Health effects and wind turbines: A review of the literature
Loren D Knopper1* and Christopher A Ollson2
Knopper
and Ollson Environmental Health 2011, 10:78
http://www.ehjournal.net/content/10/1/78
Abstract
Background: Wind power has been
harnessed as a source of power around the world. Debate is ongoing with respect
to the relationship between reported health effects and wind turbines, specifically
in terms of audible and inaudible noise. As a result, minimum setback distances
have been established world-wide to reduce or avoid potential complaints from,
or potential effects to, people living in proximity to wind turbines. People
interested in this debate turn to two sources of information to make informed
decisions: scientific peer-reviewed studies published in scientific journals
and the popular literature and internet.
Methods: The purpose of this paper
is to review the peer-reviewed scientific literature, government agency
reports, and the most prominent information found in the popular literature.
Combinations of key words were entered into the Thomson Reuters Web of
KnowledgeSM and the internet search engine Google. The review was conducted in the
spirit of the evaluation process outlined in the Cochrane Handbook for
Systematic Reviews of Interventions.
Results: Conclusions of the peer
reviewed literature differ in some ways from those in the popular literature.
In peer reviewed studies, wind turbine annoyance has been statistically
associated with wind turbine noise, but found to be more strongly related to
visual impact, attitude to wind turbines and sensitivity to noise. To date, no
peer reviewed articles demonstrate a direct causal link between people living
in proximity to modern wind turbines, the noise they emit and resulting
physiological health effects. If anything, reported health effects are likely
attributed to a number of environmental stressors that result in an
annoyed/stressed state in a segment of the population. In the popular literature,
self-reported health outcomes are related to distance from turbines and the
claim is made that infrasound is the causative factor for the reported effects,
even though sound pressure levels are not measured.
Conclusions: What both types of
studies have in common is the conclusion that wind turbines can be a source of annoyance
for some people. The difference between both types is the reason for annoyance.
While it is acknowledged that noise from wind turbines can be annoying to some
and associated with some reported health effects (e.g., sleep disturbance),
especially when found at sound pressure levels greater than 40 db(A), given
that annoyance appears to be more strongly related to visual cues and attitude
than to noise itself, self reported health effects of people living near wind
turbines are more likely attributed to physical manifestation from an annoyed state
than from wind turbines themselves. In other words, it appears that it is the
change in the environment that is associated with reported health effects and
not a turbine-specific variable like audible noise or infrasound. Regardless of
its cause, a certain level of annoyance in a population can be expected (as
with any number of projects that change the local environment) and the
acceptable level is a policy decision to be made by elected officials and their
government representatives where the benefits of wind power are weighted
against their cons. Assessing the effects of wind turbines on human health is
an emerging field and conducting further research into the effects of wind
turbines (and environmental changes) on human health, emotional and physical,
is warranted.
Keywords: Wind turbines, health,
annoyance, infrasound, sound pressure level, noise
Background
Wind
power has been identified as a clean renewable energy source that does not
contribute to global warming and is without known emissions or harmful wastes
[1]. Studies on public attitudes in Europe and Canada show strong support for the
implementation of wind power [2]. Indeed, wind power has become an integrated
part of provincial energy strategies across Canada; in Ontario, the Ontario
Power Authority has placed a great deal of emphasis on procuring what they term
“renewable and cleaner sources of electricity”, such as wind [3].
Although
wind power has been harnessed as a source of electricity for several decades
around the world, its widespread use
as a significant source of energy in Ontario is relatively recent. As with the
introduction of any new technology, concerns have been raised that wind power
projects could lead to impacts on human health. These concerns are related to
two primary issues: wind turbine design and infrastructure (i.e.,
electromagnetic frequencies from transmission lines, shadow flicker from rotor blades,
ice throw from rotor blades and structural failure) and wind turbine noise
(i.e., levels of audible noise [including low frequency noise] and infrasound).
If left unchecked and unmanaged, it is possible that individually or
cumulatively, these issues could lead to potential health impacts. In terms of
noise, high sound pressure levels (loudness) of audible noise and infrasound have
been associated with learning, sleep and cognitiv disruptions as
well as stress and anxiety [4-8].
As
a result, minimum setback distances have been established world-wide to reduce
or avoid potential effects for people living in proximity to wind turbines.
Under the Ontario Renewable Energy Approval (REA) Regulation (O. Reg. 359/09,
as amended by O. Reg. 521/10), a minimum setback distance of 550 m must exist
between the centre of the
base of the wind turbine and the nearest noise receptor (e.g., a building or
campground). This minimum setback distance was developed through noise modeling
under worst-case conditions to give a conservative estimate of the required
distance to attain a sound level of 40 dB(A) [9], the noise level that
corresponds to the WHO (Europe) night-noise guideline, a health-based limit value
“necessary to protect the public, including most of the vulnerable groups such
as children, the chronically ill and the elderly, from the adverse health
effects of night noise” [8]. Globally, rural residential noise limits are
generally set at 35 to 55 dB(A) [10].
This
paper focuses on the research involving landbased wind turbine projects. There
are several international off-shore marine projects that are in operation. There
was considerable interest in Ontario in developing off-shore wind projects on
the Great Lakes. However, in February, 2011 the Province announced that it would
not proceed with proposed offshore wind projects until further scientific research
is conducted http://www.news.ontario.ca/ene/n/2011/02/ontario-rules-out-offshore-wind-projects.html.
This does not appear to have been related, however, to health concerns.
Regardless,
debate is ongoing with respect to the relationship between reported health
effects and wind turbines, specifically in terms of audible and inaudible noise.
People interested in this debate tend to turn to two sources of information in
order to make decisions: scientific peer-reviewed studies published in
scientific journals, and the popular literature and internet. For the general public,
the latter sources are the most readily available and numerous websites have
been constructed by individuals or groups to support or oppose the development
of wind farms. Often these websites state the perceived impacts on, or benefits
to, human health to support the position of the individual or group. The
majority of information posted on these websites cannot be traced back to a
scientific peer-reviewed source and is typically anecdotal in nature. This
serves to spread misconceptions about the potential impacts of wind energy on
human health making it difficult for the general public (and scientists) to
ascertain which claims can be substantiated by scientific evidence.
