Here is one of the papers (proofs of evidence). by:
Professor Walter Holland CBE MD FRCP FFPHM
#PROOF OF EVIDENCE
#NOISE AND HEATH
#PERSONAL DETAILS
#SUMMARY
#INTRODUCTION
#EFFECTS OF NOISE
#NOISE-INDUCED
HEARING LOSS
#INTERFERENCE
WITH COMMUNICATION
#Prediction of
speech interference
#Scholastic Performance
#EFFECTS OF NOISE ON
SLEEP
#Assessing sleep
disturbance
#Criteria for
sleep interference
#Effects of Sleep
Disturbance
#USE OF
SEDATIVES AND OTHER PHARMACOLOGICAL AGENTS
#EXTRA-AUDITORY
HEALTH EFFECT
#Effects on blood
pressure
#Effects on blood
chemistry
#Effects on Heart
Disease
#Total Mortality
#Immunological Effects
#Pregnancy, Foetal
development
#Mental Health
#CONCLUSION
#APPENDIX
#CRITIQUE OF
OLLERHEAD ET AL
#REFERENCES
HACAN
Heathrow Association for the Control of Aircraft Noise
President: Professor Walter Holland CBE MD FRCP FFPHM
PO Box 339, Richmond, Surrey TW9 3RB
Tel: 0181 876 0455
Fax: 0181 878 0881
W. W. HOLLAND
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June 1997
I am 68 years old and qualified in Medicine in 1954 from St.
Thomas' Hospital Medical School. I have an
Honours BSc degree in Physiology and obtained Honours in the MB,
BS examinations. I obtained an MD
and have Fellowships of the Royal College of Physicians of both
London and Edinburgh, the Royal College
of General Practitioners, the Royal College of Pathologists and
the Faculty of Public Health Medicine. I was
elected to the Johns Hopkins Society of Scholars in 1970, and I
have Honorary Degrees from the
Universities of Bordeaux and Berlin. I was the first Sawyer
Scholar in Residence at Case Western Reserve
Medical School, Cleveland. I have been a Fogarty Scholar-in-Residence
at the National Institutes of Health,
in Bethesda in the United States. I have been a visiting
Professor at Harvard University Medical School;
Monash Medical School, Melbourne; Stanford University, Palo Alto;
University of California, Los Angeles;
University of Saarbrucken, Bordeaux; and Free University of
Berlin. I was awarded the prize of "Europe et
Médicine" in 1994, and was elected "Hero of Public
Health" by Johns Hopkins University School of
Hygiene. Amongst the many lectures I have given the most
prestigious are the Harben Lecture, Royal
Institute of Public Health; the Cruickshank Lecture,
International Epidemiology Association; and the Queen
Elizabeth, Queen Mother Lecture of the Faculty of Public Health
Medicine in 1995. I am the Rock Carling
Lecturer 1997 (The development of Public Health) of the Nuffield
Provincial Hospitals Trust.
At the present moment, I am Emeritus Professor of Public
Health Medicine and Professorial Fellow at LSE
Health in the London School of Economics. I am President of the
Heathrow Association for the Control of
Aircraft Noise (HACAN). For some thirty years, I directed the
Department of Public Health Medicine and
Health Services Research Unit at St. Thomas' Hospital Medical
School, now the United Medical and Dental
School. I was President of the Faculty of Public Health Medicine
and of the International Epidemiological
Association. I have participated in a wide variety of Research on
Health and Health Services, both in this
country and abroad, published about 300 original papers and books
and have been Editor in Chief of the
Oxford Textbook of Public Health, which is now in its third
edition.
I have acted as an adviser and member of a large number of
governmental bodies, WHO, the European
Union and other international and national bodies. In particular,
I am a member of the WHO Expert
Advisory Panel on health situation trends and assessment and I
was the Chairman of the WHO Global
Scientific and Advisory Group Integrated Programme for Community
Health in Non-Communicable
Diseases. In addition I am a member of the Executive Committee of
the Stroke Association and Chairman of
its Research Committee. I have acted as an advisor to the U.S.
Environmental Protection Administration
(EPA) and its predecessor, the Japanese Ministry of Health on
Environmental issues, and have served on
numerous Department of Health, MRC and other UK committees
concerned with the environment and
health.
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1.1. The need to minimize noise pollution in all its forms in
order to improve local environmental quality and
reduce health risks is now recognized by all, including the
Department of Health and the Department of the
Environment. It is ludicrous that the Department of Transport
does not apply the same criteria to aircraft
noise.
1.2. The effects of noise cause interference with
communication, which leads to interference with speech and
scholastic performance, at the levels common near airports.
