The following is from
Health Canada
Health Impacts and Exposure to Sound From Wind Turbines: Updated Research Design and Sound Exposure Assessment
Summary
The last decade has seen a sharp increase in wind turbine generated electricity in Canada. As of November 2012, Canada's installed capacity was 5.9 Gigawatts, providing 2.3 percent of Canada's current electricity demands. The wind energy industry has set a vision that by 2025 wind energy will supply 20% of Canada's electricity demands. Some public concern has been expressed about the potential health impacts of wind turbine sound (WTSFootnote i). The health effects reported by individuals living in communities in close proximity to wind turbine installations are poorly understood due to limited scientific research in this area. This is coupled with the many challenges faced in measuring and modeling WTS, including low frequencies, which represent knowledge gaps in this area. The continued success and viability of wind turbine energy in Canada, and around the world, will rely upon a thorough understanding of the potential health impacts and community concerns.
Health Canada is collaborating with Statistics Canada on an epidemiological study to evaluate measurable health endpoints in people living in 8-12 communities at distances up to 10km from wind turbine installations. Measured endpoints include an automated blood pressure/heart rate assessment, hair cortisol concentrations and sleep actimetry. The seven days of sleep measurement data will be analyzed in relation to synchronized wind turbine operational data, providing the strength of a repeated measures design that incorporates objectively determined health outcome measures.
In addition, self-reported data will be collected during an anticipated 30-35 minute face-to-face computer-assisted interview at participants' homes. The questionnaire instrument includes, but is not limited to, modules that probe endpoints such as noise annoyance, health effects, quality of life, sleep quality, perceived stress, lifestyle behaviours (e.g., cigarette smoking, alcohol consumption), prevalent chronic disease and property value impacts. Following completion of the questionnaire, subjects will be invited to participate in the physical health measures collection portion of the study.
Both self-reported and measured endpoints will be analyzed in relation to modeled WTS levels as a function of frequency (i.e. permitting A- C and G-weighting assessments). Modeled WTS will be validated and adjusted (if necessary) based on measurements taken indoors and outdoors in a sub-sample of dwellings. The targeted sample will consist of 2000 dwellings at setback distances ranging from less than 500 metres to distances of up to 10 kilometers randomly selected from communities in the vicinity of 8 to 12 wind turbine installations. As sleep disturbance is a frequent health complaint associated with WTS in observational and case studies, one of the primary research objectives in the study is to quantify the magnitude of sleep disturbance due to WTS. Statistics Canada's experience in sampling from similar communities is that 20% of the 2000 dwellings that are initially targeted will be unoccupied. With a response rate of approximately 70-75% (among which around 20% will be within the closest distances) there should be sufficient statistical power to detect a 7% difference in the prevalence of sleep disturbances with 80% power and a 5% false positive rate (Type I error). Of course there is uncertainty in the power assessment because Health Canada's study is the first study to implement measured endpoints to study the impact that exposure to WTS may have on human health. Ultimately the results, while not definitive on their own, will contribute to the body of international peer-reviewed scientific evidence examining the health impact of WTS, and may also lead the way for supporting future studies examining this complex issue.
1 Background
In Canada, federal, provincial, territorial, and municipal levels of government share jurisdiction for regulating sound that could be harmful to Canadians. Through administration of the Radiation Emitting Devices Act, Health Canada has acquired expertise in acoustics, which is provided upon request to other federal government departments responsible for carrying out environmental assessments under the Canadian Environmental Assessment Act 2012. Provincial and territorial governments have legislation, guidelines, or municipal by-laws, which may apply broadly or only to specific project types or sectors. With respect to wind turbines, the location and any applicable sound level limits fall under the jurisdiction of provincial governments.
Wind turbines are becoming an increasingly common power generation option across North America and in many parts of the world. Those who endorse wind energy view it as a viable and environmentally friendly alternative to fossil fuels. Since the announcement of the Government of Canada's renewable energy initiatives, there has been a steady rise in the number of wind turbine installations across Canada. According to the Canadian Wind Energy Association (CANWEA) wind capacity is currently surpassing 5.9 Gigawatts (GW) - enough to power over 1.4 million homes (CANWEA, 2012). By 2015, wind capacity is expected to reach 10 GW, which is a 20-fold increase over 2000 levels and by 2025, it is envisioned that 20% of Canada's electricity will be wind power generated (Canadian Wind Energy Association, 2005).
With the surge in wind farm development there has been considerable attention generated internationally and nationally by advocacy groups, concerned citizens and media on the potential health impacts from exposure to the sound emitted by wind turbines. Some groups have expressed concern that the presence of wind turbines within the vicinity of residential dwellings may not only have a negative impact on property values, but may also pose a public health risk to nearby residents. Observational and case studies have disclosed a broad range of health effects claimed to be associated with WTN including headaches, migraines, sleep disturbance, negative effects on psychological well-being, among others. Wind turbines are often situated in rural communities where background sound levels are typically low. Therefore, WTN may be particularly problematic for rural residents as it may be more noticeable and they may experience large changes in sound levels with unpredictable operating times due to variable wind conditions. It is also important to note that not all studies in this area have found significant associations between exposure to sound from wind turbines and self-reported measures of health that go beyond sleep disturbances and annoyance (see review by Pedersen, 2011).