Accordingly,
the purpose of this paper is to provide results of a review of the peer-reviewed
scientific literature and the most prominent information found in the popular literature.
We have selected this journal as the source of publication because it is a scientifically
credible journal with peer-reviewed articles that are easily accessible by the general
population who are interested in the subject of wind turbines and health effects.
Results of this review are used to draw conclusions about wind turbines and
health effects using a weight-of-evidence approach.
Methods
Peer-Reviewed
Literature
Publication of
scientific findings is the basis of scientific discourse, communication and
debate. The peer review process is considered a fundamental tenet of quality control
in scientific publishing. Once a research paper has been submitted to a journal
for publication it is reviewed by external independent experts in the field. The
experts review the validity, reliability and importance of the results and recommend
that the manuscript be accepted, revised or rejected. This process, though not perfect,
ensures that the methods employed and the findings of the research receive a
high level of scrutiny, such that an independent researcher could repeat the
experiment or calculation of results, prior to their publication. This process
seeks to ensure that the published research is of a high standard of quality,
accurate, can be reproduced and demonstrates academic/professional integrity.
In
order to assess peer-reviewed studies designed to test hypotheses about the
association between potential health effects in humans and wind turbines, a
review of the primary scientific literature was conducted. While our review did
not strictly follow the evaluation process outlined in the Cochrane Handbook
for Systematic Reviews of Interventions [11], the standard for conducting information
reviews in healthcare and pharmaceutical industries, it was conducted in the
spirit of the Cochrane systematic
review in that it was designed based on the principle that “science is
cumulative”, and by considering all available evidence, decisions could be made
that reflect the best science available. It also involves critical review and
critique of the published literature and at times weighting some manuscripts
over others in the same scientific field.
To
facilitate this review, combinations of key words (i.e., annoyance, noise,
environmental change, sleep disturbance, epilepsy, stress, health effect(s),
wind farm(s), infrasound, wind turbines(s), low frequency noise, wind turbine syndrome,
neighborhood change) were selected and entered into the Thomson Reuters
(formerly ISI) Web of KnowledgeSM. The Web of KnowledgeSM is a database that
covers over 10,000 high-impact journals in the sciences, social sciences, and
arts and humanities, as well as international proceedings coverage for over
120,000 conferences. The Web of KnowledgeSM comprises seven citation databases,
two of which are relevant to the search: the Science Citation Index Expanded
(SCI-Expanded) and the Social Sciences Citation Index (SSCI). The SCIExpanded includes
over 6,650 major journals across 150 scientific disciplines and includes all
cited references captured from indexed articles. Coverage of the literature spans
the year 1900 to the present. On average, 19,000 new records per
week are added to the SCI-Expanded. SSCI is a multidisciplinary index of the
social science literature. SSCI includes over 1,950 journals across 50 social
sciences disciplines from the year 1956 to the present. It averages 2,900 new
records per week. Use of this literature search platform means the most
up-to-date multidisciplinary studies published and peer-reviewed could be
obtained.
Although
hundreds of articles were found during the search, very few were related to the
association between potential health effects and wind turbines. For example, numerous
articles have been published about infrasound, but very few have been published
about infrasound and wind turbines. Indeed, only fifteen articles, published between
2003 and 2011, were found relevant [12-26]. What can be seen from these articles
is that the relationship between wind turbines and human responses to them is
extremely complex and influenced by numerous variables, the majority of which
are nonphysical. What is clear is that
some people living near wind turbines experience annoyance due to wind
turbines, and visual impact tends to be a stronger predictor of noise annoyance
than wind turbine noise itself. Swishing, whistling, resounding and pulsating/ throbbing
are sound characteristics most highly correlated with annoyance by wind turbine
noise for those people who noticed the noise outside their dwellings. Some people
are also disturbed in their sleep by wind turbines. In general, five key points
have come out of these peer-reviewed studies with regards to health and wind
turbines.
1.
People tend to notice sound from wind turbinesalmost linearly with increasing
sound pressure level
In the studies
designed to evaluate the Interrelationships amongst annoyance and wind
turbine noise, as well as the influence of subjective variables such as
attitude and noise sensitivity, Pedersen and Persson Waye [13-15] showed that
people tend to notice sound from wind turbines almost linearly with increasing
sound pressure level. Briefly, Pedersen and Persson Waye conducted
crosssectional studies (in 2004: n = 351; in 2007: n = 754) and gave people
questionnaires regarding housing and satisfaction with the living environment,
including questions about degree of annoyance experienced outdoors and indoors
and sensitivity to environmental factors, wind turbines (noise, shadows, and
disturbances), respondents’ level of perception and annoyance, and verbal
descriptors of sound and perceptual characteristics. The third section had
questions about chronic health (e.g., diabetes, tinnitus, cardiovascular
diseases), general wellbeing (e.g., headache, undue tiredness feeling tensed/stressed,
irritable) and normal sleep habits (e.g., quality of sleep, whether or not
sleep was disturbed by any noise source). The last section comprised questions
on employment and working hours. Of import, the purpose of the study was masked
in the questionnaires, which was done to reduce the potential for survey bias.
Of
the 754 respondents involved in the Pedersen and Persson Waye study [14], 307
(39%) noticed sound from wind turbines outside their dwelling (range of sound
pressure level: < 32.5, 32.5-35.0, 35.0-37.5, 37.5-40.0, and > 40.0
dB(A)) and the proportion of respondents who noticed sound increased almost
linearly with increasing noise. In the 37.5-40.0 dB(A) range, 76% of the 71
respondents reported that they noticed sound from the wind turbines; 90% of
respondents (n = 18) in the > 40.0 dB(A) category noticed sound from the
wind turbines. The odds of noticing sound increased by 30% for each increase in dB(A) category.
When data from both studies [13,14] were combined (n = 1095) results were the
same: the proportion of respondents
who noticed sound from wind turbines showed increased almost linearly with
increasing sound pressure level from roughly 5-15% of people noticing noise at
29 dB(A) to 45-90% noticing noise at 41 dB (A)[15].
