Over the weekend, the UK papers broke the story that government officials suppressed the findings of a 2006 study on wind turbine noise and its effects on nearby residents.
The study, prepared by acoustics noise and vibration consultants Hayes McKenzie Partnership (HMP), was used to support the position that existing Government wind farm noise guidelines from 1996 were adequate and that turbine noise posed no health risks for neighboring dwellings. However, draft versions of the document obtained by Mr. Mike Hulme of the Den Brook Judicial Review Group revealed that the final published report removed earlier recommendations that stated:
1. night time wind turbine noise limits should be reduced from 43dB to 38dB, and,
2. in the event that the turbine noise has a discernible beating character, the limit should be further reduced to 33dB.
These newly revealed recommendations are consistent with the World Health Organization's ("WHO") guidelines for nighttime noise levels published in October which state:
"Based on the systematic review of evidence produced by epidemiological and experimental studies, the relationship between night noise exposure and health effects can be summarized here . Below the level of 30 dB, no effects on sleep are observed except for a slight increase in the frequency of body movements during sleep due to night noise. There is no sufficient evidence that the biological effects observed at the level below 40 dB are harmful to health. However, adverse health effects are observed at the level above 40 dB, such as self-reported sleep disturbance, environmental insomnia, and increased use of somnifacient drugs and sedatives. Therefore, 40 dB is equivalent to the lowest observed adverse effect level (LOAEL) for night noise."
We note that wind developers typically advocate for noise limits at project sites ranging between 45 and 55 dB as measured at night at the outside wall of nearby homes -- well above WHO guidelines.
Despite these recommendations, a new report funded by the Canadian (CANwea) and American Wind Energy Associations (AWEA) has concluded that noise and vibrations emitted by industrial wind turbines may be annoying but pose no risk to human health. It further states that "allegations of adverse health effects from wind turbines are as yet unproven." The expert panel that compiled the report also agreed that "the number and uncontrolled nature of existing case reports of adverse health effects alleged to be associated with wind turbines are insufficient to advocate for funding further studies."
It may be that adverse health effects due to proximity to wind turbines is not yet proven but to turn a blind eye to testimonials now pouring in from across the United States, Canada, Australia, New Zealand, Europe and Asia is unimaginable. We are reminded of the assertions made by the cigarette industry in the 1950's when reports surfaced that smoking could lead to lung cancer, including the quote used in the title of the article, "We believe the products we make are not injurious to health."
Interestingly, David M. Lipscomb PhD, one of the experts who contributed to the CANwea and AWEA report held a very different view of noise induced annoyance in June 2000 in his testimony before the State of Washington Energy Facility Site Evaluation Council on a proposed electric generating facility.
When asked at what sound levels he would expect to see reactions of effects of noise he stated:
"Surprisingly small sound levels can cause certain reactions. For example, sleep studies have shown that subjects will shift two or three levels of sleep when the environmental sound is increased only 5 dB. Thus, a person in the Rapid Eye Movement (REM), the fifth stage of sleep, when the bedroom sound level is 35 dBA, will shift out of that essential level of sleep when the sound increases only to about 40 dBA. As a result, this negative health effect is known to lead to chronic fatigue and irritability."
The question of noise is front and center in the minds of most who are being asked to consider a wind plant in their community. And the wind industry's insistence on dismissing the issue is proving a losing strategy. This most recent report, coming on the heels of the WHO's guidelines and revelations of suppressed documents in the UK, is further proof that the industry prefers to manipulate public impression than act responsibly. As with the cigarette industry, the preponderance of evidence will become undeniable.
 dB refers to Lnight,outside, the night-time noise indicator (Lnight): the A-weighted long-term average sound level as defined in ISO 1996-2:1987, determined over all the night periods of a year.