1.3. Noise is the most common source of sleep disturbance and
sleep disruption. These effects are related to
the level of noise and are dose-dependent. Demonstrable changes
are seen from 45 dB(A) in almost all
studies.
1.4. Sleep disturbance leads to deficits in performance, particularly vigilance and cognition.
1.5. Individuals living near airports increase their use of sedatives and anti-asthmatic drugs.
1.6. Noise has been shown to be associated with significant
elevations of blood pressure, increased levels of
catecholamines, epinephrine and nor-epinephrine as well glucose,
white cells, plasma viscosity, total
triglycerides and total cholesterol. Thus the risk factors for
heart disease are increased.
1.7. Total mortality was increased in one area near Los Angeles airport.
1.8. Noise affects the immune system.
1.9. Noise has been shown to lower birth weight, increase the
frequency of prematurity, and damage
children's hearing while in utero.
1.10. There is a close relationship between noise sensitivity
and the liability to develop psychiatric symptoms.
It is estimated that about one third of the population is noise-sensitive.
1.11. The most frequently quoted study in the UK on aircraft
noise is by Ollerhead et al. This is
fundamentally flawed and inconsistent with the findings of
studies in other countries. Other countries have
shown how aberrant the findings are. The major reasons for
dismissing the findings are:
a) The methods of site selection - too few, too heterogeneous etc.
b) The methods of subject selection - highly selected, not adequately
described etc.
c) The lack of checks between the measurement of noise and the exposure to noise of the subjects.
d) The measurements of sleep disturbance by wrist movements
which do not correlate with the usually
accepted measure of brain activity.
e) The lack of a dose-response relation - since measurements were only made at high levels of noise.
f) The lack of critical discussion - e.g. there was less disturbance if the windows were open!
g) The conclusion that only 5% of the population were woken by
aircraft - and yet 23% complained of this!
A very strange, not addressed, discrepancy.
h) The fundamental disregard of the principle that the
investigators should be impartial, provide unemotional
conclusions and that the findings tabulated correlate with the
text.
1.12. Noise influences health and well-being. The higher the
level of noise the greater the damage. Most
authorities conclude that an "acceptable" level of
noise is 35 dB(A) - 45 dB(A). This is well below the levels
to which many of our members are exposed.
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2.1 In 1984 the Eyre Report on the expansion of Heathrow (Chapter
42, para 9.25) stated "Although I was referred to
documentation on the subject (health) I heard little expert
evidence on this matter. It is a potentially important topic but
the
material before me was so inconclusive that I do not believe I
can usefully comment".
2.2 It is difficult, in retrospect, to speculate on the
reasons for this comment but I hope that this paper, which
summarizes the published results of recent work, will demonstrate
both the scientific basis of the concern we
have with the effects of noise, as well as the conclusions of
supra-governmental (WHO) and governmental
bodies.
2.3 In the UK the most recent expression of concern is the
National Environmental Health Action Plan,
issued by the Department of the Environment (1). This recognizes
the vital influence on health of the
environment and is intended as a guide to the next steps in
improving environmental health in the UK. It has
been signed by the Secretaries of State for the Environment,
Northern Ireland, Health, Scotland and Wales.
For noise, chapter 3.7, page 72, states that the objective is
"to reduce exposure to noise pollution that
presents a significant threat to health, well-being and quality
of life".
2.4 The Government's aim "is to minimize noise pollution
in all its forms, in order to improve local
environmental quality and reduce the health risks posed by
excessive noise" (p. 72). The document records
the change in noise complaints received by Environmental Health
Officers over the period 1983/4 to 1992/3.
Complaints about aircraft noise rose more over this period than
any other source, from an index of 100 to
over 400; the next commonest cause was for domestic premises, 100
to about 280. It should be noted that,
in general, complaints about noise increased 2.5 times over this
period, but for aircraft noise more than
four-fold (17 million to 73 million).
2.5 The document lists a variety of ways whereby noise can be
tackled at source and prevented from
becoming a problem. Of particular relevance to the T5 Inquiry is
the emphasis given to land use planning,
p.73, and advice given in "Planning Policy Guidance Note 24.
Planning and Noise", (2) which advises "local
planning authorities on the issues to be considered in
determining planning applications for noise sensitive and
noise generating developments" (p. 73).
2.6 A Private Member's Bill, the Noise Bill, which it is hoped
will receive Royal Assent in the summer,
proposes that night-time neighbour noise on which complaints of
sleep disturbance are likely to occur must
exceed 35 dBLAeq, T and exceed the underlying noise level by at
least 10 dB. It is stated that the
government will bring into force the power to confiscate noise
making equipment in the Autumn 1996, and
will introduce a new night noise offence from April 1997.