In
2011 Pedersen [25] reported on the results of three cross-sectional studies conducted
in two areas of Sweden (a flat rural landscape (n = 351) and suburban sites
with hilly terrain (n = 754) and one location in the Netherlands (flat landscape
but with different degrees of road traffic intensity (n = 725)) designed assess
the relationship between wind turbine noise and possible adverse health effects.
Questionnaires were mailed to people in the three areas to obtain information about
annoyance and health effects in response to wind turbines noise. Pedersen included
questions about several potential environmental stressors and did not allow
participants to know that the focus of the study was on wind turbine noise,
again in an attempt to reduce self-reporting survey bias. For each respondent,
sound pressure levels (dB(A)) were calculated for nearby wind turbines. The
questionnaires were designed to obtain information about people’s response to noise
(i.e., annoyance), diseases or symptoms of impaired health (i.e., chronic
disease, diabetes, high blood pressure, cardiovascular disease, tinnitus,
impaired hearing), stress symptoms (i.e., headache, undue tiredness, feeling
tense or stressed,
feeling irritable), and disturbed sleep (i.e., interruption of the sleep by any
noise source). Results showed that the frequency of those annoyed with wind
turbines was related to an increase in sound pressure level as shown by odds
ratios (OR) with 95% confidence intervals (CI) greater than 1.0. Sleep interruption
was associated with sound level in two of the three studies (the areas with flat
terrain), but unlike the finding that people tend to notice sound from wind
turbines almost linearly with increasing sound pressure level, sleep
disturbance did not increase gradually with noise levels, but spiked at 40 dBA and
45 dBA.
2.
A proportion of people that notice sound from wind turbines find it annoying
Results of the
Pedersen and Persson Waye studies [13-15] also suggested that the proportion of
participants who were fairly annoyed or very annoyed remained quite level through
the 29-37 dB(A) range (no more than roughly 5%) but increased at noise levels
above 37 dB(A), with peaks at 38 db(A) and 41 dB(A), where up to 30% of people were
very annoyed. Respondents in the cross-sectional studies (and other studies
[12]) noted that swishing, whistling, resounding and pulsating/throbbing were
the sound characteristics that were most highly correlated with annoyance by
wind turbine noise among respondents who noticed the noise outside their
dwellings. This was also found by
Leventhall [16]. Seven percent of respondents (n = 25) from the Pedersen and
Persson Waye study [13] were annoyed by noise from wind turbines indoors, and this
was related to noise category; 23% (n = 80) were disturbed in their sleep by
noise. Of the 128 respondents living at sound exposure above 35.0 dB(A), 16% (n
= 20) stated that they were disturbed in their sleep by wind turbine noise. The
authors comment that some people may find wind turbine noise more annoying than
that of other types of noise (e.g., airplane and traffic) experienced at similar
decibel levels.
Similar
results were shown by Pedersen and Persson Waye [14]: a total of 31 of the 754
respondents said they were annoyed by wind turbine noise. In the < 32.5 to
the 37.5 dB(A) category 3% to 4% of people said they were annoyed by wind
turbine noise; in the 37.5-40.0 dB(A) category, 6% of the 71 respondents were
annoyed; and in the > 40.0 category, 15% of 20 of respondents said they were
annoyed by wind turbine noise. In addition, 36% of those 31 respondents who
were annoyed by wind turbine noise reported that their sleep was disturbed by a
noise source. Nine percent of those 733 respondents not annoyed said their
sleep was disturbed by a noise source. Results of Pedersen [25] showed similar
results: the frequency of those annoyed was related to an increase in sound
pressure level. Moreover, self reported health effects like feeling tense,
stressed, and irritable, were associated with noise annoyance and not to noise
itself (OR and 95% CI > 1.0). Sleep interruption, however, was associated
with sound level and annoyance (OR and 95%CI > 1.0). Pedersen notes that
this finding is not necessarily evidence of a causal relationship between wind
turbine noise and stress but may be explained by cognitive stress theory
whereby “an individual appraises an environmental stressor, such as noise, as
beneficial or not, and behaves accordingly”. In other words, it appears that it
is the change in the environment that is associated with the self-reported
health effects, not the presence of wind turbines themselves.
Keith
et al. [17] proposed that in a quiet rural setting, the predicted sound level
from wind turbines should not exceed 45 dB(A) at a sensitive receptor location
(e.g., residences, hospitals, schools), a value below the World Health
Organization guideline for sleep and speech disturbance,
moderate annoyance
and hearing impairment. The authors [17] suggest this level of noise could be
expected to result in a 6.5% increase in the percentage of highly annoyed
people. Since publication of the Keith et al. study, the WHO Europe Region has
released new Night Noise Guidelines for Europe [8] and state that: “The new
limit is an annual
average night exposure not exceeding 40 decibels (dB), corresponding to the
sound from a quiet street in a residential area”. The value of 40 dB is
considered the lowest observed adverse effect level (LOAEL) for night noise
based on the finding that an average night noise level over a year of 30-40 dB
can result in a number of effects on sleep such as body movements, awakening,
selfreported sleep disturbance and arousals [8]. The WHO states that even in
the worst cases these effects seem modest [8].
3. Annoyance is not only related to wind
turbine noise but also to subjective factors like attitude to visual impact,
attitude to wind turbines and sensitivity to noise
Pedersen and
Persson Waye [13] revealed that attitude to visual impact, attitude to wind
turbines in general, and sensitivity to noise were also related to the way
people perceived noise from turbines. For example, 13% of the variance in annoyance
from wind farms could be explained by noise and the odds that respondents would be annoyed by
noise from wind turbines increased 1.87 times from one sound category to the
next. When noise and attitude to visual impact was statistically assessed, 46%
of the variance in annoyance from wind farms could be explained and the odds
that respondents would be annoyed from wind turbines increased 5.05 times from one
sound category to the next. Statistical analyses showed that while attitude to
wind turbines in general and sensitivity to noise were also related to
annoyance, they did not have a greater influence on annoyance than visual
effect. Building on their 2004 paper, Pedersen and Persson Waye
[14] conducted a cross-sectional study in seven areas in Sweden across
dissimilar terrains and with different degrees of urbanization. Three areas were
classified as suburban; four as rural. Noise annoyance related to wind turbines
was also statistically related to whether or not people live in suburban or
rural areas and landscape (flat vs.
hilly/complex). Visual impact has come out as a stronger predictor of noise
annoyance than wind turbine noise itself. People who economically benefit from wind
turbines had significantly decreased levels of annoyance compared to individuals
that received no economic benefit, despite exposure to similar sound levels [18].
