Board needs to find that turbines will not create conditions inimical to the public health.
Two utility scale wind turbines with a blade tip height of approximately 410 feet are proposed for land abutting residential neighborhoods in Charlestown. The Charlestown Zoning Board will conduct a hearing for a special use permit to build and operate the two wind turbines on Tuesday, May 21, at 7 p.m. at Charlestown Elementary School.
In their decision, the Zoning Board must make positive findings. One of those findings must be that the proposal will not result in adverse impacts or create conditions that will be inimical to the public health. We do not believe they can make this positive finding.
On Wednesday, May 8 at the Cross Mills Public Library, Dr. Harold Vincent, URI Associate Research Professor, explained how infrasonic sound is created by large wind turbines and how it may effect humans. Harold Vincent is a faculty member in the Department of Ocean Engineering at URI’s Graduate School of Oceanography. He is a member of the Acoustical Society of America and other organizations. Dr. Vincent is working with the Rhode Island Office of Energy Resources to create siting guidelines governing wind turbines.
Both wind turbine advocates and opponents agree that the effects of wind turbine infrasonic noise (i.e. below 20 Hz) on humans is at the early exploratory phase. The noise generated by wind turbines is unusual, containing high levels of very low frequency sound (infrasound – sound which is outside the hearing range of humans). The larger the wind turbine the higher the level of infrasound. There have been no systematic long-term studies of prolonged exposure to such sounds on humans or other animals.
Dr. Vincent explained that the very low frequency sounds and infrasound generated by large wind turbines is unrelated to the loudness of the sound that you hear. Infrasound can only be measured with a sound level meter capable of detecting it.
Land based wind turbine proponents will tell you the audible sound level generated by large wind turbines is low. They will claim that at about 1000 feet away, the sound of a wind turbine generating electricity is likely to be about the same level as noise from a flowing stream. Using this measurement, wind turbines appear to be very quiet. Even if claims about audible sound were true, (and there is much evidence to dispute these claims and support that audible sound is a problem) this characterization of wind turbine noise ignores the very significant infrasound component of the sound.
Dr. Vincent related research conducted at Washington University that is peer-reviewed, accepted, and in press in the Journal of the Acoustical Society of America. This research has recently shown that the outer hair cells of the cochlea are stimulated by low frequency sounds. Sounds that are outside of the range of human hearing, create a biological response.
The cochlea is the auditory portion of the inner ear. The cochlea receives sound in the form of vibrations, which cause the stereocilia (hair-like structures) to move. The stereocilia then convert these vibrations into nerve impulses which are taken up to the brain to be interpreted. The outer hair cells of the cochlea are stimulated by low frequency sounds at levels much lower than the inner hair cells. This research shows that infrasounds that cannot be heard do influence inner ear function. What is certain is that there is a biological response to the low frequency sounds of large wind turbines. The health effects of this biological response certainly deserve further study.
The pathway of conscious hearing is very well studied and established. It goes from the inner hair cells of the cochlea, through type I auditory nerve fibers, to the brain. The outer hair cells of the ear (the ones that are sensitive to infrasound) do not connect to this conscious pathway. They connect to the type II nerves, then to granule cells that are connected into areas related to attention and wakefulness. Stimulation of this pathway could wake you up.
Neighbors of large wind turbines often complain of sleep disturbance. Chronic sleep deprivation can lead to high blood pressure, memory problems, and a cascade of other health problems.
Proponents of siting large wind turbines near residential areas will often cite the Massachusetts Department of Environmental Protection (MassDEP) study on health effects of Wind Turbines. This report does acknowledge sleep disturbances for neighbors of wind turbines. It also says, “A possible coupling mechanism between infrasound and the vestibular system (via the Outer Hair Cells in the inner ear) has been proposed but is not yet fully understood or sufficiently explained.”
Since the MassDEP report was released, a biological response to the low frequency sound of large wind turbines has been scientifically demonstrated. It is possible that this biological response results in sleep disturbance. Sleep disturbance is a frequent complaint of neighbors of utility scale wind turbines. Sleep disturbance that goes on for years results in serious health problems.
Wind energy may become a significant part of American energy production. Where turbines are sited is critical to the success of the industry. Putting turbines where they conflict with people, creates resistance to the industry and may indeed harm neighbors. A case may be made for the need for research and long term studies to determine the exact nature of the heath effects, but should our own citizens be the guinea pigs for those studies?
Knowing that the low frequency sound produced by large wind turbines creates a biological response with as yet unknown consequences to health, the Charlestown Zoning Board cannot make a positive finding that the proposal will not result in adverse impacts or negatively impact the health of the neighbors.