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Posted: Mar 17, 2013
How the power of suggestion generates wind farm symptoms
(Nanowerk News) A surge in health complaints linked to wind farms could owe more to increased discussion of health risk than the low-level sound generated by the actual turbines, according to a new study.
Exposure to infrasound, at the level produced by wind turbines, is an ordinary occurrence.
Increased numbers of people reporting symptoms linked to turbines could be explained by public warnings about health effects triggering the complaints; a phenomenon known as the nocebo effect.
This occurs because such information can create health concerns and related symptom expectations, priming people to notice and negatively interpret common physical sensations and symptoms.
In an experimental study published this week in Health Psychology ("Can Expectations Produce Symptoms From Infrasound Associated With Wind Turbines?"), our experimental team tested the potential for information about the alleged health risks presented by wind farms to trigger symptoms reports.
Much of the conjecture about the health effects presented by wind turbines relates to the generation of sub-audible sound (infrasound), which is said to cause physical symptoms such as headache, nausea, fatigue and ear pressure. However, exposure to infrasound, at the level produced by wind turbines, is an ordinary occurrence. Infrasound is consistently present in the environment caused by natural phenomena, such as air turbulence and ocean waves; by machinery, such as air conditioners; and is produced within the body, by processes such as respiration.
In this study, we exposed 60 participants to ten minutes of infrasound and ten minutes of sham infrasound (silence), within a listening room designed for subjective listening experiments. Prior to the listening sessions, half of the participants (high expectancy participants) watched a DVD presentation which contained television footage, available on the internet, in which people living in the vicinity of wind farms recounted their experience of symptoms that they believed to be caused by wind farms.
The remaining participants (low expectancy participants) viewed a DVD in which experts put forth the scientific position that exposure to infrasound generated by wind turbines would not cause symptoms. Before and during each ten-minute exposure session participants rated their experience of 24 physical symptoms, such as dizziness, ear pressure, and headache.
Results showed there were no symptomatic changes before or during exposure periods in the low expectancy group. However, participants in the high expectancy group reported significant increases from pre-exposure assessment in the number and intensity of symptoms reported during exposure periods. This increase was the same whether exposure was to infrasound or to sham infrasound, indicating that exposure to infrasound did not add to the symptomatic experience.
Further, during both exposure periods, high expectancy participants reported more symptoms they had been told were typical of infrasound exposure, rather than symptoms they were informed were atypical.
The findings indicate that negative health information readily available to people living in the vicinity of wind farms has the potential to create symptom expectations, providing a possible pathway for symptoms attributed to operating wind turbines. This may have wide-reaching implications. If symptom expectations are the root cause of symptom reporting, answering calls to increase minimum wind-farm set back distances is likely to do little to assuage health complaints.
Ironically, discussion within the community about the alleged health effects of wind-farms may trigger the very symptoms about which residents are concerned. If this is the case, media coverage of the wind-farm debate must be balanced, so that undue emphasis is not placed on purported health risk.