sensitivity of individuals
- Site location, local land use, nature and character of the locality
- Activities underway when noise is audible
- Local attitudes to the source or sources of the noise
- The likely duration of the noise and the ability and/or willingness to control its impact
- The presence of special acoustic characteristics such as tones, impulsive elements or modulation (where the noise level changes in its loudness, tone or character)
- The incongruity or familiarity of the noise – is it typical of noise which would be normally heard in the area?
In practice, many social, psychological and economic factors will affect the sensitivity of an individual or a situation over time. In investigating complaints, a competent assessment should include a considered opinion as to whether a noise complaint is justified.
“there is likely to be widespread consultation regarding 2018 WHO guidelines and many may be slow to publicly adopt them”
It is noteworthy that there is likely to be widespread consultation regarding the 2018 WHO guidelines and many jurisdictions may be slow to publicly adopt or endorse them. Nonetheless, they are likely to have a marked effect on the framework in which environmental noise is regulated and controlled. The recommendations are more strictly based on the available scientific evidence, however, they might not lead to full protection of the population, including all vulnerable groups. The WHO Guideline Development Group stresses that the aim of the current guidelines is to define an exposure level at which effects certainly begin. It may take a long time for legal limits, standards and practices to fully adopt the guidelines but in the meantime, practitioners should ignore them at their peril.