One
suggestion of the difference between rural and suburban areas is level of background
sound and interestingly, perception and annoyance was associated with type of landscape,
“indicating that the wind turbine noise interfered with personal expectations
in a less urbanised area... pointing towards a personal factor related to the
living environment” [14]. The authors also concluded that visual exposure
enhances the negative associations with turbines when coupled with audible
exposure. They also point out that this study
showed that aesthetics play a role in annoyance: “respondents who think of wind
turbines as ugly are more likely to appraise them as not belonging to the
landscape ind therefore feel annoyed” [14].
In
2007 Pedersen et al. [19] conducted a grounded theory study to gain a deeper
understanding of how people living near wind turbines perceive and are affected
by them. Findings indicated that the relationship between exposure and response
is complex and possibly influenced by variables not yet identified, some of
which are nonphysical. The notion that wind turbines are “intruders” is a
finding not reported elsewhere. A conclusion of this paper is
that when the impacts of wind turbines are assessed, values about the living
environment are important to consider as values are firmly rooted within a
personality and difficult to change.
In
2008, Pedersen and Larsman [20] conducted a study to assess visibility of wind
turbines, visual attitude and vertical visual angle (VVA) in different
landscapes. This study follows up on the findings of previous work showing a
relationship between noise annoyance in people living near wind turbines and
the impact of visual factors as well as an individual’s attitude toward noise
[13-15,25]. Overall, Pedersen and Larsman concluded that respondents in a landscape
where wind turbines could be perceived as contrasting with their surroundings
(i.e., flat areas) had a greater probability of noise annoyance than those in
hilly areas (where turbines were not as obvious), regardless of sound pressure
level, if they thought wind turbines were ugly, unnatural devices that would
have a negative impact on the scenery. The enhanced negative response could be linked
to aesthetical response, rather than to multi modal effects of simultaneous auditory
and visual stimulation. Moreover, VVA was associated with noise annoyance, especially
for respondent who could see at least one wind turbine from their dwelling, if
they were living in flat terrain and rural areas. Pedersen and Larsman suggest
that these results underscore the importance of visual attitude towards the
noise source when exploring response to environmental noise. In 2010 Pedersen
et al. [21] hypothesized that if high
levels of background sound can reduce annoyance by masking the noise from a
wind farm, then turbines could cause less noise annoyance when placed next to
motorways instead of quiet agricultural areas. In general, the hypothesis was
not supported by the available data [15], further providing support for the
notion of visual cue being a strong driver of annoyance.
4.
Turbines are designed not to pose a risk of photoinduced epilepsy
Harding et al.
[22] and Smedley et al. [23] investigated the relationship between
photo-induced seizures (i.e., photosensitive epilepsy) and wind turbine blade
flicker (also known as shadow flicker). This is an infrequent event, typically
modelled to occur less than 30 hours a year from wind turbine projects we have
reviewed and would be most common at dusk and dawn, when the sun is at the horizon.
Both studies suggested that flicker from turbines that interrupt or reflect sunlight
at frequencies greater than 3 Hz pose a potential risk of inducing
photosensitive seizures in 1.7 people per 100,000 of the photosensitive population.
For turbines with three blades, this translates to a maximum speed of rotation
of 60 rpm. The normal practice for large wind farms is for frequencies well
below this threshold.
Although
shadow flicker from wind turbines is unlikely lead to a risk of photo-induced
epilepsy there has been little if any study conducted on how it could heighten the
annoyance factor of those living in proximity to turbines. It may however be
included in the notion of visual cues. In Ontario it has been common practice
to attempt to ensure no more than 30 hours of shadow flicker per annum at any
one residence.
5.
The human ear responds to infrasound
Infrasound is
produced by physiological processes like respiration, heartbeat and coughing,
as well as man-made sources like air conditioning systems, vehicles, some industrial
processes and wind turbines. Salt and Hullar [24] provide data to suggest that
the assumption that infrasound presented at an amplitude below what is audible has
no influence on the ear is erroneous and summarize the results of previous
studies that show a physiological response of the human ear to low frequency noise
(LFN) and infrasound. At very low frequencies the outer hair cells
(OHC) of the cochlea may be stimulated by sounds in the inaudible range. Salt
and Hullar hypothesize that “if infrasound is affecting cells and structures at
levels that cannot be heard this leads to the possibility that wind turbine
noise could be influencing function or causing unfamiliar sensations”. These
authors do not test this hypothesis in their paper but suggest the need for
further research.
To
assess the possibility that the operation of wind turbines may create unacceptable
levels of low frequency noise and infrasound, O’Neal et al. [26] conducted a
study (commissioned by a wind energy developer, NextEra Energy Resources, LLC)
to measure wind turbine noise outside and within nearby residences of turbines.
At the Horse Hollow
Wind Farm in Taylor and Nolan Counties, Texas, broadband (A-weighted) and
one-third octave band data (3.15 hertz
to 20,000 hertz bands) were simultaneously collected from General Electric (GE)
1.5sle (1.5 MW) and Siemens SWT-2.3-93 (2.3 MW) wind turbines. Data were
collected outdoors and indoors over the
course of one
week under a variety of operational conditions (it should be noted that wind
speeds were low during the measurements; between 3.2 and 4.1 m/s) at two
distances from the nearest wind turbines: 305 meters and 457 meters. O’Neal et
al. found that the measured low frequency sound and infrasound
at both distances (from both turbine types at maximum noise conditions) were less
than the standards and criteria published by the cited agencies (e.g., UK DEFRA
(Department for Environment, Food, and Rural Affairs); ANSI (American National Standards
Institute); Japan Ministry of Environment). The authors concluded that results
of their study suggest that there should be no adverse public health effects
from infrasound or low frequency noise at distances greater than 305 meters
from the two wind turbine types measured.