2.7 It is astonishing that it is only now that legislative
action is being taken, 30 years after the Chief Medical
Officer stated in his Annual Report on Health in England and
Wales (1966) (pp. 126-127) that "noise today
has become a problem because it increasingly interferes with
normal existence". He also commented that "air
traffic noise --- is a serious problem in areas close to some
airports". He reported that households and
schools were to be fitted with double glazing. He stated that
apart from interfering with communication and
concentration it becomes a health problem in its broader sense
when sleep is interfered with. He considered
that noise disturbs mental and social health as well as causing
physical damage. The level he suggested above
which damage occurs is that recommended by the Wilson Committee (Minister
for Science, 1963), the
so-called Speech Interference Level of 55dBA. He deplored the
haphazard legal mechanisms in England to
control noise and contrasted these with the stricter controls in
Austria and Germany.
2.8 Although I recognize that since the 1920's aircraft noise
has been exempt from these neighbourhood
controls I will show that this is no longer warranted and that
sufficient evidence exists that BAA should be
subject to similar constraints as other bodies, governmental and
non-governmental, which damage the
environment and health, as indicated in the Department of
Environment document.
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3.1 Noise-induced hearing loss is probably the most well-defined
of the effects of noise. Predictions of
hearing loss from various levels of continuous and varying noise
have been extensively researched and are no
longer controversial. The levels of noise from aircraft in and
around Heathrow are very unlikely to cause
hearing loss, except to those employed at Heathrow. This is not a
matter on which I intend to comment.
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B. INTERFERENCE WITH COMMUNICATION.
3.2 Noise can mask important sounds and disrupt communication
between individuals in a variety of settings.
This process can cause anything from slight irritation to a
serious safety hazard, because of the failure to hear
the warning sounds of imminent danger. Of great concern is the
disruption of effective communication
between teachers and pupils in schools.
1. Prediction of speech interference.
3.3 A variety of studies have been done to develop adequate
methods to describe this and to suggest
appropriate levels for prophylaxis (e.g. 3,4)
3.4 Noise can disrupt communication in the classroom, which
has led to the nickname "jet-pause" teaching.
Cohen and Weinstein (6) reviewed several studies in 1981, which,
after controlling for socio-economic
factors, indicated that the academic performance of children in
quiet schools is better than in noisy schools.
They also showed that reading achievement is affected,
particularly when the children also live in noisy areas.
3.5 More recently these effects have been explored thoroughly
in Germany and Sweden. Thus Hygge (7)
showed that the impairment of reading in 12-14 year olds was
about 23%, if exposed to aircraft or train
noise. Schmeck and Ponstka (8) showed a greater propensity to
develop anxiety disorders, particularly in
girls, if children were exposed to the noise of low-flying
aircraft.
3.6 Of even greater note is the work of Bullinger and her
colleagues (9). They took the opportunity to study
9-12 year old children in both an urban and a rural area before
the new Munich airport was opened. They
studied children around the old and new airport before and after
the switch to the new airport was made.
Results available so far show that there is impairment of reading
ability in children exposed to aircraft noise,
and that improvement only occurs very gradually after the noise
is reduced. Physiological changes are not as
clear-cut - children exposed to airport noise have diminished
blood pressure reactivity and increased levels
of cortisol, compared to those not exposed.
3.7 That noise can interfere with the educational process and
produce scholastic decrements has been
accepted in the United States (10).
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3.8 Noise is one of the most common forms of sleep disturbance.
Aircraft noise can also cause sleep
disruption
1. Assessing sleep disturbance.
3.9 Noise can cause the sleeper to awaken repeatedly and to
report poor sleep quality the next day, but it
can also produce effects of which the sleeper is unaware. These
latter include - changes from heavier to
lighter sleep, reductions in rapid eye movement (REM) sleep,
increases in body movement, changes in
cardiovascular responses, and mood changes and performance
decrements the next day. The ways these
disturbances are measured are by Electroencephelography (EEG,
brain activity potentials),
electrocardiography (ECG, activity of the heart),
electromyography (EMG, activity of the muscles),
electro-oculography (EOG, activity of the eyes), clinical
observation, self assessment and accelerometry to
measure the motion of the bed frame.
3.10 There is an enormous literature on sleep research and I
only intend to summarize and highlight relevant
findings. All work agrees that intermittent and impulsive noise
is more disturbing than continuous noise of
equivalent energy. Older people are more likely to have their
sleep disturbed than younger people. Sleep
disturbance from noise is greater in the early hours of the
morning, when individuals spend more time in
lighter sleep stages.
