Despite their clean-power capabilities, wind turbines and the low-frequency noise they emit has taken the rap for a number of negative health effects. A running count of just over 30 symptoms, including stress, fatigue, nausea, tinnitus or ringing in the ears, diabetes, and even cardiovascular disease, have been blamed, in some cases, on wind turbines over the last few years.
Although some may claim there isn’t enough scientific literature to either negate or uphold these allegations, Dr. Robert McCunney, an Occupational Medicine Specialist in Boston who’s done research with the Massachusetts Institute of Technology (MIT), disagrees. He presented a review of related health literature at a recent Canadian wind conference, and maintained that there is plenty of credible, peer-reviewed information to draw from.
“There is a rich scientific literature on occupational noise exposure and health, and on environmental sources of noise and health, which has looked at everything from airports to highways, construction sites, and so forth,” he said, “including wind turbines.”
The challenge, however, is in trying to decipher how many potential factors contribute to a specific health issue. “Just like when researchers are trying to determine the risk factors associated with lung cancer or heart disease, when there are many factors that can lead to an outcome of interest, how does one pinpoint a specific cause or correlation?”
Fortunately, a statistical technique called multiple regression analysis is commonly used to sort through and evaluate contributing factors. It‘s an effective technique for predicting how multiple factors that may be associated with an outcome contribute individually.
“Through multiple regression analysis, risks associated with self reports have been evaluated to sort out the role of wind-turbine noise in comparison to other factors,” explained McCunney. These factors can include an individual’s attitude toward wind turbines in general, the visual appeal of wind turbines, and the potential for economic gains related to living near wind turbines. “One common outcome measure used in environmental noise studies is annoyance. But when looking at these issues, noise is actually low on the list of contributing factors when it comes to being annoyed, even though we focus on it a lot,” he said.
McCuuney and a research team at MIT recently published a study in the “Journal of Occupational and Environmental Medicine,” based on a grant the Canadian Wind Energy Association (CanWEA) gave to MIT to review the scientific literature on noise, wind turbines, and health. Rather than starting from scratch with a brand new study, the team went to PubMed, which is the National Library of Medicine’s database of over 23 million peer-reviewed and indexed papers.
To sort through the material, they used key search terms with the purpose of answering three main questions:
- Is there sufficient scientific evidence to conclude that wind turbines adversely affect human health?
- Is there sufficient scientific evidence to conclude that psychological stress, annoyance, and sleep disturbances occur as a result of living near wind turbines — and do they lead to adverse health effects?
- Is there evidence to suggest that infrasound and low frequency from turbines have unique potential health effects not associated with other source of environmental noise?
Based on these questions, McCunney and his team narrowed down the search parameters even further and looked at these four categories:
- Noise assessment
- Epidemiology studies
- Central nervous system effects
- Individual risk factors
“The last point is important because it seeks to understand why it is that some people report annoyance from turbine noise and others don’t,” McCunney explained. “This is a fundamental question in medicine today. For instance: why do some people get breast cancer and others don’t? Why do some people get COPD from smoking and others don’t?”
McCunney pointed to studies that have purposely exposed people to infrasound and low-frequency sound (sound waves with frequencies below the lower limit of human audibility much like those emitted by wind turbines). “Astronauts back in the late 1960’s were exposed to infrasound at levels from 130 to 140 decibels for 24 hours with no adverse health affects,” he said.
Acceptable noise-level regulations are much lower today. For example, in Ontario noise levels must be lower than 40 dB(A) at the outside of a residence. “There’s no doubt that infrasound is emitted by turbines, but levels at customary distances from homes – and here in Ontario, it’s 550 meters or greater – basically approach background levels.”
When you think about it, McCunney added, you’re actually being bombarded by infrasound every day — from cars, traffic, aircraft, household appliances. “Even your heartbeat is infrasound, which is why physicians need a stethoscope to hear it,” he said. “Noise simply does not correlate well or at all with objective sound measurements or calculated sound pressure.”
While noise might not closely relate to feelings of annoyance, when it comes to turbines, there are other factors that can affect people’s level of irritation. This includes some of the points mentioned earlier, such as:
- Attitudes toward wind energy and turbines in general,
- Attitude toward the visual impact of wind turbines,
- Duration of time turbines are in operation,
- Personality characteristics of individuals living near turbines, and
- Whether individuals stand to benefit financially from the presence of turbines.
“These factors have all related to self reports of annoyance,” said McCunney, who pointed out that all of this data is based on questionnaires that ask individuals to rate how annoyed they are (e.g. Are you very annoyed, are you annoyed, are you somewhat annoyed, or not at all annoyed?) “Overall, the perception of annoyance and the sound of wind turbines are more strongly related to people’s attitudes toward wind turbines than to the actual noise level occurring at a site.”
Economics can also play an interesting role. At least in Dutch studies, researchers have begun to eliminate those people studied that gained economically from wind turbines because of a concern that they will skew the results. The reason: “Economic benefits tend to strongly mitigate the impact of wind turbine sounds when reporting annoyance, and this has been demonstrated in numerous studies,” said McCunney.
Sleep is another factor the MIT team considered. “Lack of sleep is a major reason people come into see physicians, and it’s a major cause of morbidity,” he added. According to the World Health Organization’s Nighttime Noise Guidelines, sleep disturbance has been associated with sound pressures of greater than 45 decibels but not with other measures of health or well being.
“Granted, there is a lot of research on sleep-related health effects available, and effects of lower sound levels during sleep may be noted. However, once you get down to 40 decibels, there’s really no appreciable sleep awakening.”
But even just hearing that a wind farm might be developed in a region has caused anxiety and sleep problems in some people. “Nocebo, or the opposite of a placebo effect, is the anticipation that you will get worse in a certain setting. Controlled lab evaluations have supported the notion that annoyance and other complaints may reflect, at least in part, one’s preconceived notion or perception about wind turbines and noise,” McCunney said.
For example, when people were exposed to infrasound before and during high and low-expectation noise, their reactions matched their earlier perceptions. So when exposed to turbine noise, people who didn’t think they’d have a problem with it didn’t, and those who thought they would, did experience negative effects. “It really does go to show you the power of the mind,” he added.
Sleep and stress aside, what about that list of some 30-plus issues and some potentially life-threatening diseases? McCunney said that numerous studies have looked at health problems related to living near wind turbines and no health links have been found between noise levels and risks of diabetes, hypertension, tinnitus, or cardiovascular diseases.
“To the contrary. The studies show that people who were exposed to lower noise levels had more disease than those exposed to higher or louder levels of noise from wind turbines. The results are somewhat counter-intuitive.”
Nevertheless, McCunney said it’s still important that when people report symptoms, regardless of whether they think they are related to living near wind turbines or not, that they need to be thoroughly evaluated to reach a proper diagnosis. “It’s really important to listen first and take complaints seriously.”
He added that cases like these involve a lot of potential factors. “Having said that, I’ve been in practice for over 35 years and I don’t want to seem dismissive, but I’ve never seen a hazard that’s capable of causing all of the problems wind turbines have been blamed for- about 32 symptoms. Even cigarette smoke or asbestos doesn’t cause that many problems. How can one issue cause 32 different symptoms, affecting eight or nine organ systems? It just doesn’t seem plausible to me.”