Popular
Literature
Scientific
studies peer reviewed and published in scientific journals are one way of
disseminating information about wind turbines and health effects. The general
public does not always have access to scientific journals and often get their
information, and form opinions, from sources that are less accountable (e.g.,
the popular literature and internet). Some of the same key words used to obtain
references from the primary literature were entered into the common internet
search engine Google: “health effects
wind farms” returned 300,000 hits; “health effects wind turbines” returned
120,000 hits; “annoyance wind turbines” returned 185,000 hits and “sleep
disturbance wind turbines” returned 19,500 hits. What is apparent is that
numerous websites have been constructed by individuals or groups to support or
oppose the development of wind turbine projects, or media sites reporting on
the debate. Often these websites state the perceived impacts on, or benefits
to, human health to support the position of the individual or group hosting the
website. The majority of information posted on these websites cannot be traced
back to a scientific, peerreviewed source and is typically anecdotal in nature.
In some cases, the information contained on and propagated by internet websites
and the media is not supported, or is even refuted, by scientific research.
This serves to spread misconceptions about the potential impacts of wind energy
on human health, which either fuels or diminishes opposition to wind turbine
project development.
Works
by Dr. Michael Nissenbaum conducted at Mars Hill and Vinalhaven Maine [27] and
Dr. Nina Pierpont in New York [28] seem to be the primary popular literature studies
referenced on websites. These works suggest a causal link between human health
effects and wind turbines. Works by Dr. Robert McMurtry and Carmen Krogh, and
Lorrie Gillis, Carmen Krogh and Dr. Nicholas Kouwen [29] have also been used to
suggest a relationship between health and turbines. These works have been presented as
reports or as slide presentations on websites and authors of these studies have
presented their findings in various forua such as invited lectures, affidavits,
public meetings and open houses. Briefly, Nissenbaum evaluated 22 exposed
adults (defined as living within 3500 ft of an arrangement of 28 1.5 MW wind
turbines) and 27 unexposed adults (living about 3 miles away from the nearest turbine).
Participants were interviewed and asked a number of questions about their
perceived health, levels of stress and reliance on prescription medications in
relation to the turbines [27].
In
2009, a book entitled Wind Turbine Syndrome: A Report on a Natural Experiment
by Dr. Nina Pierpont, was self-published and describes “Wind Turbine Syndrome”,
the clinical name Dr. Pierpont coined for the collection of symptoms reported
to her by people residing near wind turbines [28]. The book describes a case
series study she conducted involving interviews of 10 families experiencing
adverse health effects and who reside near wind turbines. Similar to the process
followed by Nissenbaum, people living in proximity wind turbines were
interviewed about their health. For all of these works, selfreported symptoms generally
included sleep disturbance, headache, tinnitus (ringing in the ears), ear
pressure, dizziness, vertigo, nausea,
visual blurring, tachycardia (rapid heart rate), irritability, problems with
concentration and memory and panic episodes. These symptoms have been purported
to be associated with proximity to wind turbines, and specifically, to the
infrasound emitted by the turbines. It should be noted that of the 351 people assessed
by Pedersen and Persson Waye [13], 26% (91) reported chronic health issues
(e.g., diabetes, tinnitus, cardiovascular diseases), but these issues were not
statistically associated with noise levels. Results of Pedersen [25] showed
similar results: self reported health effects like feeling tense, stressed, and
irritable, were associated with noise annoyance and not to noise itself. Sleep
interruption, however, was associated with sound level and annoyance.
In
2007, Alves-Pereira and Castelo Brancohttp://www.windwatch.org/documents/industrial-wind-turbinesinfrasound-and-vibro-acoustic-disease-vad/
issued a press-release
suggesting that their research demonstrated that living in proximity to wind
turbines has led to the development of vibro-acoustic disease (VAD) in nearby home-dwellers.
It appears that this research has only been presented at a conference, has not
been published in a peer-reviewed journal nor has it undergone thorough scientific
review. Moreover, Alves-Pereira and Castelo Branco appear to be the primary
researchers that have promulgated VAD as a hypothesis for adverse health effects
and wind turbines. Indeed, Dr. Pierpont has noted that VAD is not the same
“wind turbine syndrome” [28].
To
date, these studies have not been subjected to rigorous scientific peer
review, and given the venue for their distribution and limited availability of
data, it is extremely difficult to assess whether or not the information
provided is reliable or valid. What is apparent, however, is that these studies
are not necessarily scientifically defensible: they do not contain noise
measurements, only measured distances from study participants to the closest
turbines; they do not have adequate statistical representation of potential
health effects; only limited rationale is provided for the selection of study
participants (in some cases people living in proximity to turbines have been excluded
from the study); they suffer from a small number of participants and appear to
lack of objectivity as authors are also known advocates who oppose wind turbine
developments. Unlike the questionnaires used by Pedersen et al. [13-15,25], the
purpose of the studies are not hidden from participants. In fact, the selection
process is highly biased towards finding a population who believes they have
been affected by turbines. This is not an attempt to discount the self-reported
health issues of residents living near wind turbines. Rather, it points out
that the self-reported
health issues
have not been definitively linked to wind turbines.
What
the peer reviewed literature and popular literature have in common is the conclusion
that wind turbines can be a source of annoyance for some people. Of note are
the different reasons and possible causes for annoyance. In the peer reviewed
studies, annoyance tends to peak in the > 35 dB(A) range but tends to be
more strongly related to subjective factors like visual impact, attitude to
wind turbines in general
(benign vs. intruders) and sensitivity to noise rather than noise itself from
turbines. In the popular literature, health outcomes tend to be more strongly related
to distance from turbines and the claim that infrasound is the causative factor.
Though sound pressure level in most of the peer reviewed studies was scaled to
dB(A) (but refer to O’Neal et al. [26] for actual measurements of low frequency
noise and infrasound), infrasound is a component of the sound measurements and
was inherently accounted for in
the studies.