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2. Criteria for sleep interference
3.11 A large number of publications have addressed the
relationship between level of noise and sleep
disturbance. These have been reviewed in detail by a variety of
bodies, e.g. WHO (11), the Health Council
of the Netherlands (12), US Environmental Protection Agency (13).
The WHO document (11) states that
"measurable (sleep disturbance) effects start from about 30dBALAeq"
-- (p.151). They continue "it is
especially important to limit the noise events exceeding 45dBA
where the background level is low" (p. 151).
The US EPA "identified an indoor DNL of 45dB, which
translates to a night time average sound level of
35dB, as necessary to protect against sleep disturbance".
3.12 The Dutch report (12) does not lay down any specific
levels but illustrates in two figures the percentage
of awakenings and the percentage of sleep stage changes at
different sound exposure levels in dB(A) in 5
studies performed in the past 20 years. At 45dBA there is, in
most studies, about 10% awakenings and 20%
of sleep stage changes. The aberrant finding that they illustrate
is the Ollerhead (14) study, which shows a
much lower level of awakenings. This is not surprising in view of
the gross inadequacies of this study. A
detailed critique is appended to this report.
3.13 The WHO, EPA and Dutch Council Report stress the need to
protect the public from sleep
disturbance and they raise the question of whether, at night,
lower levels would be more appropriate. Only
the UK study, quite remarkably, does not start to measure effects
until the sound level is 60dB or more. But
as the appendix shows, this study has so many problems that it is
remarkable that the Department of
Transport continues to quote from it.
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3. Effects of Sleep Disturbance.
3.14 The effects of disturbed sleep are well known in the
Armed Services and amongst pilots. They have
been comprehensively summarized in the report by AGARD (15). The
report emphasizes the importance of
adequate, uninterrupted sleep in order that air crew be able to
perform adequately - "Sleep is essential to
sustain high levels of vigilance and maintain effectiveness. The
adverse effects of sleep loss extending beyond
24 hours are well recognized, but impairment related to less
severe degrees of sleep loss or to irregularity of
sleep, both of which are particularly relevant to air operations,
is equally important" (p.63). The other armed
services have similar concerns.
3.15 The problem in the work-place has been recognized, in
particular, with shift workers. All studies show
that lack of sleep reduces productivity, there is a decline in
cognitive ability and decision-making becomes
poorer. One of the most recent publications (16) analyses, and
summarizes the data from 19 original studies.
They conclude that sleep-deprived subjects performed at a
significantly lower level than non-sleep-deprived
subjects; thus it is suggested that the average performance of a
sleep-deprived subject is only at about 9% of
the non-deprived group! They found that cognitive performance was
more affected than motor performance,
and mood was much more affected than either cognitive or motor
performance. Of even more concern, in
relation to aircraft noise, partial sleep deprivation (i.e.
multiple awakenings e.g. due to morning flight arrivals)
had "a much stronger overall effect on the dependent
measures than either short-term or long-term sleep
deprivation". (p.324) This analysis of many studies confirms
the finding by Bonnet (17) of the importance of
moderate sleep disruption..
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D. USE OF SEDATIVES AND OTHER PHARMACOLOGICAL AGENTS.
3.16 A recent pilot study has investigated whether the use of
pharmacy data can identify effects of noise
exposure in the Netherlands (18). The use of various drugs was
studied in and around Schipol airport and
compared to other, non-exposed areas.
3.17 It is shown that in noisy areas sedative use was 8%
higher than in non-noisy areas, after correction for
population characteristics. The difference was statistically
significant. The use of anti-asthmatic drugs, was
14% higher in areas close (<10km) to the airport, compared with areas further away. This was particularly
in children (0-19 years) and the
elderly (60+).
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E. EXTRA-AUDITORY HEALTH EFFECT.
3.18 Noise is a non-specific biological stressor. Much research has been done on a variety of factors.
3.19 Experiments on monkeys showed significant elevations of
both systolic and diastolic blood pressure
when exposed to noise at 85-90dB. These effects persisted long
after the noise was discontinued (19a,b). In
laboratory studies of humans exposed to noise increases of blood
pressure were seen (20). In individuals
exposed to noise, around Amsterdam (Schiphol) airport there was
an increase in the sale of
anti-hypertensive drugs (21). In children the blood pressure of
those in schools under the Los Angeles flight
path was higher than in those attending quiet schools (22). There
are some studies which do not show rises in
blood pressure. The most comprehensive recent review (12) which
takes into account the most recent
studies of occupational, transport, community, airport and
aircraft noise concludes that there is an association
between noise exposure and level of blood pressure, independent
of such factors as age, weight, smoking
etc. The studies have, however, been bedevilled by methodological
weaknesses; e.g. those with both raised
blood pressure and history of noise exposure are most likely to
move from noise affected areas.
