Wednesday, December 16, 2009

Wind Turbine Sound and Health Effects

In contrast to the latest effort by the Canadian and American Wind Energy Associations to assert otherwise ("Wind Turbine Sound and Health Effects: An Expert Panel Review" (December 2009), read what a couple members of their expert panel said before they tapped into the wind industry money pipeline.

1. "A Review of Published Research on Low Frequency Noise and Its Effects", Report for Department for Environment, Food and Rural Affairs (U.K.) by Dr Geoff Leventhall, assisted by Dr Peter Pelmear and Dr Stephen Benton, May 2003 [excerpts]

8. Annoyance

8.2.4 Annoyance and the dBA. A comparison of a band of noise peaking at 250Hz with a band peaking at 100Hz, whilst both were adjusted to the same A-weighted level, showed that the annoyance from the low frequency noise was greater than that from the higher frequency noise at the same A-weighted level (Persson et al., 1985). This work was subsequently extended (Persson and Bjorkman, 1988; Persson et al., 1990) using a wider range of noises, for example, peaking at 80Hz, 250Hz. 500Hz and 1000Hz, leading to the following conclusions:

There is a large variability between subjects.

The dBA underestimates annoyance for frequencies below about 200Hz.


10. Low frequency noise and stress

10.1 Low frequency noise and cortisol secretion. It is difficult to measure stress directly, but cortisol secretion has been used as a stress indicator (Ising and Ising, 2002; Persson-Waye et al., 2002; Persson-Waye et al., 2003). Under normal circumstances, cortisol levels follow a distinct circadian pattern in which the diurnal variation of cortisol is to drop to very low levels during the early morning sleep period, rising towards the awakening time. The rise continues until about 30 minutes after awakening, followed by a fall until midday and further fluctuations. Stress disrupts the normal cortisol pattern.

Ising and Ising (2002) discuss how noise, perceived as a threat , stimulates release of cortisol. This also occurs during sleep, thus increasing the level of night cortisol, which may interrupt recreative and other qualities of sleep. Measurements were made of the effect on children who, because of traffic changes, had become exposed to a high level of night lorry noise. There were two groups of subjects, exposed to high and low noise levels. The indoor noise spectrum for high levels typically peaked at around 60Hz, at 65dB, with a difference of maximum LC and LA of 26dB. The difference of average levels was 25dB, thus indicating a low frequency noise problem. Children exposed to the higher noise levels in the sample had significantly more problems with concentration, memory and sleep and also had higher cortisol secretions. Conclusions of the work were that the A-weighting is inadequate and that safer limits are needed for low frequency noise at night.

Perrson Waye et al (2003), studied the effect on sleep quality and wakening of traffic noise ( 35dB LAeq, 50dB LAmax) and low frequency noise (40dB LAeq). The low frequency noise peaked at 50Hz with a level of 70dB. In addition to cortisol determinations from saliva samples, the subjects completed questionnaires on their quality of sleep, relaxation and social inclinations. The main findings of the study were that levels of the cortisol awakening response were depressed after exposure to low frequency noise and that this was associated with tiredness and a negative mood.

In a laboratory study of noise sensitive subjects performing work tasks, it was found that enhanced salivary cortisol levels were produced by exposure to low frequency noise (Persson-Waye et al., 2002). A finding was that subjects who were sensitive to low frequency noise generally maintained higher cortisol levels and also had impaired performance. A hypothesis from the study is that changes in cortisol levels, such as produced by low frequency noise, may have a negative influence on health, heightened by chronic noise exposure. The three studies reviewed above show how low frequency noise disturbs the normal cortisol pattern during night, awakening and daytime exposure. The disturbances are associated with stress related effects.

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Related to this is the finding from a Dutch study released last year that: "the sound of wind turbines causes relatively much annoyance. The sound is perceived at relatively low levels and is thought to be more annoying than equally loud air or road traffic" ("Visual and acoustic impact of wind turbine farms on residents", by Frits van den Berg, Eja Pedersen, Jelte Bouma, and Roel Bakker, June 3, 2008). This was the final report of the European Union–financed WINDFARMperception study. It is not cited in the new CanWEA/AWEA paper. See also a note from September that in this study, only 9% of the respondents lived with estimated outdoor noise level from wind turbines of more than 45 dBA. It is also noted that in an oft-cited (including in this latest CanWEA/AWEA work) Swedish study (Pedersen and Persson Waye, 2007), the average outdoor noise level was only 33.4 ± 3.0 dBA and the average distance to the nearest wind turbine, which could be as small as 500 kW in size, was 2,559 ± 764 ft (780 ± 233 m) -- the finding of few health effects is hardly relevant to the common North American situation of much closer construction of much much larger machines; in fact, the findings of significant annoyance and sleep disturbance (both of which have adverse health effects) under such "amenable" conditions should ring alarm bells about giant erections closer to homes, not to mention their effect on wildlife.
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13. General Review of Effects of Low Frequency Noise on Health