Annoyance
Studies on the
health effects of wind turbines, both published and peer-reviewed and presented
in the popular literature, tend to conclude that wind turbines can cause annoyance
for some people. A number of governmental health agencies agree that while
noise from wind turbines is not loud enough to cause hearing impairment and are not causally
related to adverse effects, wind turbines can be a source of annoyance for some
people [1,30-34].
It
has been hypothesized that the self reported health effects (e.g., sleep
disturbance, headache, tinnitus (ringing in the ears), ear pressure, dizziness,
vertigo, nausea, visual blurring, tachycardia (rapid heart rate), irritability,
problems with concentration and memory, and panic episodes) are related to
infrasound emitted from wind turbines [28]. Studies where biological effects
were observed due to infrasound exposure were conducted at sound pressure
levels (e.g., 145 dB and 165 dB [5,16]; 130 dB [7]) much
greater than what is produced by wind turbines (e.g., see O’Neal et al. [26]).
Infrasound is not unique to wind turbines but is ubiquitous in the environment due to natural
and man-made sources, meaning that people living near wind turbines were exposed
to infrasound prior to turbine operation. For example, Berglund and Hassmen [35]
reported that infrasound (a component of low frequency sound) is emitted from
road vehicles, aircraft, industrial machinery, artillery and mining explosions,
air movement machinery including wind turbines, compressors, and
air-conditioning units, and Leventhall [5] reported that infrasound comes from natural
sources like meteors, volcanic eruptions and ocean waves. Indeed,
many mammals communicate using infrasound [36]. Given the low sound pressure levels
of infrasound emitted from wind turbines and the ubiquitous nature of these
sounds, the hypothesis that infrasound is a causative agent in health effects
does not appear to be supported.
Peer
reviewed and scientifically defensible studies suggest that annoyance and health
effects are more strongly related to subjective factors like visual impact and
attitude to wind turbines rather than to noise itself (both audible and
inaudible [i.e., infrasound]). Indeed, many of the self reported health effects
are associated with numerous issues, many of which can be attributed to anxiety
and annoyance (e.g., Pedersen 2011 [25]). Shargorodsky et al. [37] published
that roughly 50 million adults in the United States reported having tinnitus,
which is statistically correlated (based on 14,178 participants) to age,
racial/ethnic group, hypertension, history of smoking, loud leisure-time, firearm,
and occupational noise, hearing impairment and generalized anxiety disorder
(based on 2265 participants) identified using a World Health Organization
Composite Diagnostic Interview). In fact, the odds of tinnitus being related to anxiety
disorder were greatest for any of the variables tested. Folmer and Griest [38],
based on a study of 174 patients undergoing treatment for tinnitus at the Oregon
Health Sciences University Tinnitus Clinic between 1994 and 1997, reported that
insomnia is associated with greater severity of tinnitus. Insomnia is also associated
with anxiety and annoyance. Bowling et al. [39] described statistically that
people’s perceptions of neighbourhood environment can influence health.
Perceptions of problems in the area (e.g., noise, crime, air quality, rubbish/ litter,
traffic, graffiti) were predictive of poorer health score. In their 2003 publication
Henningsen and Priebe [40] discussed the characteristics of “New Environmental Illness”,
illnesses where patients strongly believe their symptoms are caused by
environmental factors, even though symptoms are not consistent with empirical
evidence and medically unexplained. A key component to such illnesses is the
patient’s attitude toward the source of the environmental factor. What is more,
health effects from annoyance have been shown to be mitigated though behavioural
and cognitive behavioural interventions [30,41], lending support to Pedersen’s
[25] conclusion that health effects can be explained by cognitive stress
theory. In other words, it appears that it is the change in the environment
that is associated with health effects, not a turbine-specific variable like
infrasound.
Conclusions
Wind power has
been harnessed as a source of power around the world. Debate is ongoing with
respect to the relationship between reported health effects and wind turbines,
specifically in terms of audible and inaudible noise. As a result, minimum
setback distances have been established world-wide to reduce or avoid potential
effects for people living in proximity to wind turbines. People interested in
this debate turn to two sources of information to make informed decisions:
scientific peerreviewed studies published in scientific journals and the popular
literature and internet.
We
found that conclusions of the peer reviewed literature differ in some ways from
the conclusions of the studies published in the popular literature. What both
types of studies have in common is the conclusion that wind turbines can be a
source of annoyance for some people. In the peer reviewed studies, wind turbine
annoyance and some reported health effects (e.g., sleep disturbance) have been
statistically associated with wind turbine noise especially when found at sound
pressure levels greater than 40 db(A), but found to be more strongly related to
subjective factors like visual impact, attitude to wind turbines in general and
sensitivity to noise. To date, no peer reviewed scientific journal articles
demonstrate a causal link between people living in proximity to modern wind turbines,
the noise (audible, low frequency noise, or infrasound) they emit and resulting
physiological health effects. In the popular literature, self-reported health
outcomes and annoyance are related to distance from turbines and the claim is
made that infrasound is the causative factor for the reported effects, even
though sound pressure levels are not measured. Infrasound is not unique to wind
turbines and the self reported health effects of people living in proximity to
wind turbines are not unique to wind turbines. Given that annoyance appears to
be more strongly related to visual cues and attitude than to noise itself, self
reported health effects of people living near wind turbines are more likely
attributed to physical manifestation from an annoyed state than from
infrasound. This hypothesis is supported by the peer-reviewed literature
pertaining to environmental stressors and health.
The
authors have spent countless hours at community public consultation events hosted
by proponents announcing new projects and during updates to their environmental
assessment process. Historically, citizens’ concerns about wind turbine
projects appeared to involve potential impact on property values and issues
surrounding avian and bat mortality. Increasingly in North America the issue
surrounding fears of potential harm to residents’ health have come to the
forefront of these meetings. It is clear that the announcement of a new project
can led to a heightened sense of anxiety and annoyance in some members of the
public, even prior to
construction and
operation of a wind turbine project. The authors have been involved in all
manner of risk communication, consultation and risk assessment projects in the
energy sector in Canada and it has been our experience that this heightened
sense of annoyance, agitation or fear is not unique to the wind turbine sector.