The World Health Organization (WHO) defines health as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity" and, "the extent to which an individual or a group is able, on the one hand, to realize aspirations and to satisfy needs, and on the other, to change or cope with the environment" (WHO, 1999). The WHO's Night Noise Guidelines for Europe (2009) cites sleep disturbance as a potential indirect health impact of environmental noise for yearly averaged night time outdoor sound levels at the residence higher than 40 A-weighted decibels (dBA). It has been reported in some studies that the 40 dBA sound level may be exceeded at some residences, suggesting the potential for sound from wind turbines to disturb sleep among sensitive individuals (Pedersen and Waye, 2004; Pedersen et al., 2009; Krogh, 2011; Harry, 2007; Shepherd, 2011; Pierpont, 2009; Nissenbaum et al., 2012).
Wind turbine sound includes the production of lower frequencies (Møller and Pedersen, 2011). Once audible, lower frequency sound is more annoying than higher frequencies (Leventhall, 2004). It also travels further than higher frequency sound (Shepherd and Hubbard, 1991), and can penetrate structures such as homes without much reduction in energy (Møller and Pedersen, 2011). Inside the home, low frequency sound can cause objects to vibrate or rattle (ANSI, 2005).
2. Impacts on Health and Well-being
Health Canada's ability to provide advice on exposure to sound from wind turbines has been challenged by limited peer-reviewed scientific research related to both the character of WTS, in particular low frequencies, and a lack of Canadian prevalence data on community complaints and self-reported health impacts from studies with rigorous methodological designs.
Assessment of health outcomes, potentially related to sound exposure from wind turbines, has so far been limited. Among the various outcomes assessed, the only reproducible findings linked to WTS have been based on measures of social and psychological well-being or quality of life and the extent to which they disturb various human activities (i.e. sleep disturbance). Wind turbines, and the sound they produce, continue to receive attention as the numbers of wind-power projects increase in line with national and provincial clean-energy targets. Concerns of individuals regarding wind turbine installations include, but are not limited to, nausea, vertigo, tinnitus, heart palpitations, stress, blood pressure spikes, sleep disturbance and annoyance resulting from the noise that wind turbines produce (Harry, 2007; Pierpont, 2009; Krogh, 2011). An extensive review of these and other studies is planned to coincide with the completion of the Health Canada study.
To date, there have been no field studies that have included objectively measured health-related endpoints in their study design, which could lend support to some of the self-reported claims derived from questionnaires. These studies would offer a distinct advantage over those based on self-reported health questionnaire data alone. Studies that use self-reporting alone may be prone to participation bias, and also awareness bias where individuals may tend to over report symptoms or health conditions because of a heightened awareness of possible health impacts from media, advocacy groups etc. Similarly, there may be situations where individuals under report conditions.
Objectionable environmental sound (i.e. noise) tends to be a concern mostly among urban or residential settings that may be impacted by highways, railways, and airports. However, more recently, wind power projects have been introduced in rural environments, where man-made sound sources tend to be less common than in urban areas. Regardless of the community type, exposure to prolonged or excessive sound may directly or indirectly affect the health and well-being of individuals. Because of the health risks that have been associated with sleep disturbance (for any reason), long-term sleep disruption may also be considered an indicator of a possible health impact because it may lead to chronic illness. Although no study to date has quantitatively measured sleep disturbance in populations living in the vicinity of wind turbines, self-reported impacts on sleep have been associated with exposure to WTS or distance to wind turbines in some, but not all field studies (see review by Knopper and Ollson, 2011; Pedersen (2011), Nissenbaum et al., 2012).
Considering the scientific evidence on the lowest observed adverse effect level for sleep disturbance, the WHO identified an average annual outdoor nighttime sound level of 40 dBA as a recommended limit to protect public health from night noise, including that of the most vulnerable groups such as children, the chronically ill, and the elderly. A-weighting has become ubiquitous in characterizing community sound sources because it accounts for the relative loudness perceived by the human auditory system, i.e., it filters out low and high frequencies. For this reason, there has been criticism of an A-weighted base limit for a source that contains low frequencies such as large scale wind turbines. To complement the A-weighted outdoor levels, an explicit accounting for low frequencies is appropriate for wind turbines. Outdoors, the A-weighting tends to overestimate the perceived loudness of low frequencies from wind turbines. Conversely, A-weighting may underestimate the indoor awareness of wind turbine sound due to resonances and rattles that can sometimes be caused by low frequencies.
The statistical odds of self-reporting annoyance have been found to be consistently associated with increasing WTS levels (Pedersen and Waye, 2004 and 2007; Pedersen et al., 2009). This relationship has been found to be moderated by economic and visual effects (Pedersen et al., 2009; Pedersen and Larsman, 2008) so that those with economic benefits are generally less annoyed, but those who dislike the visual impacts tend to self-report higher levels of annoyance. In both cases, these interactions make it difficult to isolate the WTS from the community response.
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