[This post has been published in Spanish El País-Materia]
Noise is one of the most important environmental stressors and represents a public health concern. Despite emerging evidence from experimental and epidemiological studies, the effects of noise on health have captured little attention and are often disregarded.
Nowadays in Europe, 100 million people -one in five people- are exposed to high outdoor levels of road traffic noise
Noise is defined as “unwanted sound”. Road traffic is the most common noise source both inside and outside cities, followed by trains and airplanes. Road traffic noise alone is categorized by the World Health Organization (WHO) as the second most harmful environmental stressor in Europe, behind only air pollution.
In 1999, WHO recommended that noise levels outdoors should not exceed 55 dB during the daytime. In 2009, WHO further recommended a night-time guideline value of 40 dB outdoors to prevent noise-related adverse health effects, with an initial goal of 55 dB.
Nowadays in Europe, 100 million people -one in five people- are exposed to high outdoor levels of road traffic noise (above 55dB) and 32 million to very high outdoor levels of road traffic noise (above 65 dB). In Spain, numbers are higher, with one in four people exposed above 55 dB.
Regular environmental noise levels have been associated with annoyance, sleep disturbance, cognitive problems and with cardiovascular disease
It is well-known that exposure to high noise levels can cause direct effects on audition. However, regular environmental noise levels have been also associated with annoyance, sleep disturbance, cognitive problems, and with cardiovascular disease, particularly ischeamic heart disease. Recent studies also suggest that road traffic noise could be associated with diabetes and obesity.
Noise causes 72,000 hospitalizations and 16,600 premature deaths annually
The health burden due to noise in Europe is large. The European Environment Agency has calculated that almost 32 million Europeans are annoyed by noise, 13 million suffer from sleep disturbance due to noise, and that noise causes 72,000 hospitalizations and 16,600 premature deaths annually. In addition, a recent health impact assessment study for Barcelona (Spain) published by ISGlobal has estimated over 1,200 premature deaths attributable to local air pollution and noise levels. In turn, a subsequent study observed that road traffic noise accounted for 36% of the total burden of disease attributable to urban and transport planning, a higher percentage than that attributable to air pollution.
Noise may affect health through different biological mechanisms. Stress due to noise can lead to annoyance while we are awake, which can affect quality of life, change our behavior and affect health. Stress due to noise can also lead to physiological reactions such as hormone release and increased blood pressure that seem to be particularly important while sleeping, even if we do not perceive noise and do not wake up. Noise may also affect health through sleep disturbance, which is increasingly recognized to alter the metabolism, and among others, to disrupt glucose metabolism or dysregulate appetite. Under long-term exposure to noise, the different reactions could lead to chronic alterations, which would explain, for example, the association between long-term exposure to road traffic noise and cardiovascular diseases or the recent findings for the association of exposure to road traffic noise with diabetes and obesity.
Member states are required to report population noise exposure for agglomerations of more than 100,000 inhabitants and prepare mitigation action plans under the European Noise Directive. Noise levels are mapped and made publicly available. For example, the noise map for Barcelona can be found in the city council website and people can check the noise level at their street address in this website. Examples of action plans to mitigate noise include replacing road surfaces, limiting traffic flow and decreasing speed limits. The most efficient action to reduce exposure to noise is to reduce and/or eliminate the sources of noise. Having access to a quiet areas to escape from noise is crucial. Thus it is also important to protect already existing quiet areas.
Urban planning can play an important role to reduce noise levels
Urban planning can play an important role to reduce noise levels, but also to reduce air pollution levels, and to promote healthy lifestyles, facilitating a shift from motor vehicle transportation to public and active transportation. Green spaces also mitigate noise and provide quiet areas.