Indicator EN.5.a Outdoor noise levels
Why Is This An Indicator Of Health and Sustainability?
The health impacts of environmental noise depend on the intensity of noise, on the duration of exposure, and the context of exposure. The Environmental Protection Agency identifies a 24-hour exposure level of 70 decibels as the level of environmental noise which will prevent any measurable hearing loss over a lifetime.
Noise levels of 55 decibels outdoors and 45 decibels indoors are identified as preventing activity interference and annoyance. These levels of noise are considered those which will permit spoken conversation and other activities such as sleeping, working and recreation, which are part of the daily human condition. Source: Environmental Protection Agency, http://www.epa.gov/history/topics/noise/01.htm Long term exposure to moderate levels of environmental noise can adversely affect sleep, school and work performance, and cardiovascular disease.a
Noise affects sleep both by waking people up and reducing the quality of sleep. According to the World Health Organization, reductions of noise by 6-14 dBA result in subjective and objective improvements in sleep. Environmental noise is a risk factor for cardiovascular disease. Chronic road noise can affect cognitive performance of children including difficulty keeping attention, concentrating and remembering, poorer reading ability, and poorer discrimination between sounds.b The combination of noise and poor quality housing can have additive effects. In one study, a combination of these factors was associated with higher stress and stress hormone levels.c
A comprehensive synthesis of the noise heath effects and control is contained in the World Health Organization's Guidelines for Community Noise available at: http://www.who.int/docstore/peh/noise/guidelines2.html
The map illustrate 24-hour noise levels in San Francisco modeled using the Federal Highway Administration's Traffic Noise Model and based on local traffic count data. In addition, remote sensing data were used to estimate neighborhood-specific percentages of different types of vehicles on arterial versus non-arterial streets. Noise levels were measured directly on 218 streets and compared against modeled levels for validation. Field measurements are combined with noise modeling software to quantify noise levels in SF communities with special emphasis on understanding the effects of traffic volumes on the acoustical environment. Population exposure to noise was calculated by determining which residential lots were exposed to more than 60dB. Population estimates were attached to these lots using a dasymetric mapping technique and population exposure was summed by neighborhood to calculate neighborhood percents.
Multiple other factors influence the levels of noise in a neighborhood including topography, wind patterns, the density and type of traffic at different hours throughout the day and night, the presence or lack of trees, sound barrier walls and other noise obstructions, stationary sources of noise, the height and density of housing, etc.
- Dora C, Phillips M, eds. Transport, environment and health. WHO Regional Publications, European Series, No. 89. 1999. http://www.euro.who.int/document/e72015.pdf
- Noise and Health: Making the Link. London Health Commission, 2003. http://www.londonshealth.gov.uk/pdf/noise_links.pdf
- Evans G, Marcynyszyn LA. Environmental Justice, Cumulative Environmental Risk, and Health among Low- and Middle-Income Children in Upstate New York. Am J Pub Health 2004;94:1942-1944.