Noise pollution is among the most common complaints regarding environmental issues in Europe, especially in densely populated and residential areas near major roads, railways and airports. But noise - unwanted sound - is more than a mere annoyance, even at levels below ear damaging volumes. It disturbs sleep, affects cognitive functions in children, causes physiological stress reactions and can lead to cardiovascular health problems, including artery disease (atherosclerosis), high blood pressure and heart disease, for those exposed to it on a repeated, long-term basis.
The EU's Environmental Noise Directive (END) has initiated action plans in Member States to reduce environmental noise exposure and its effects. This Thematic Issue reports on recent research to help guide effective noise action plans throughout Europe.
An important first step in noise management is to measure its effects on wellbeing and health. Medical tests suggest that noise affects the nervous and hormonal systems, which in turn disrupts the stability of the healthy human organism. Transferring these effects to the wider community, the article 'Traffic noise causes loss of over one million healthy life years in western Europe' describes the World Health Organization's (WHO) quantitative tool for assessing noise-related health impacts which will help set priorities for local and global noise mitigation measures. This has estimated that the health impact of environmental noise in western Europe could be up to 1.6 million healthy life years lost annually through ill health, disability or early death.
Adverse effects occur, in particular, when noise interferes with activities such as communication, concentration and sleep. Cognitive performance in children is reduced at even relatively low environmental noise levels around schools. Researchers have analysed European data on this, as described in 'Cognitive impairment caused by aircraft noise: school versus home', and concluded that exposure to aircraft noise during the day has a greater impact than sleep-disruption caused by exposure to aircraft noise during the night. Both are damaging, but protective policy could therefore be more effective if focused at the school level.
Noise maps drawn up according to the END can be used to assess public exposure to noise, an important step in developing appropriate action plans at a local scale. Researchers in Ireland have developed a method for this, explained in 'Noise maps suggest too many people exposed to damaging noise levels', and estimated the reduction levels of exposure to high noise levels if measures such as reduced speed limits and noise barriers are introduced.
Annoyance is a major outcome of noise exposure. Public surveys provide some indication that aircraft noise is increasingly negatively judged by the population. However, it has been suggested that these survey results could be partly caused by changes in survey methods and participants. Recent research explores this possibility, but concludes that methodological issues are not the reason behind increased reported annoyance levels. See: 'Is the public really becoming more annoyed by aircraft noise?'.
Noise from transportation is by far the most widespread source of noise exposure, causing most annoyance and public health concerns. A number of articles in this issue refer to noise mitigation measures. Quiet road surfaces should increasingly be used in areas of high traffic and have great potential to reduce noise emissions. Their durability can be improved when using dense surfaces instead of thin layer surfaces. 'Quiet road surfaces may have financial as well as acoustic benefits' explores how to balance the impacts, both positive and negative, of quieter road surface materials.
Traffic management (reduction of heavy vehicles and speed reduction) is a cost-effective measure of reducing noise. New research in Spain has explored solutions to reducing traffic noise, and found that combining global measures, such as speed restrictions, and local measures, such as noise screens, provides a strong solution. See: 'Combined traffic management and physical measures reduce noise effectively' for more details.
These articles provide just a glimpse into environmental noise research, and much further investigation is needed to help guide policy in the future. For example, the combined effects of noise exposure and other environmental stressors are as yet unexplored and there is a need to update annoyance responses to aircraft noise in view of recent trends. Furthermore, studies are needed to quantify the impact of emerging noise sources, such as high speed rail and wind turbine noise.
The effects of healthy sound environments should not be overlooked - quiet and restorative soundscapes can contribute to human wellbeing and deserve increased research and policy attention.
Existing techniques for measuring noise and assessing its impacts have some limitations, which means that current research cannot answer all policy questions. Research into noise and mental health in adults are compromised by poor study design and long-term studies using standardised clinical interviews to assess mental health diagnoses (affective and anxiety disorders), measuring exposure to other environmental and social stressors would be an advance in this area of research.
The use of Geographic Information Systems techniques has been an important technical advance in measuring environmental noise across large areas. However, their coverage of the road network is often incomplete, the grid size and the quality of the input data across countries may sometimes not be comparable, among other limitations. This situation may be improved after the second round of noise mapping according to the Environmental Noise Directive. The emphasis on energy averaged noise measures accounts for the number of events and the maximum noise level of a single event. However, although vehicles have become quieter according to EU regulations, the noise exposure of the population does not seem to have diminished due to an increase of the number of vehicles. Therefore more emphasis is needed to reduce the noise, including further reduction of noise emissions of cars, trucks and motorcycles.
While there may be gaps in our knowledge, existing evidence clearly points the way to increasing emphasis on reducing the exposure to environmental noise. An important document demonstrating that noise is not only a nuisance, but also an important factor affecting physical health is the WHO's Burden of disease from environmental noise'1. The WHO's 'Night Noise Guidelines'2 and the 'Good practice guide on noise exposure and potential health effects'3 from the European Environment Agency (EEA) provide valuable guidance.
Dr Wolfgang Babisch Umweltbundesamt (Federal Environment Agency), Germany