Today we’ve published a piece from Professor Simon Chapman of the University of Sydney School of Public Health summarising a study he co-authored, which found that complaints from nearby residents about wind farm noise or their effects on health tend to be relatively infrequent, but also vary greatly between wind farms and seem to be concentrated in the period after 2009.
Professor Chapman says this odd variation in the concentration of noise and health complaints in time and place suggests that whether a person suffers from wind turbines is a function of whether residents have been influenced by anti-wind farm lobby groups, rather than the wind turbines having physical characteristics which are inherently harmful.
No doubt the anti-wind farm groups such as the Waubra Foundation will dismiss this study as invalid. Two likely criticisms will be that the study relied on wind farm operator's own records of complaints (although supplemented by government submissions and media reports); and that Chapman is a biased researcher who has already made his mind up that wind turbines are not inherently harmful to people’s health.
In light of such criticisms it is worthwhile examining the underlying cause and effect argument behind the Waubra Foundation’s claim that wind farms are harmful to health.
THE CLAIM: INFRASOUND EMITTED BY WIND FARMS IS HARMING PEOPLE’S HEALTH
Sarah Laurie, who is the chief executive of the Waubra Foundation, argues that wind farms cause health problems based on the emission of infrasound or ultra low frequency sound which leads to stress and sleep deprivation. She states in a submission made to a Senate Inquiry that:
“Most health practitioners are well aware of the links between chronic severe sleep deprivation chronic stress and poor physical and mental health. This is exactly what residents living near wind turbines are experiencing, together with other specific symptoms directly correlating with acute exposure to this sound energy.
“Knowledge of the damage to health from exposure to infrasound and low frequency noise has been known for many years.
The link between chronic exposure to low frequency noise and chronic physiological stress, even when asleep, was clearly highlighted by Professor Leventhall et al in 2003.”
TRUE: INFRASOUND CAN CAUSE HEALTH PROBLEMS
This is entirely true. Professor Leventhall has done extensive work that has shown the potential for infrasound to be perceived by some people as an irritating sound, to the point where it can bother them so much that it becomes harmful to their well being.
This is probably why Laurie repeatedly and prominently references Leventhall in her public statements to support the argument that wind farms cause health problems. For example in a letter of complaint to Professor Chapman about his dismissal of wind turbine syndrome she states:
"Will you also explain why you and your co-reviewer of the Australian National Health and Medical Research Council’s “Rapid Review 2010”, .. failed to include the most important literature review detailing the peer reviewed published research of the then known adverse health impacts of low frequency noise on human health, written in 2003 for the UK Department of Food and Rural Affairs [DEFRA]?......Professor Leventhall, your co-reviewer, has publicly stated in expert testimony …that he has known about the symptoms of low frequency noise exposure or “wind turbine syndrome” for some time, and it is clear from his literature review from 2003 that this statement is correct."
Laurie also repeatedly references Leventhall’s research on other occasions, as recently as last month in a Victorian Civil and Administrative Tribunal hearing.
BUT NOT ALL INFRASOUND IS PROBLEMATIC
Now while it is true that Leventhall has found infrasound can cause health problems, it is actually infrasound of particular qualities which is potentially noticeable by humans to the point it could be so annoying as to be harmful to people’s health.
In a November 2012 submission Leventhall made to the same Senate Inquiry, from which I drew the Laurie statement, he explains in detail that it is a particular form of infrasound which causes problems:
“Dr Laurie misunderstands my 2003 DEFRA review….A problem which arises from people coming new to the study of low frequency noise, especially with wind turbines as the noise source, is that they do not know what has occurred in the past. Nearly every low frequency environmental noise problem has been caused by audible tones, and all the earlier publications relate to annoyance by low frequency tones.
“A tone concentrates the acoustic energy at one frequency, which is more annoying than a spread of energy. A spread of low frequency noise at a low level, such as is produced by wind turbines has not been considered a problem.”
To explain he provides two examples of the noise generated by machinery which create this annoying concentrated tone of infrasound. Example one is a large industrial fan which creates a spike of noise at the frequency of about 36 hertz which exceeds 90 decibels.
The thing is that infrasound is present almost anywhere you might go. It is generated by wind rustling in the trees, waves crashing on the beach, car traffic, and electric motors. As Leventhall points out, “We have evolved in the presence of natural infrasound and have been exposed for many years to infrasound of human origin.”
If any old infrasound made you unwell then we would all be desperately sick. But we aren’t and that’s because for infrasound to be problematic it needs to be unusually loud relative to what occurs in the underlying environment and concentrated at a particular frequency.
WIND TURBINES DO PRODUCE INFRASOUND BUT IT ISN’T OF A NOTICEABLE AND ANNOYING TYPE
Wind turbines, just like the wind itself, produce infrasound. But logically for it to be harmful it would need to be noticeable over and above what we are already subjected to without ill effect.
As detailed in Climate Spectator on 4 February, the South Australian EPA published a report finding that infrasound is not noticeably greater in households nearby to wind farms than other locations. Importantly, it also found that households nearby to wind farms did not suffer from a noticeable concentration of infrasound (a tone) at specific frequencies.
Leventhall also observes that the level of infrasound from wind turbines is low:
“Exposure to the low levels of infrasound from wind turbines has not been established as a health problem. Wind turbine infrasound levels are low, typically about 60dB at 10Hz at residences."
And he also notes that the the nature of the infrasound lacks a concentrated tone:
"Wind turbines produce a band of continuous low level noise, falling at about 5dB/octave as the frequency increases, …Work on air-conditioning noise has shown this to be a bland and unobtrusive spectrum. The results of investigations of tonal noises cannot be transferred to wide band wind turbine noise. Dr Laurie is incorrect to do this."
In the end Laurie needs to be far more careful in her citation of Leventhall with him observing:
"I find it unwise to believe much of what Dr Laurie states, unless there is confirming evidence. She also misuses references, so that you have to be careful to check whether these are relevant and actually say what she claims they do."