13.2 Effects on humans. Infrasound exposure is ubiquitous in modern life. It is generated by natural sources such as earthquakes and wind. It is common in urban environments, and as an emission from many artificial sources: automobiles, rail traffic, aircraft, industrial machinery, artillery and mining explosions, air movement machinery including wind turbines [emphasis added], compressors, and ventilation or air-conditioning units, household appliances such as washing machines, and some therapeutic devices. The effects of infrasound or low frequency noise are of particular concern because of its pervasiveness due to numerous sources, efficient propagation, and reduced efficiency of many structures (dwellings, walls, and hearing protection) in attenuating low-frequency noise compared with other noise.

13.6 Conclusion. There is no doubt [emphasis added] that some humans exposed to infrasound experience abnormal ear, CNS, and resonance induced symptoms that are real and stressful. If this is not recognised by investigators or their treating physicians, and properly addressed with understanding and sympathy, a psychological reaction will follow and the patientís problems will be compounded. Most subjects may be reassured that there will be no serious consequences to their health from infrasound exposure and if further exposure is avoided they may expect to become symptom free.

2. "Application of Sumas Energy 2 Generation Facility: Prefiled Testimony of David M. Lipscomb, Ph.D., Before the State of Washington Energy Facility Site Evaluation Council", June 2000 [excerpt]

Q: Are you familiar with the effects of noise on public health?

Ans: Yes. In addition to my work with the U. S. EPA, I have attended and made presentations to numerous International Congresses on Noise as a Public Health Problem. They include 1968 (Washington, D.C.); 1973 (Dubrovnic, Yugoslavia); 1978 (Friburg, Germany) and 1982 (Turin, Italy). These were gatherings of active researchers on the topic from around the world. Proceedings of the Congresses were produced and are contained in my library.

Q: Could you describe some of these effects?

Ans: Yes. The effects include loss of sleep, hearing damage, irritability, exacerbation of nervous and cardiovascular disorders, and frustration stemming from loss of control of one’s acoustical environment.

Q: Is a person able to control the physical reaction within their body to sound?

Ans: Only to a limited extent. Dr. Samuel Rosen, formerly physician at New York City’s Mt. Sinai Hospital stated: “You may be able to ignore noise – but your body will never forgive you.” The truth in this statement is that “coping” is a fatiguing activity. Therefore, the energy spent in coping with environmental noise or the frustrations it produces, is robbed from energy desired for other forms of activity.

Q: At what sound levels would your expect to see reactions of effects of noise?

Ans: 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.

Q: Could you please explain the effect of noise at night in residential areas?

Ans: Yes, recall that I mentioned low-frequency noise entering a house almost unimpeded. If that noise source is the predominant sound in a bedroom, any change in the sound level can influence a person’s sleep level, therefore, reducing the adequacy of rest afforded by sleep. Further, the noise source, if it is from the power generation plant, serves as a masking noise. That is, it covers up other sounds to which one may need to attend. For example, sounds from a child’s bedroom.

Q: Could you please explain the effect of low frequency noise and how it travels?

Ans: Yes, but to do so, I must introduce the term “wave length”. This is the distance covered by a sound during one cycle. For example, a mid-frequency 1000 Hz sound has a wave length of slightly more than 1-foot. Lower frequency sounds have longer wave lengths. Thus, a 100 Hz sound has slightly more than a 10-foot wave length. The longer the wave length, the more efficient the sound is in penetrating barriers such as walls of a structure. For the purposes of this investigation, I would define low frequency sounds as those falling below 100 Hz. Perhaps you have experienced life in an apartment when a neighbor plays a stereo loudly. The sound that penetrated to your quarters was the bass (low frequency sound). Also due to the wave length characteristics, low frequency sounds dissipate less over distance than do sounds of higher frequency.

wind power, wind energy, wind turbines, wind farms, environment, environmentalism, human rights, animal rights, anarchism, ecoanarchism, anarchosyndicalism