The renewable energy debate can be complicated, as there are many variables in terms of all of the energy costs for the entire lifecycle of each energy source, the problems of intermittent energy, and the complex effects on the environment. Focusing on the direct health effects at least deals with a specific question for which there is some published evidence.

The health effects of polluting forms of energy has been estimated in various publications, and is staggering. A 2011 study found that in the US alone the health costs of air pollution were about $131 billion. A UK study attributes 40,000 deaths in the UK per year to air pollution. So, from a public health perspective, there is good reason to phase out fossil fuels, especially coal, as they are highly polluting forms of energy.

But we do have to consider the overall health effects of any energy production with which we replace fossil fuels. Wind turbines have come under criticism for various reasons, including killing birds and bats, being an eyesore, reducing quality of life, and negative health effects from the noise and infrasound they generate. None of these claims hold much water, but let’s take a closer look at the health effects.

Wind turbine syndrome

The most plausible health concern from proximity to wind turbines is that their noise can disturb sleep. Chronic sleep disturbance is a clear health risk, and so if this is true it would inform minimum safe distances between wind turbines and residential areas. Another concern is that the constant noise or even light flickering caused by the moving blades are a source of stress, which is its own health risk. Less plausible is the claim that some people are sensitive to the infrasound created by wind turbines, which cannot be heard but can have an effect none-the-less.

Here is what reviews of the published evidence have found so far:

A 2013 review concluded that there is some evidence that infrasound (sound of too low a frequency to hear) can affect the vestibular system, and so WTS is at least plausible.

A 2014 systematic review of possible WTS concluded:

Exposure to wind turbines does seem to increase the risk of annoyance and self-reported sleep disturbance in a dose-response relationship. There appears, though, to be a tolerable level of around LAeq of 35 dB. Of the many other claimed health effects of wind turbine noise exposure reported in the literature, however, no conclusive evidence could be found. Future studies should focus on investigations aimed at objectively demonstrating whether or not measureable health-related outcomes can be proven to fluctuate depending on exposure to wind turbines.

A 2015 review concluded:

In conclusion, there is some evidence that exposure to wind turbine noise is associated with increased odds of annoyance and sleep problems. Individual attitudes could influence the type of response to noise from wind turbines. Experimental and observational studies investigating the relationship between wind turbine noise and health are warranted.

There was also a large Statistics Canada study looking at data through 2013 which found:

Statistics Canada study found no direct link between residents’ distance from wind turbines and sleep disturbances (as measured by sleep assessments and the Pittsburgh Sleep Quality Index), blood pressure, or stress (either self-reported or measured via hair cortisol).

Data limitations

The major limitation on all these studies of possible effects of living near a wind turbine is that they are observational. Obviously you cannot randomize people to live near a wind turbine. There is also no way to blind subjects to their proximity. Some of the data is based on surveys, which introduces an element of selection bias.

But even the more rigorous studies are largely subjective. There is good reason to suspect that confounding variables may be dominant here. A 2014 study reviewed psychological factors which have been shown to influence reports of health effects from wind turbines. Subjects were more likely to report negative symptoms if they found wind turbines annoying, if they thought they were an eyesore, and if they did not gain any economic benefit from them.

A 2017 Australian study found that one’s political view toward wind turbines largely determine how symptoms and alleged health effects are interpreted – specifically, are they caused by proximity to wind turbines.

Plausibility

How plausible is a direct biological effect from wind turbines (as opposed to a psychological effect from annoyance)? There is some evidence to suggest that infrasound can have an effect on the vestibular system of sensitive individuals. This, however, has not been directly correlated with the existence of symptoms.

One objective question to answer is – how loud are wind turbines? This depends on the exact model and, of course, how fast the wind is blowing. But existing models in use generate about 105 decibels (about as loud as a lawnmower) at the source. The intensity of this sound drops off with distance. At 100 meters the noise is down to about 50 decibels, which is as loud as a medium-sized window air conditioner. At 300 meters the noise is at 40 decibels, which is as loud as a typical refrigerator. (In the decibel scale, which is logarithmic, a change in 10 decibels in a loudness factor of 10, so 50 decibels is 10 times louder than 40 decibels.)

Wind turbines are placed at least 300 meters distant from residential areas. It is definitely interesting that there is no “air conditioner syndrome” despite the fact that air conditioners generate 10 times as much noise as the closest possible wind turbine. Since most homes in developed countries are likely have a refrigerator, the existence of a wind turbine 300 meters away should not add much to the background noise.

Conclusion: Semi-plausible, mostly subjective

The existing evidence indicates that concerns over a wind turbine health syndrome are only semi-plausible. Further, the evidence does not support any objective measure of negative health effects (like blood pressure), but does show an effect on subjective symptoms. However, these results are questionable for two main reasons – they are subject to bias, and tend to correlate with negative political or personal attitudes toward wind turbines.

Unfortunately the evidence is not of sufficient quality to end debate on the question. Further study will help, but also will likely not resolve the debate, because we cannot gather gold-standard blinded and controlled data.

Technological advances are diminishing the problem, however, as newer models of wind turbines are quieter than older models. It seems prudent to prioritize this feature of the technology as it further advances. But given that much of the opposition to wind turbines is political, more study and technological advances will probably not eliminate it.

Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the president and co-founder of the New England Skeptical Society, the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also contributes every Sunday to The Rogues Gallery, the official blog of the SGU.