Is the infrasound of wind farms
causing adverse health effects?
Valtteri Hongisto
senior research scientist
group leader of indoor environment research group
[email protected]
+358 40 5851 888
Turku University of Applied Sciences - TUAS
Vaasa 26 January 2017
1
Wind turbine related
activities in TUAS
Consultation services
• Noise measurements indoors
and outdoors
• long-term and short-term
Noise propagation modeling
Questionnaire surveys
Sound insulation measurement
Professional role in various
kinds of events
• Etc.
• Paid by: Companies,
municipalities, etc.
•
•
•
•
Education in TUAS
• Envidonmental acoustics
Independent public research
• ANOJANSSI project investigates the how the
environmental noise should be measured to reflect noise
annoyance
• WP2: Laboratory experiments to determine the penalty
needed for specific noise features
• tonality
• amplitude modulation
• spectrum / low frequency noise
• impulsiveness
• WP3: Socio-acoustic surveys in residential buildings
exposed to
•
•
•
•
•
•
•
•
wind turbine noise
rock crushing noise
road traffic noise
power plant noise
WP5: Sound insulation of facades under 200 Hz
Infrasound is beyond the scope except in WP5
Project timetable: 2016-2018
Funding: Tekes (60%), University, 2 ministries, companies
2
Hongisto 2014 Finnish Institute of Occupational Health
A
B
8000
4000
2000
Taajuus [Hz]
1000
500
250
125
63
31.5
B
16
• Because of ISO 226, sounds under 20 Hz are
defined as infrasounds.
• This is probably the main reason for the
false general apprehension that infrasounds
are inaudible.
• False information is continuously teached in
all school levels, in Wikipedia, also in
Universities.
A
8
• 68% of population lie within ±6 dB from the
median
• People over 50 years have 7 dB higher hearing
threshold below 200 Hz than young people
130
120
110
100
90
80
70
60
50
40
30
20
10
0
-10
4
• ISO 226 hearing threshold only down to 20
Hz.
• However, many experiments have published
hearing thresholds under 20 Hz.
Kuulokynnystaso LpZ [dB]
2
What is infrasound
Möller and Pedersen (2004)
ISO 226:2003
Wanatabe and Möller (1990)
3
Inaudible infrasound?
• The definition of infrasound is
unfortunate: the definition should
concern the area A – inaudible
sounds under hearing threshold.
• If the citizens believe that
infrasounds might have adverse
health effects, it is expected those
effects appear irrespective of the
dB level of infrasound because
general apprehension is that
infrasounds are always inaudible.
Sound pressure level, LpZ [dB]
170
160
150
140
130
120
infrasound
110
limit 20 Hz
100
90
80
70
60
50
40
30
20
10
0
C
B
A
Frequency [Hz]
Threshold of hearing
Threshold of pain
A Non-audible sound
B Audible sound
C Pain
4
Amplitude modulation, AM
Spectrum of sound
60
Momentary level
Mean level
Silent level
Loudest level
46
Loudest level
50
Linear sound pressure level[dB]
• pulsating nature
• the frequency of AM is typically
0.7 Hz which belongs to the
infrasound range
48
Mean level
• Compare: back and forth
movement of volume button
• AM of wind turbines is often
erroneously believed to be the
infrasound source:
Level as a function of time
Silent level
44
Hearing threshold
40
30
20
A--weighted sound level [dB]
• Wind turbine (WT) noise has
AM nature, i.e. periodic
variation of sound level
42
40
38
36
34
32
10
period 1.5 s
frequency 0.67 Hz
30
Hongisto 2014 Finnish Institute of Occupational Health
Frequency [Hz]
8000
4000
2000
1000
500
250
125
63
31.5
0
28
0
1
2
3
Time [s]
5
Sources of infrasound
Inaudible (<100 dB)
• Respiration, heart beat
• Running, coughing
• Swinging
• Walking on the floor
• Sling of washing machine
• Large waterfalls
• Sea waves
• Pressure changes in the
athmosphere
• Air flow of ventilation
• Fans and engines
• Traffic
• Many industrial processes,
including wind turbines
Audible (>100 dB)
• Explosion
• Thunder
• Strong wind
• up to 135 dB at 100 km/h; up
to 110 dB at 25 km/h),
• Idle sound of large diesel
engines in trucks, busses
and vessels
• Opening the back window
of the car in motorway
• LEXUS 123 dB at 17 Hz (FFT)
• Swimming
Leventhall 2007 Progr Biophys Molecular Biol
Crichton et al 2013 Front Publi Health
6
Infrasound levels of wind turbines, 1
• 29 wind farms were investigated
• 164 points within 100 and 1000 m
were measured
• 5 days were measured in each point
• 1-3 MW turbines
Main outcomes:
• Hearing threshold level was not
exceeded below 31 Hz
• Infrasound levels 20 dB below
hearing threshold
JAPANESE STUDY: Tachibana et al. 2014 Noise Con Eng J
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Infrasound levels of wind turbines, 2
• Literature survey of 18 different
turbines, 0.05-4.2 MW
• Turbines with downwind oriented
rotors produce 10-30 dB higher
infrasound levels than upwind
oriented rotors of the same output
power.