Whether the proposed project is a wind turbine, gas-fired
station, coal
plant, nuclear power plant, or energy-fromwaste incinerator we have seen a level
of concern in a sub-set of the population that goes well beyond anything that
would be considered the traditional sense of not-inmy- back-yard (NIMBY). These
people genuinely are fearful about the potential health effects that the
project may cause, regardless of the outcomes of quantitative assessments that
demonstrate that there is a de minimus of potential risk in living next to a
particular facility. The literature and our own experience highlight the need
for informative discussions between wind power developers and community members
in order to attempt to reduce the level of apprehension. We encourage continued
dialogue between concerned citizens and developers once projects become
operational.
Canadian
public health agencies subscribe to the World Health Organization definition of
health. “Health is a state of complete physical, mental and social well being
and not merely the absence of infirmity or disease”, a quote often used by both
sides of the wind turbine debate. We believe that the primary role of the
environmental health/ risk assessment practitioner is to ensure that
physiological manifestation of infirmity or disease is not predicted to occur
from exposure to an environmental contaminant. In terms of wind power, ethics
dictate an honest reporting of the issues surrounding annoyance and the fact
that it appears that a limited number of people have self-reported health
effects that may be attributed to the indirect effects of visual and
attitudinal cue. We believe that any physiological based effect can be
mitigated through the use of appropriate setback distances. However, it is not
clear that for this hypersensitive annoyed population that any set back
distance could mitigate the indirect effects. Therefore, it is up to our
elected officials and ministerial staff when establishing an energy source
hierarchy to weigh all of the information before them to determine the
trade-offs between “mental and social well-being” of these individuals against
the larger demand for energy and its source.
A
number of governmental health agencies agree that while noise from wind
turbines is not loud enough to cause hearing impairment and are not causally
related to adverse effects, wind turbines can be a source of annoyance for some
people. Ultimately it is up to governments to decide the level of acceptable
annoyance in a population that justifies the use of wind power as an alternative
energy source.
Assessing
the effects of wind turbines on human health is an emerging field, as
demonstrated by the limited number of peer-reviewed articles published since
2003. Conducting further research into the effects of wind turbines (and
environmental change) on human health, emotional and physical, as well as the
effect of public consultation with community groups in reducing preconstruction
anxiety, is warranted. Such an undertaking should be
initiated prior to public announcement of a project, and could involve baseline
community health and attitude surveys, baseline noise and infrasound
monitoring, observation and questionnaires administered to public during the
siting and assessment process, noise modeling and then post-construction follow-up
on all of the aforementioned aspects. Regardless it would be imperative to
ensure robust study design and a clear statement of purpose prior to study
initiation.
We
believe that research of this nature should be undertaken by multi-disciplinary
teams involving, for example, acoustical engineers, health scientists,
epidemiologists, social scientists and public health physicians. Ideally
developers, government agencies, consulting professionals and non-government
organizations would form collaborations
in attempt to
address these issues.
List
of Abbreviations
ANSI: American
National Standards Institute; CI: Confidence intervals; dB(A):
A-weighted
decibels; DEFRA: Department for Environment, Food, and Rural
Affairs; LFN:
low frequency noise; LOAEL: lowest observed adverse effect
level; MW: mega
watt; O.Reg.: Ontario Regulation; OR: odds ratio; OHC: outer
hair cells; REA:
Renewable Energy Approval; SCI: Science Citation Index; SSCI:
Social Sciences
Citation Index; VAD: vibro-acoustic disease; VVA: vertical
visual angle;
WHO: World Health Organization
Acknowledgements
None
Author
details
1Intrinsik
Environmental Sciences Inc., 1790 Courtwood Crescent, Ottawa ON,
K2C 2B5, Canada.
2Intrinsik Environmental Sciences Inc., 6605 Hurontario
Street, Suite
500, Mississauga, ON, L5T 0A3, Canada.
Authors’
contributions
LDK and CAO both
researched and wrote the manuscript. Both authors read
and approved the
final version.
Competing
interests
In terms of
competing interests (financial and non-financial), the authors
work for a
consulting firm and have worked with wind power companies.
The authors are
actively working in the field of wind turbines and human
health. Dr.
Ollson has acted as an expert witness for wind power companies
during a number
of legal hearings. Although we make this disclosure, we
wish to
reiterate that as independent scientific professionals our views and
research are not
influenced by these contractual obligations. The authors are
environmental
health scientists, trained and schooled, in the evaluation of
potential risks
and health effects of people and the ecosystem through their
exposure to
environmental issues such as wind turbines.
Received:
2 May 2011 Accepted: 14 September 2011
Published:
14 September 2011
References
1.
World Health Organization (WHO): Fourth Ministerial Conference on
Environment
and Health. Energy, Sustainable Development and Health;
2004.
2.
Devine-Wright P: Beyond NIMBYism: towards an integrated framework
for
understanding public perceptions of wind energy. Wind Energy 2005,
8:125-139.
3.
Ontario Power Authority (OPA), 2008 Annual Report: On the Path to a
Sustainable
Electricity Future. 2008.
4. Bronzaft
AL: The effect of a noise abatement program on reading ability.
J
Environ Psychol 1981, 1:215-222.
5.
Leventhall G, Pelmear P, Benton S: A Review of Published Research on
Low
Frequency Noise and its Effects. Department for Environment, Food
and
Rural Affairs, London, UK; 2003.
6.
Kristiansen J, Mathiesen L, Nielsen PK, Hansen AM, Shibuya H, Petersen HM,
Lund
SP, Jørgensen MB, Søgaard K: Stress reactions to cognitively
demanding
tasks and open-plan office noise. Int Arch Occup Environ
Health
2009, 82:631-641.
7.
Yuan H, Long H, Liu J, Qu L, Chen J, Mou X: Effects of infrasound on
hippocampus-dependent
learning and memory in rats and some
underlying
mechanisms. Environ Toxicol Pharm 2009, 28:243-247.
8.
World Health Organization Europe: Night Noise Guidelines for Europe.
2009,
ISBN 978 92 890 4173 7.
9.