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2. Effects on blood chemistry.
3.20 Most experiments and field studies show increased levels
of catecholamines, epinephrine and
norepinephrine (20). In studies in Caerphilly and Speedwell
individuals exposed to road traffic noise between
66 and 70dB (A), compared to those exposed to less than 55 dB(A),
had raised levels of glucose, white cell
count, plasma viscosity, total triglycerides and total
cholesterol(23).
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3.21 Although the various studies referred to above have shown
an effect of noise on the various risk factors
associated with the development of heart disease (myocardial
infarction) no study has yet, convincingly,
shown any rise in the incidence of heart disease. This is not
necessarily surprising since factors such as
smoking, weight, blood pressure, diet, cholesterol etc. have such
important effects. Although the contribution
of noise is likely to contribute to changes in the above
important risk factors it is very difficult to disentangle
the independent effect of noise.
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3.22 Higher mortality rates have been reported around Los
Angeles airport in areas with high noise levels,
compared to quieter areas (24,a,b). The authors estimated at
least a 5% increase in total deaths in the
population of 103,000 compared to the control of 91,000. The
excess in deaths was seen in all categories,
but particularly for suicide and amongst the elderly. The authors
caution that there is a rapid turnover of
residents in these areas - but it appears to be similar in both
the test and control groups. The test area was
within the 90dB(A) noise contour.
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3.23 That noise can affect human health by affecting the
immune system is based on a series of experiments
indicating that noise is a stressor (25) and studies that
indicate that stress of various kinds can influence
immune function (26). A review (27) which assesses 9 papers
published between 1988-93 concludes that
noise can damage the immune system.
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6. Pregnancy, Foetal development.
3.24 Several studies have shown an indication of reduced birth
weight, or an increase in premature births.
Although several studies have shown these effects, only one (28)
showed a statistically significant effect,
independent of other factors. Of equal concern was the finding
that the children of mothers exposed to sound
levels of 85dB(A) during work damaged the child's hearing.
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3.25 The evidence of the influence of noise on mental health
at the Glidewell Inquiry was inconclusive (para
5.9.1.- 5.9.4). Since that time the results of more studies have
become available. I do not intend to deal with
earlier studies of hospital admissions to mental hospitals around
airports, as these were available previously,
and found to be inconclusive. However, a very scholarly study has
recently been published (29). The study
conclusions are as follows:
3.26 "Noise, a prototypical environmental stressor, has
clear health effects in causing hearing loss but other
health effects are less evident. Noise exposure may lead to minor
emotional symptoms but the evidence of
elevated levels of aircraft noise leading to psychiatric hospital
admissions and psychiatric disorder in the
community is contradictory. Despite this there are well
documented associations between noise exposure
and changes in performance, sleep disturbance and emotional
reactions such as annoyance. Moreover,
annoyance is associated with both environmental noise level and
psychological and physical symptoms,
psychiatric disorder and use of health services. It seems likely
that existing psychiatric disorder contributes to
high levels of annoyance. However, there is also the possibility
that tendency to annoyance may be a risk
factor for psychiatric morbidity. Although noise level explains a
significant proportion of the variance in
annoyance, the other major factor, confirmed in many studies, is
subjective sensitivity to noise. Noise
sensitivity is also related to psychiatric disorder. The evidence
for noise sensitivity being a risk factor for
psychiatric disorder would be greater if it were a stable
personality characteristic, and preceded psychiatric
morbidity. The stability of noise sensitivity and whether it is
merely secondary to psychiatric disorder, or is a
risk factor for psychiatric disorder, as well as annoyance, is
examined in two studies in this monograph: a
six-year follow-up of a group of highly noise sensitive and low
noise sensitive women; and a longitudinal
study of depressed patients and matched control subjects
examining changes in noise sensitivity with
recovery from depression. A further dimension of noise effects
concerns the impact of noise on the
autonomic nervous system. Most physiological responses to noise
habituate rapidly but in some people
physiological responses persist. It is not clear whether this sub-sample
is also subjectively sensitive to noise
and whether failure to habituate to environmental noise may also
represent a biological indicator of
vulnerability to psychiatric disorder. In these studies noise
sensitivity was found to be moderately stable and
associated with current psychiatric disorder and a disposition to
negative affectivity. Noise sensitivity levels
did fall with recovery from depression but still remained high,
suggesting an underlying high level of noise
sensitivity. Noise sensitivity was related to higher tonic skin
conductance and heart rate and greater
defence/startle responses during noise exposure in the laboratory.