• Downwind turbines are very seldom
used onshore nowadays.
• Main outcome: Infrasound of upwind
turbines could be neglegted at typical
living distances because the levels are
far below hearing threshold.
DANISH STUDY:
Jacobsen 2005 J Low Freq Noise Vibr Act Con
8
Infrasound
levels of
WTʼs - 3
• Report suggests that we are exposed to larger infrasound
levels than those produced by WTʼs in our normal life.
9
Wind turbine syndrome WTS
• Pierpont (2009) interviewed 38 persons from 10
families living nearby wind farm
• The results were published in a book by herself
• scientifically invaluable
• no control group living far from the farm
• selection bias is possible
• Pierpont found similar symptoms among the
persons and created the name WTS
• Infrasound of WTʼs was said to cause the WTS
• Scientific epidemiological evidence is lacking to
prove a causal link between WTʼs infrasound and
VAD. Therefore, CD-10 does not recognize WTS
Some symptoms of WTS:
• sleep disturbance,
• headache
• tinnitus (ringing in ears)
• ear pressure
• dizziness
• vertigo
• nausea
• visual blurring
• tachycardia (rapid
• heart rate)
• irritability
• problems with concentration memory • panic episodes
• International Statistical Classification of Diseases and Related Health Problems
• The non-specific symptoms are typical among the
whole population (non-specific symptoms)
• Non-specific symtoms are typical to hypochondria.
• The WTS has become a very popular reason to
oppose WTʼs s after 2009 at least in Australia.
Knopper & Ollson et al. 2011 Env Health
10
Vibroacoustic disease, VAD
• VAD was originally suggested from a
study involving aircraft technicians
who were exposed to very loud low
frequency noise in the long term
(Castelo Branco&Alves Pereira)
• Alves-Pereira and Castelo Branco
(2007) suggested that living in the
proximity of wind turbines could also
lead to the development of VAD
• However, ICD-10 does not recognize
WTS
Castelo Branco 1999 Aviat Space Environ Med
Castelo Branco&Alves Pereira 2004 Noise Health
• Chapman and George (2013) showed
that VAD has become a real factoid , i.e.
a false or spurious statement
presented as a fact, perhaps because of
a strong distribution of the hypothesis in
scientific congresses and internet in free
access form.
• Internet search showed 36 papers
dealing with VAD and wind turbines.
Thirty-five (35) of them were authored
either by Alves-Pereira or Castelo Branco.
• 74% of citations to their papers were selfcitations. Median self-citation rate is 7%.
Chapman and George (2013, Australian and New Zealand Journal of Public Health)
11
Health effects of wind turbine noise
• A critical review of 1231 publications
was done based on search keywords:
• wind turbines or wind farms, health,
noise, annoyance, tinnitus, vertigo,
epilepsy, headache
• 36 of them addressed specific healthrelated outcomes in relation to WT
noise exposure
• No evidence indicating an association
between WT noise exposure and
tinnitus, hearing loss, vertigo or
headache.
Schmidt and Klokker 2014 Plos One
• It is well-known that traffic noise
exposure may increase the risk of
cardiovascular disease and diabetes.
• The mechanism here could be
increased stress and reduced quality
of sleep, which can increase the risk of
abovementioned diseases.
• It has not been shown YET that wind
turbines could result in identical
health effects.
• However, the possibility of effects
cannot be ruled out !
• Thus, more research is needed in field
settings.
12
Outer hair cells
• Salt and Hullar (2010, Hear Res)
suggested that cochlearʼs outer hair cells
of the ear might have a higher sensitivity
to infrasound
• I.e. reactions to infrasound could be
detected under the hearing threshold
• The suggestion was based on animal
studies (guinea pigs).
• Confirming evidence has not been found
with human data.
