What’s next, a Senate inquiry into infrasound from trees, waves or air conditioners?

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At the centre of claims about wind farms allegedly causing health problems is the infrasound that wind turbines generate as they turn in the wind.

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Infrasound is generated by wind turbines, air conditioners, and a host of natural phenomena. Johan Swanepoel/Shutterstock
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The Conversation

Infrasound is generated by wind turbines, air conditioners, and a host of natural phenomena. Johan Swanepoel/Shutterstock
Infrasound is generated by wind turbines, air conditioners, and a host of natural phenomena. Johan Swanepoel/Shutterstock

At the centre of claims about wind farms allegedly causing health problems is the infrasound that wind turbines generate as they turn in the wind.

Infrasound is sound below 20Hz, which is generally inaudible. Wind turbines are just one source of artificial man-made infrasound. Others include power stations, industry generally, motor vehicle engines, compressors, aircraft, ventilation and air conditioning units, and loudspeaker systems. Everyone living in an urban environment is bathed in infrasound for most of their lives.

As I sit at my inner Sydney desk writing this I’m copping infrasound from the planes that pass some 200-300 metres over my house sometimes many times an hour, the sound of passing road traffic on a quite busy road 100 metres from our house, and the stereo system I listen to as I write. Don’t tell anyone, but I feel fine and I’ve lived here 25 years.

But infrasound is generated by natural phenomena too. These include rare occurrences such as volcanoes and earthquakes, but also sources like ocean waves and air turbulence (wind) that countless millions, if not billions, are exposed to on most days. Anyone living close to the sea is surrounded by constant infrasound from waves.

The inclusion of wind as a source of infrasound is of particular significance to claims made that wind turbine-generated infrasound is noxious. In a Polish research paper published in 2014, the authors set out to measure infrasound from wind turbines and to compare that with naturally occurring infrasound from wind in trees near houses and from the sound of the sea in and around a house near the seaside.

The researchers used the average G-weighted level (LGeq) over the measurement period. This is the standardised measurement of infrasound which approximately follows the hearing threshold below 20Hz and cuts off sharply above 20Hz.

The infrasound levels recorded near 25 100-metre high wind turbines ranged from 66.9 to 88.8 LGeq across different recordings. Those recording infrasound in noise from wind in a forest near houses ranged from 59.1- 87.8 LGeq. The recordings of sea noise near seaside houses ranged from 64.3 to 89.1 LGeq. These infrasound levels were thus very similar cross the three locations.

The peak 88.8 LGeq was recorded very close to the turbines – virtually directly under the blades. The lower 66.9LGeq was 500m away, which is more like a common scenario for the nearest residences to turbines. Similarly, for the other sources, highest levels were nearest the source.

Wind is, of course, a prerequisite for wind turbines to turn and generate their mechanical infrasound. Here, the Polish authors noted that:

natural noise sources … always accompany the work of wind turbines and in such cases they constitute an acoustic background, impossible to eliminate during noise measurement of wind turbines.

This is a fundamentally important insight: wherever there are wind turbines generating infrasound, there is also wind itself generating infrasound. And it is impossible to disentangle the two. Indeed, every time I’ve been near wind turbines, easily the most dominant sound has been that of the wind buffeting my ears.

In 2013, the South Australian Environmental Protection Authority measured infrasound in a variety of urban and rural settings. With the latter, this included locations near and well away from wind farms.

They reported that in urban settings, measured infrasound ranged between 60-70 decibels. In fact, at two locations – the EPA’s own offices and an office with a low frequency noise complaint – building air conditioning systems were identified as significant sources of infrasound. These locations exhibited some of the highest levels of infrasound measured during the study.

They concluded:

This study concludes that the level of infrasound at houses near the wind turbines assessed is no greater than that experienced in other urban and rural environments, and that the contribution of wind turbines to the measured infrasound levels is insignificant in comparison with the background level of infrasound in the environment.

Wind farm opponents claim infrasound is the cause of this Old Testament-like plague of plagues (now numbering 244 different problems). If that were true, how is it that hundreds of thousands of Australians who are daily exposed to infrasound in cities, in their houses surrounded by dastardly infrasound-generating fans, air conditioners and stereo systems, and those who live near trees or the sound of the ocean aren’t breaking down the door of those sworn enemies of infrasound Senators John Madigan, Nick Xenophon, Chris Back, David Leyonhjelm and Bob Day who brought us their scathing report on wind farms in June?