3.27 Noise sensitive people attend more to noises,
discriminate more between noises, find noises more
threatening and out of their control, react to, and adapt to
noises more slowly than less noise sensitive
people. Noise sensitivity through its association with greater
perception of environmental threat, its links with
negative affectivity and physiological arousal to noise may be an
indicator of vulnerability to minor psychiatric
disorder."
3.28 Stansfeld thus concludes that noise affects sleep by
delays in falling asleep, increase in heart rate, effect
on the EEG, diminished well-being and diminished sleep quality.
He considers that the meaning of noise to
the host is important and determines the reaction, e.g. the noise
of a baby crying after birth is a welcome
noise but aircraft noise is unwelcome. Those individuals
sensitive to noise have higher abnormal scores on a
questionnaire on psychiatric symptoms. There is no evidence of an
association of noise with psychiatric
disorders but there is a close relation between noise sensitivity
and psychiatric "caseness" (the liability to
develop psychiatric symptoms). Noise sensitivity leads to greater
annoyance and more psychiatric disorders.
No studies have yet been done on how to identify this sub-sample,
the effect on them in population studies is
masked by the lack of effect in others. He estimates that about
one third of the population are noise sensitive.
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4.1 There is now no doubt that noise influences health and
well-being. This paper documents the findings of a
series of research studies. I am not able to undertake as
comprehensive a review as the WHO (11), the
Dutch Institute of Public Health (12), or the United States
Administration (10). However, to demonstrate I
reproduce below (Attachment 1) a table from the Health Council of
the Netherlands (12) which reviewed
the findings of its National Institute. As I have indicated in
the text, all authorities, including the UK
government, accept the importance of controlling noise in the
environment, both to reduce its effect on
causing ill-health and to improve the quality of life. As with
all risk factors to health, there is no cut-off level at
which it can be stated that there is no harm below that level.
The higher the level of noise the greater the
damage. A variety of bodies have attempted to set "acceptable"
levels - from reviewing the literature it would
seem that most consider 35dBA to 45dBA appropriate. As other
HACAN evidence shows, noise levels
currently to the east of the airport, i.e. under the fixed flight
paths, have worsened considerably over the past
10 years. To allow them to deteriorate further, as most assuredly
they will if T5 is built, would not only be an
act of folly but also contrary to national and international
policy which is concerned with greater protection to
health than at present, and the improvement of the quality of
life. T5 proponents argue an economic case -
but omit in their cost-benefit statements the harm that would be
done, both to health, which has an
inestimable value, as well as to economic activity and
productivity, as shown by the effect of the studies on
sleep disturbance.
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CRITIQUE OF OLLERHEAD ET AL. (14)
A0.1 Recent UK policy on noise has been greatly influenced by
this study undertaken by the CAA. It is
remarkable how resistant the Department of Transport is to
concerns about its validity. This problem is not
unique. The USA has also become involved in such controversy
following the Expanded East Coast Plan, a
major east coast re-routing of metropolitan traffic into areas
not previously exposed, or in Sydney, Australia
with the building of a new runway. The problem is that in all our
societies noise has increased while at the
same time the public's expectations of a better environment and
improved quality of life has also increased.
A0.2 The problem with most policy-making in this arena is that
the effect of noise is complex, there is an
interplay of a multiplicity of systems while most studies rely on
the measurement of only a specific disease or
physiological variable. This implies that the research required
is far more complex, inter-disciplinary, and
must be carried out over a longer time-period. Unfortunately the
recognition of this need is only gradually
permeating into our policy-making.
A0.3 The Ollerhead study, as shown in the graph reproduced
from the Dutch report (12), is very different to
others, and the only one it resembles is that of Pearsons. The
latter should, however, be disregarded, as it
includes a variety of 21 studies. The Dutch comment that not only
were studies included in this analysis that
were inappropriate but also that Pearsons sometimes did not have
measures of the sound exposure level and
estimated them.
A0.4 Concerns with the Ollerhead study can be considered under the following headings.
A1. Site Selection
A1.1 The number of sites (2) for each airport are too few and
the levels of noise recorded and reported give
no indication of the variability both by time and by date (Final
Report, Table 4). Comparison of this table
with Figure 2, which shows higher noise levels 2 years earlier,
demonstrates the need for this.