13
FMRI
Dommes et al. 2009 Brain Res
Bauer et al. 2015 ICSV Italy
• Functional magnetic resonance imaging is increasingly used to reveal the brain responses to various
kind of stimuli
• Effects of infrasound have been studied recently.
• The studies have not shown brain responses at levels under the hearing threshold.
• Thus, the FMRI responses found with infrasounds may have occurred as a consequence of hearing
response.
• There is very little evidence that adverse brain responses could occur without simultaneous hearing
perception.
14
Canadian study on stress effects of WTN
• 1242 people living close to wind farms
participated in a cross-sectional survey at
various WT noise exposure levels
•
•
•
•
•
•
LEVEL
< 25 dB LAeq:
25-30 dB LAeq:
30-35 dB LAeq :
35-40 dB LAeq :
40-46 dB LAeq :
N
84
95
304
521
234
• Subjective measures (N=1242)
• Perceived stress
• Various other control variables
• Objective measures (N>600)
• Blood pressures in rest
• Heart rate in rest
• Long-term accumulation of stress hormones
(cortisol in hair)
• The findings did not support
an association between
noise exposure level and
stress of any kind
• Noise exposure level is
strongly associated with
infrasound level because the
attenuation is similar for noise
and infrasound.
• Because health effects were
not increased closer to the
turbines, infrasounds or any
other factor, might not cause
health effects according to this
study.
Michaud et al 2016 J Acoust Soc Am
15
%HA inside
100
Concern about health effects
Janssen et al. 2011
80
Hongisto et al 2015
70
• We investigated residentsʼ reactions
living within 2 km of a wind farm (Ii
Olhava, Pori Peittoo)
60
50
40
30
• Noise annoyance increased clearly
above 40 dB LAeq.
20
10
• %HA is percentage of people
reporting high annoyance of WT noise
• Concerns about health effects of WT
noise were strong among 15% of
population.
90
0
30
35
40
45
Noise level outside LAeq [dB]
Concerns about possible health effects of wind turbine noise
• The concerns were stronger
associated with noise annoyance
(R=0.50) than the noise level
(R=0.32).
Not at all
Only a little
To some extent
Very much
Hongisto et al 2015 Ympäristö & Terveys (in Finnish)
0%
20 % 40 % 60 % 80 % 100 %
% of responses
Extremely
much
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Nocebo effect
• So far, not a single scientific study provides
data which indicates a causal link between
infrasound of WTs and adverse health effects.
• Negative expectations and factoids related to
health effects of WTʼs infrasound are
increasingly distributed in the internet.
• Numerous high quality studies have shown
that negative expectations and beliefs towards
an environmental stressor can produce new
symptoms or strenghten the existing ones.
Placebo effect: positive
expectations can result in
positive outcomes.
Nocebo effect: negative
expectations can result in
negative outcomes.
• NOCEBO effect
Crichton et al 2014 Frontiers Publ Health
Salminen 2013 Lääkärilehti
17
Individuals have non‐specific symptoms
Possible
mechanism of
nocebo
Turbines are built
Non‐specific symptoms continue
False information that infrasound of WT’s impairs health
Sensitive individuals*
Anxious
ness
* Factors affecting
individual sensitivity
• Higher noise sensitivity
• More sensible hearing
• Negative attitudes
towards QTs
• Stress in life
• Visibility and audibility of WTs
• Low background level
• Certain personality
factors (Taylor et al. 2013)
Turbines are
audible & visible
Non‐sensitive individuals
Non‐specific symptoms continue
Nothing happens
Annoyance of noise & flicker
Sleep
disturbance
Health concerns
Increase of symptoms
PUBLIC REACTIONS
Complalnts
Real illnesses
Acts against WT’s
CONCLUSIONS
• Humans hear infrasounds, i.e. sounds under 20 Hz if the
level exceeds 90-120 dB.
• The infrasound level of wind turbines seems not to exceed
the hearing threshold.
• Infrasound of WTʼs is not particularly high compared to
other infrasound sources we are exposed to.
• Present evidence supports that
• hearing sensation precedes other health effects of noise.
• it is very improbable that infrasound of wind turbines could have
adverse health effects in living environments.
• Several scientific studies suggest that concerns and fears
based on false information may produce symptoms and
adverse health effects.
• Concern and stress caused by false information related to
adverse health effects of WT infrasounds can produce
health symptoms although the infrasound would not.
• Popular fact-based information should be distributed in
free access form in the internet by independent parties so
that the amount of fact documents exceeds the amount of
factoid information.
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