The explanation lies in factors we recognise frequently in risk-perception studies, popularised by Peter Sandman. Sandman has produced matrices of factors which have been often found to be associated with increased levels of community “outrage” about putative environmental threats to health.

Sandman distinguishes primary from additional factors, with primary factors being those which have been shown to be more strongly associated with increased levels of community concern.

I applied these to a case study of mobile phone tower complaints in the 1990s. I’ve now constructed the table below indicating the likely applicability of these factors to the case of predicting community worry about wind farms.

People don’t worry about infrasound in wind, trees and ocean waves because these sources are natural, while the same levels of infrasound from wind turbines are considered quite differently as they are sourced from what anti-wind farm activists like to call evil “industrial” wind farms.

The rare examples of people complaining who host wind turbines on their land for rental payment, compared with the far more common situation of non-hosting neighbours complaining, illustrates the voluntary vs coerced exposure factor, as well as the fair vs unfair factor. Those not benefiting from lucrative rental payments because of unsuitable local topography, while near neighbours can, understandably feel this as unfair.

Wind turbines are very memorable and exotic (a new experience to many), while wind in trees or the pounding of the ocean is very familiar and unremarkable, both factors likely to greatly diminish concerns.

Table: Primary and additional components predicting community outrage about putative environmental risks to health: the case of wind turbines. (two ticks = applies strongly to wind turbines; one tick = likely to apply less strongly)

 

The 2015 Senate (majority) report into wind farms roundly rejected the idea that psychosocial factors such as nocebo effects were largely responsible for the challenging historical and geographical variance in wind farm complaints. A nocebo effect is the opposite to a placebo effect: instead of exposure to an inactive agent making people feel better because of belief that it will, nocebo effects are when a benign agent makes people feel worse because they have been told it will.

The Committee, chaired by avowed wind farm opponent John Madigan, was emphatic that infrasound was the culprit but did not produce convincing evidence for this.

If the committee is sincere in its concerns about the health effects of infrasound, will we soon learn of a new inquiry about the pernicious and unappreciated dangers of living near the sea or trees, having air conditioners, stereos, ceiling fans, or travelling in motor vehicles?

Source: The Conversation. Reproduced with permission.

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11 Comments
  1. Beat Odermatt 4 years ago

    Australia’s bunch of anti-wind senators are like the ticks on the tits of a bull, of little use but an ongoing nuisance.

    • phred01 4 years ago

      comedian ha ha ha ha !

      • Beat Odermatt 4 years ago

        Yes, these senators are comedians, but sadly they are paid a fortune to act like idiots. I cannot respect selfish drongos trying to pretend to do something for the common good. These senators are selfish, narrow minded people with a massive ago. They are not funny.

  2. Chris Fraser 4 years ago

    The Senators must be so scratching their heads trying trying to work out how to be annoyed by infrasound.

    • phred01 4 years ago

      Plenty of infrasound is generated in the big house

    • Beat Odermatt 4 years ago

      Instead listening to a mad money chasing minority they would better off listening to independent scientists. I am sick and tired watching these senators chasing headlines by fighting against a good environment. They should be ashamed!

  3. John Saint-Smith 4 years ago

    Another under-appreciated danger of wind turbines is caused by people telling these alleged sufferers that they are imagining it. The cognitive dissonance tends to generate even more headaches. The worst thing we can do is demonstrate conclusively that their fears about infrasound are utterly delusional – when they are believe that the turbines have been turned off, and announce that they’ve had the first decent night’s sleep in months, only to be informed that unbeknown to them, the turbines have been spinning out ‘maddening’ ultrasound as usual – that is likely to unleash full-blown paranoid psychosis.

    • phred01 4 years ago

      It like EM fields from Hi voltage power lines. People swear that thy are affected but the problem vanishes if the power lines are buried. Whether the lines in the air or buried the EM 50hz fields are the same. The only difference is when buried there is no visual impact

  4. MaxG 4 years ago

    I am surprised about the BS artists in this country… and how the money can be found to support this nonsense… while public utilities need to be privatised and services cut.

  5. Miles Harding 4 years ago

    Another factor may be fear and symbolism.

    I meet Lomborg adherents from time to time and they seem receptive to a message that says “Yes, the climate is changing, but there’s no need to worry or do anything about it”, but then along comes this wind farm, which is one of the most obvious signs of ‘doing something’.

    As for these anti-wind senators, they are no more dishonest or delusional than the Abbott government that inspired them. None seem to realise that they are playing politics with nature, a nature that does not hear political arguments.

    Perhaps, these senators could be isolated from all forms of infrasound by putting them in a vacuum. 🙂

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