A1.2 It is unsatisfactory to amalgamate findings at 4 airports.
There is a wide variation in the range of aircraft
noise exposure between airports. Although there are no intrinsic
geographic variations in sleeping behaviour,
there are geographic variations in social behaviour, such as time
of going to bed, time of last meal, type of
housing, furnishings etc. Thus the design and analysis chosen in
the Sleep Disturbance Study restricts the
variation of the effect of outdoor noise on individual subjects,
because it may be obscured by the variation in
exposure between the airports. In view of the small number of
sites, it is quite possible that the variation in
exposure to noise may be explained by between-airport variance
rather than the between-exposure variance.
Thus the choice of study sites actually restricts the variance in
noise exposure, and in turn the possibility of
drawing conclusions from outdoor noise levels from aircraft
activity.
A2. Subject Selection
A2.1 The method of selection of the individuals on whom
measurements were made is obscure.
Approximately 200 social survey interviews were undertaken for
each site and yet the number of addresses
listed is very different for each site - ranging from 669 to 397
(Table 2). It is difficult to understand how the
sample was drawn, what questions were asked, etc. In interpreting
any survey it is crucial that information is
given on precisely how the sample of subjects included at each
stage has been selected, the precise questions
asked by interviewers, and the instructions given to the
interviewers. This has never been disclosed, though it
has been stated that the subjects were not aware of the purpose
of the study.
A2.2 Of the 200 odd interviews at each site, approximately 50
volunteers were interviewed. It is quite
impossible to determine the criteria for these. To an
epidemiologist like me, the response rates are
horrendously low, and thus the population was highly selected. To
pick a final sample of 227 individuals on
whom measurements were made, out of an original 3,896 addresses,
is strange. This is a response of about
6 per cent. I am not aware of a public health decision made on
the basis of such a ludicrously small sample
chosen in such a curious way. Although the authors defend their
sample response, the following figures
demonstrate my concerns-
Original interview - 1,636 subjects (1 person per household).
Of these 1,636 subjects, 971 (59%)agreed to take part in the study.
Of these 971 subjects, 614 had a further interview (=37% of original sample).
Of these 614 subjects, 220 agreed to actimetry and EEG (=13%of
original sample, and =36% of those who
had a further interview).
50 of these subjects had both actimetry and EEG (=3% of original sample).
227 subjects agreed to actimetry only(=14% of original sample,
and =37% of those who had a further
interview).
A2.3 I am afraid that epidemiologists/public health physicians
would not be satisfied with such a low
response rate, whether from the initial or the subsequent
sampling. In the studies with which I am involved we
aim to achieve a response rate of at least 67%. In a recent study
of about 250,000 individuals in a mailed
survey (when one normally expects a lower response rate) we
obtained this level of response. In a private
census investigation in an inner city area of London, which
involved medical examinations, we achieved a
response rate of about 99% in a sample of about 10,000. These
examples illustrate how low the response
rate was in the current study, and therefore how unsatisfactory
it is to draw the conclusions that have been
drawn from it.
A2.4 It is known that susceptibility to noise is greater in
the elderly and in men. The objectives of the study
were stated to determine the relationship between aircraft noise
and the probability of sleep disturbance. It is
therefore curious that the young (under 50) and women are over-represented
in the sleep disturbance study
compared to those in the social survey.
A2.5 There were other exclusions which further upset the
sampling process. For example it was confined to
people who were available during the survey period, who were not
deaf (no objective measure of this was
made), who were not suffering from arthritis or rheumatism which
disrupts sleep, and who were not taking
(an undefined quantity of ) alcohol. In addition it is stated
that the 4.4% of subjects who were on hypnotics
(sleeping pills) were excluded: it is not defined whether these
were individuals taking such tablets daily or
only intermittently, and (as acknowledged in the paper at Tab Q (d),
page 10 by Horne et al, but not
suggested in the Final Report) of course it may have been that
such people were taking them to counteract
aircraft noise.
A2.6 In view of a previous study by the CAA (UK Aircraft Noise
Index Study: Main report. P. Brooker,
J.B. Critchley, D.J. Monkman and C. Richmond CAA, 1985) the lack
of concern with the characteristics of
the population is, to put it charitably, surprising. This 1985
study by SCPR, on behalf of the CAA, stated on
p.4 of the summary:
'A major "confounding factor", i.e. a social or
demographic variable which affects response (to aircraft
noise), is the proportion of people who work at or have business
with the airport: this has a very marked
effect on response, e.g. in some study areas their effect results
in an estimated lowering of 25% in the
percentage saying aircraft noise is "not acceptable".