Ontario Ministry of the Environment: Development of Noise Setbacks for
Wind
Farms Requirements for Compliance with MOE Noise Limits 2009.
10.
Walsh O: No Global Standards 2010 [http://www.windvigilance.com/
international-symposium].
11.
Higgins JPT, Green S, editors: Cochrane Handbook for Systematic Reviews
of
Interventions, Version 5.0.2. The Cochrane Collaboration 2009.
12.
van den Berg GP: Effects of the wind profile at night on wind turbine
sound.
J Sound Vibrat 2003, 277:955-970.
13.
Pedersen E, Persson Waye K: Perception and annoyance due to wind
turbine
noise - a dose - response relationship. J Acoust Soc Am 2004,
116:3460-3470.
14.
Pedersen E, Persson Waye K: Wind turbine noise, annoyance and selfreported
health
and well-being in different living environments. J Occup
Environ
Med 2007, 64:480-486.
15.
Pedersen E, Persson Waye K: Wind turbines - low level noise sources
interfering
with restoration? Environ Res Lett 2008, 3:1-5.
16.
Leventhall G: Infrasound from wind turbines - fact, fiction or deception?
Can
Acoust 2006, 34:29-36.
17.
Keith SE, Michaud DS, Bly SHP: A proposal for evaluating the potential
health
effects of wind turbine noise for projects under the Canadian
Environmental
Assessment Act. J Low Freq Noise V A 2008, 27:253-265.
18.
Pedersen E, van den Berg F, Bakker R, Bouma J: Response to noise from
modern
wind farms in The Netherlands. J Acoust Soc Am 2009,
126:634-643.
19.
Pedersen E, Hallberg LR-M, Persson Waye K: Living in the vicinity of wind
turbines–a
grounded theory study. Qualitative Research in Psychology 2007,
4:49-63.
20.
Pedersen E, Larsman P: The impact of visual factors on noise annoyance
among
people living in the vicinity of wind turbines. J Environ Psychol
2008,
28:379-89.
21.
Pedersen E, van den Berg F, Bakker R, Bouma J: Can road traffic mask the
sound
from wind turbines? Response to wind turbine sound at different
levels
of road traffic. Energy Policy 2010, 38:2520-2527.
22.
Harding P, Wilkins A: Wind turbines, flicker, and photosensitive epilepsy:
Characterizing
the flashing that may precipitate seizures and optimizing
guidelines
to prevent them. Epilepsia 2008, 49:1095-98.
23.
Smedley ARD, Webb AR, Wilkins AJ: Potential of wind turbines to elicit
seizures
under various meteorological conditions. Epilepsia 2010,
51:1146-1151.
24.
Salt AN, Hullar TE: Responses of the ear to low frequency sounds,
infrasound
and wind turbines. Hear Res 2010, 268:12-21.
25.
Pedersen E: Health aspects associated with wind turbine noise–Results
from
three field studies. Noise Control Eng J 2011, 59:47-53.
26.
O’Neal RD, Hellweg Jr, Lampeter RM: Low frequency noise and infrasound
from
wind turbines. Noise Control Eng J 2011, 59:135-157.
27.
Nissenbaum M: Affidavit of Dr. Michael M. Nissenbaum. [http://www.
wind-watch.org/documents/affidavit-of-dr-michael-m-nissenbaum-m-d/].
28.
Pierpont N: Wind Turbine Syndrome Santa Fe, NM: K-Selected Books; 2009.
29.
Krogh K, Gillis L, Kouwen N: A self-reporting survey: adverse health
effects
with industrial wind turbines and the need for vigilance. Wind
Vigilance
for Ontario Communities [http://5468964569013158095-a-
1802744773732722657-s-sites.googlegroups.com/site/windvigilancecom/
healt_survey_rev14final.pdf?attachauth=ANoY7cpIDenR6Eib4UJc
4SF7PTCtAT_SA73tC9MnPHDzR22r3AYn7hZIh0c
PyETeKl4lbkal2GMyyhydn6NuzAp5e9BGnDWc
aJlKqC6Ui_tkKvVS_U_eUdydnYt-EpqvskDtJgVF_c
DNsbND596DS4C2_Ofk8VwXYrP_aAHk8zkwfCuQWrec
zfRDbiBRDShMnoPq2PifKvmHS7LNfOkGkouIWNdu3xAkeA%3D%
3D&attredirects=0].
30.
Leventhall G, Benton S, Robertson D: Coping strategies for low frequency
noise.
J Low Freq Noise V A 2008, 27:35-52.
31.
Chatham-Kent Public Health Unit: The Health Impact of Wind Turbines: A
Review
of the Current White, Grey and Published Literature 2008.
32.
Minnesota Department of Health Environmental Health Division: Public
Health
Impacts of Wind Turbines 2009.
33.
Chief Medical Officer of Health (CMOH) Ontario: The Potential Health Impact
of
Wind Turbines 2010.
34.
Australian Government, National Health and Medical Research Council:
Wind
Turbines and Health: A Rapid Review of the Evidence 2010.
35.
Berglund B, Hassmen P: Sources and effects of low-frequency noise. J
Acoust
Soc Am 1996, 99:2985-3002.
36.
Langbauer WR: Elephant Communication. Zoo Biol 2000, 19:425-445.
37.
Shargorodsky J, Curhan GC, Farwell WR: Prevalence and Characteristics of
Tinnitus
among US Adults. Am J Med 2010, 123:711-718.
38.
Folmer RL, Griest SE: Tinnitus and Insomnia. Am J Otolaryngol 2000,
21:287-293.
39.
Bowling A, Barber J, Morris R, Ebrahim S: Do perceptions of
neighbourhood
environment influence health? Baseline findings from a
British
survey of aging. J Epidemiol Community Health 2006, 60:476-483.
40.
Henningsen P, Priebe S: New environmental illnesses: What are their
characteristics?
Psychother Psychosom 2003, 72:231-234.
41.
Tazaki M, Landlaw K: Behavioural mechanisms and cognitive-behavioural
interventions
of somatoform disorders. Int Rev Psychiatr 2006, 18:67-73.
doi:10.1186/1476-069X-10-78
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