Human Health Risk Associated With Wind Turbine Noise
Wind turbines have the potential to contribute to global electricity generation as a clean, emission-free, and increasingly cost-effective energy solution. Wind power is positioned to contribute, along with other renewable energy sources, increasingly to a reduction in global greenhouse gas emissions while becoming less expensive as technologies improve (Sims et al 2003) Despite this, wind turbines remain controversial due to the perception that they pose a human health risk. In popular literature, the term “Wind Turbine Syndrome” has been used to describe the perceived suite of health effects associated with wind turbine noise (Knopper and Ollson 2011; Bolin et al 2011) The major issues arise from the wind turbines’ structural features and wind turbine noise (Knopper and Ollson 2011) with the latter largely being the source of public concern. Prolonged exposure to low frequency sound may cause difficulty concentrating, fatigue, sleep disturbance and physiological stress (Bolin et al 2011; Pedersen and Persson Waye 2007). Popular literature claims more serious symptoms such as cardiovascular disease and epilepsy are associated with wind turbine noise but these effects have not been proven. The potential for health effects has led to the development of minimum setback distances for wind turbines near residential areas. For example, the Ontario Renewable Energy Approval (REA) Regulation states that “a minimum setback distance of 550 m must exist between the centre of the base of the wind turbine and the nearest noise receptor”. The 550 m distance was developed through noise modeling under worst-case conditions to give a conservative estimate of the required distance to attain an A-weighted sound level of 40 decibels (Ontario Ministry of the Environment).
In regards to the construction of wind turbines, these conflicting sources of information have often led to reluctance of local residents. “Not in my backyard” (NIMBY) is a common term cited in the literature in reference to the feelings of people living in areas where wind turbines have been proposed. In fact, wind turbine noise has been shown to annoy people who can see them more than people who cannot. In addition, people who benefit economically from the wind turbines report less annoyance due to noise than others (Pedersen et al 2009). Clearly the uncertainty surrounding wind turbine noise is problematic. This is exacerbated by the fact that large wind turbines for energy production are relatively new technology and few scientific studies of potential long-term adverse health effects exist.
Noise with infrasound (1–20 Hz) and low frequency (20–200 Hz) components, such as that associated with wind turbines, may be more disruptive to the health and well-being of humans than sounds with higher frequencies (Bolin et al 2011). Various studies have shown that loudness and annoyance increases more rapidly with increasing sound pressure for low frequency sounds than those with higher frequencies (Moller and Pedersen 2004, Leventhall 2004). While low frequency noise or infrasound is emitted by other common sources (vehicular road traffic, air transportation and industry) wind turbine noise has been perceived to be more bothersome, likely due to the “swishing” sound caused by the rotation of the blades, variability (i.e. from wind speed changes) and lack of nighttime abatement (Pedersen et al 2009). A review by Salt and Hullar 2010 is often cited as proof of adverse effects caused by wind turbine noise. This paper, which focuses on the effects of infrasound, suggests that infrasound generated by wind turbines has the potential to causes changes to the human inner ear resulting in adverse health effects. Bolin et al 2011 and Knopper and Ollson 2011 both state that the lack of empirical evidence connecting this statement with wind turbine noise experienced at the residential level discredit this finding. Bolin et al 2011 also argue that despite the existence of two published studies showing potentially damaging levels of infrasound being emitted from wind turbines, these studies were conducted at distances much closer to the turbines than minimum set-back distances. Thus, noise from these studies could not possibly be at the same level it would be near residential homes.
It is difficult to sort out which residents are expressing the NIMBY attitude and which residents are truly sensitive to wind turbine noise such that their health is affected. Most studies state “annoyance” as the main form of discomfort to people living in the vicinity of wind turbines while evidence for other health effects is lacking, although there has been some correlation between wind turbine noise and sleep disturbance (Bolin et al 2011). Chronic, long term exposure to something causing stress and sleep disturbance such as wind turbine noise, could potentially lead to cardiovascular problems (Bolin et al 2011). In addition, there are members of the population who are more sensitive to sound than others, thus the potential for such health effects shouldn’t be dismissed. While the two recent review papers cited here (Bolin et al 2011and Knopper and Ollson 2011) agree that evidence of serious health problems caused by wind turbine noise is lacking, few, if any, long term studies exist. The collection of long term data from residents living near wind farms is warranted to determine if chronic effects exist in those exposed to low frequency noise emitted from wind turbines.
This showed up on CBC news this morning: http://www.cbc.ca/news/canada/saskatchewan/story/2013/09/11/saskatoon-community-wind-meeting.html. Would you support wind power in your community?