The Wind Turbine Noise and Health Study, conducted over a four-month period in 2013, involved more than 1,200 residents in southwestern Ontario and P.E.I., whose homes were located at various distances from almost 400 of the electricity-generating structures in 18 wind-turbine developments.
The use of turbines to generate electricity by harnessing the wind — whether clustered on land in so-called farms or anchored offshore in lake or ocean floors — is controversial, and reaction to release of the study findings Thursday reflected long-established divergent opinions.
The study found no link between wind-turbine noise and respondents' reports of sleep disturbances, dizziness, tinnitus, migraines or chronic headaches, increased blood pressure or ongoing health conditions such as heart disease, chronic pain or diabetes.
"None of these were associated with wind turbine noise exposure, nor was perceived stress," a Health Canada spokesman said during a technical briefing with reporters.
"Some people did report these conditions. Some people had higher levels of perceived stress, higher blood pressure and so on," said the spokesman. "But they were not linked to noise."
However, the study did find a relationship between increasing levels of wind turbine noise and residents' annoyance related to that noise, as well as to vibration, shadow flicker from the rotating blades, and aircraft warning lights atop the towers.
When measured noise levels exceeded 35 decibels, the study found there was a concurrent increase in community annoyance.
"That's interesting because that's much lower than you would see with other sources of noise like road traffic or rail or aircraft noise," said the spokesman, noting that "the annoyance in Ontario was more than three times higher than it was in P.E.I.," though the researchers don't know why.
The "annoyance" factor should not be viewed as trivial: the World Health Organization considers this type of annoyance to be a health effect; Health Canada sees it as more of a health indicator, the spokesman said, adding that there's some medical evidence that annoyance is a mild stressor and could be associated with some health effects.
"We did find that people who were highly annoyed were more likely to report other health effects, such as migraines, tinnitus, sleep disturbance, perceived stress, and they also had higher levels of measured cortisol and blood pressure."
"These are statistical associations and they do not mean that annoyance is causing these health effects."
Sherri Lange, CEO of the organization North American Platform Against Wind Power, reacted negatively to the findings, saying the design of the study was poor and its findings, as a result, are disappointing.
Lange said the conclusions are disheartening to people who live near wind turbines and feel their quality of life has been severely diminished, to the point where some have chosen to leave their homes.
"Also, we are very tired of the word annoyance," she said. "Annoyance is a word that you use when your tire is flat, or when you are late to work, or when you spill a carton of milk. To use this Pablum word in the context of the suffering of people whose lives are literally shattered by industrial wind is, frankly, offensive."
However, the Canadian Wind Energy Association (CanWEA), which represents the wind-power generating industry, welcomed the findings.
"Based on the summary, the Health Canada study is an important new addition to scientific research on wind turbines and human health," said CanWEA president Robert Hornung. "The balance of scientific evidence to date continues to show that properly sited wind turbines are not harmful to human health and that wind energy remains one of the safest and environmentally friendly forms of electricity generation."
Health Canada says the study is the most comprehensive of any around the world that have looked at the potential effects of wind turbines on human health.
To conduct the study, researchers from Health Canada and Statistics Canada went door-to-door to households — 1,011 in Ontario, 227 in P.E.I. — to administer a detailed questionnaire to one adult resident in each home.
A subgroup of residents also had measurements taken of health-related indicators, including hair analysis to determine long-term levels of the stress hormone cortisol, blood pressure, resting heart rate and sleep patterns. Sleep quality was assessed for seven days using a wrist device that measures a person's movement patterns while in bed.
The study found no cause-and-effect relationship between wind-turbine noise and any negative health indicators identified through this testing, but Health Canada says the study alone cannot provide definitive answers and more research may be needed.
Researchers also collected more than 4,000 hours of noise measurements in all, with the highest level reaching 46 decibels. While direct health effects are not expected as a result of exposure to 46 decibels of sound, the WHO says levels in excess of 40 to 45 decibels can cause disturbed sleep, the spokesman said.
"That's just the noise result that we found. We did not, however, find any evidence of sleep disturbance in our study, despite the fact that we measured up to 46 decibels."
Health Canada stressed that the results cannot be generalized to other areas of Canada where wind turbines have been erected.
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