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Expectation influences reporting of adverse health effects from wind farms -

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Robyn Williams: And so to wind, wind turbines. Some deplore them for health reasons. Now yet another study has found no reason to blame them. Our PhD this week is Fiona Crichton from the University of Auckland.

Fiona Crichton: In recent years a small number of people have reported the experience of a cluster of physical symptoms, such as headaches, dizziness, and fatigue, which they attribute to exposure to sound from wind farms, particularly sub-audible sound known as infrasound. However, there have been over 60 studies investigating the association between wind farms and human health, and the weight of scientific evidence does not support a direct link between reports of adverse health effects and exposure to sound from wind farms. In fact the pattern of health complaints across the world reveals that symptom reporting is relatively rare, and tends to occur in areas where there has been targeted negative publicity about wind turbines, or where people are accessing negative health information about wind farms.

Since 2009, claims that wind farm sound, particularly infrasound, causes health effects have proliferated through the media and the internet. This occurs even though exposure to sub-audible infrasound is a consistent and normal human experience. Infrasound is produced by natural phenomena such as the wind and ocean waves, as well as by machinery such as traffic, and by internal physiological processes such as respiration and heart-beat. Misinformation that exposure to a benign agent may cause health problems, can trigger symptom reporting in the presence of that agent via the nocebo effect. The nocebo effect occurs when the expectation of adverse health effects leads to increased symptom reporting.

That nocebo responses might be providing a pathway for symptom reporting in the case of wind farms is supported by a sham controlled study we conducted in the Acoustic Research Centre at the University of Auckland. In this study, participants were exposed to separate periods of sub-audible infrasound, and sham infrasound (actually silence), although they were led to believe they would be exposed to infrasound during both exposure periods. Participants were randomised into high or low expectancy groups. Prior to exposure, high expectancy participants watched a DVD containing extracts from the internet outlining that infrasound generated by wind turbines had triggered adverse health effects in some wind farm residents. Conversely, low expectancy participants watched a DVD explaining the scientific position, that exposure to wind farm generated infrasound would not cause symptoms. Results showed that high expectancy participants reported a significant increase in the number and intensity of their symptoms during exposure to both infrasound and to silence, while there was no change in symptom reporting in the low expectancy group during either exposure period.

Building on these findings we conducted a series of experimental studies in which participants were simultaneously exposed to audible wind farm sound (recorded 1km from a wind farm) and sub-audible infrasound. It was a consistent finding across experiments that participants accessing media health warnings about the purported adverse health effects of wind farm sound exposure reported increased noise annoyance and symptoms in the presence of wind farm sound. We also found that providing participants with internet information about the possible therapeutic effects of infrasound exposure, led to reduced annoyance and symptom reporting during sound exposure. Thus expectations were shown to have a determinative effect on the experience of wind farm sound, in both positive and negative directions.

Critically, we discovered it is possible to reverse negative expectations after they are formed and thereby alleviate annoyance and symptom complaints during exposure to wind farm sound. This is important information if we are to address health complaints in the community. Results showed that nocebo responses were reversed when participants were provided an alternative positive health narrative about wind farm sound, whereby infrasound was depicted as a normal component of environmental sound, and reference was made to the current use of infrasound in therapeutic contexts. We also found nocebo responses could be reversed by explaining to participants that their symptomatic experiences were prompted by expectations formed from the internet material they had watched. This nocebo explanation was designed to normalise the nocebo response, to be reassuring, and to eliminate blame.

Brain imaging studies reveal that symptoms experienced as a result of nocebo responses are authentic experiences. Thus reversing negative expectations about wind farms is likely to be a vital strategy to address genuine suffering in wind farm communities. Analyses conducted across experiments revealed that changes in symptom reporting and annoyance reactions, in both positive and negative directions, were explained by changes in anxiety. This highlights the need for responsible and careful framing of messages about wind farms that minimise anxiety and reduce the potential for the creation of symptom expectations. Importantly, experimental findings suggest that creating more positive expectations about wind farm sound may ameliorate health complaints and reduce annoyance reactions in community settings.

Robyn Williams: Fiona Crichton and her PhD at the University of Auckland.