Previous studies have not detected such a strong effect'.
Ollerhead et al. should not have omitted consideration of this
finding - in view of their response rate one
might question whether their population consisted largely of
airport employees.
A3. Interview Methods
A3.1 To a public health researcher of almost 40 years
experience it is curious that instructions or
explanations to participants are not available for scrutiny. It
is well known in epidemiological work that the
way questions are phrased, and the behaviour (even including
dress) of interviewers influences the responses
given. I have always been meticulous in making my documents
available.
A4. Individual Noise Exposure
A4.1 The relations between the noise monitor sites and the
individuals participating is not clarified. Although
it is stated that all houses were within the given 'noise contour'
- the validity of this statement has not been
checked by the investigators (It is also difficult to understand
in view of the fact that no such contours exist
for night time noise.) No checks have been made of the difference
in noise exposure in different houses. This
is particularly important in view of the different types of
houses in different areas.
A5. Arousal rates and window state
A5.1 The Final Report discusses the difference in arousal rate
between houses with single and double
windows.
A5.2 This is illustrated in Figure 56, which shows a clear
gradient for arousal between
open/shut/single/double windows in noisy compared with quiet
conditions. (The point is more obvious in
Figure 8.18 of the Final Draft Report, which shows the same
information, but uses a different projection in
the graphical presentation). The Final Report dismisses this as
"not being of statistical significance". It is
elementary in statistics to look at what figures and tables tell
you.
A6. Sample size
A6.1 Although it is stated that the pilot investigation
indicated that 50 subjects would be needed at each site,
the report nowhere states the rationale for this sample size.
Most investigations start off by determining the
effect to be identified. For example, if one was looking for a
difference in two populations where 50% of
subjects were woken in one population, and 0% were woken in the
other, the sample size would be much
smaller than if one were looking for a difference of say 40% in
one population and 30% in another. In
relation to aircraft noise, if one were willing to accept that 5%
of the population was woken at a noise level
of 75 dBA, the sample size would be greater than if one was
looking for an awakening rate of say 30% at
this noise level, because of the variability of waking at night.
Most statistics textbooks give tables of sample
size required to show a given effect. It is curious that the
investigators were so imprecise in this respect while
using very complex statistical equations for their analysis. They
seem to have neglected a basic rule in such
investigations.
A7. Noise, time and sleep disturbance correlation
A7.1 Both in the Final Report and a subsequent, unpublished
paper [Tab Q, (a)] the authors claim that there
is a threshold for noise disturbance, i.e. that people are only
disturbed if noise is above a certain level. It is
not surprising that they make this statement - even though it is
both counter-intuitive and different to that of
other studies - since they make no measurement below 75 dBA. In
fact their graph (Attachment 2) shows a
fall in arousal rate as noise increases from 75 dBA to 80 dBA - a
very curious finding - on which no
comment is made.
A7.2 The authors state (page 34 of the Final Report) that
"it is clear from this analysis that in general aircraft
noise has a negligible effect upon overall patterns of arousal
from sleep" while tables 7 (actimetry) and 4
(noise level) show a correlation. These conclusions are also
different from those of the November draft
report at page 26 -
"aircraft events with the highest noise levels, say
greater than 95dBA max, have a greater than average
chance of disturbing sleep, perhaps 50-100 per cent greater"
"Individual variations in noise sensitivity are important,
two or three per cent of people are more than twice
as likely to be disturbed by aircraft noise as the average person".
"At particular times of sleep i.e. during periods of
sleep lightenings, noise disturbance rates are around twice
the average".
A7.3 It is strange that this correlation is dismissed. The
tables show a higher average rate of actimetry activity
(which they correlate with awakening) in those areas with higher
noise levels. The variation is about 31%
(6.97 to 4.79) in actimetry. The noise exposures to aircraft Leq
are highest at this site (HGN); other noise
exposures are also higher at most times but not to the same
extent. The site with lowest mean actimetry
(SWM) also has lower aircraft Leq in Table 4 (there it is 64.2 at
HGN, and 49.6 at SWM, a difference of
23%). This cannot be dismissed and demonstrates the fallacy of
trying to amalgamate findings for different
airports. A far better analysis would be to examine the
variability between aircraft noise and sleep
disturbance at each airport individually.
A7.4 The Final Report summary states (page xiv, para 21)
"that sensitivity to aircraft noise seems to diminish
at the end of the nights' sleep". However page 23 of the
Final Report states "a major focus of the analysis has
therefore been to control for the powerful confounding effects of
individual variations in arousability". Pages
26 and 27 state that arousals are greater in the morning, yet
Ollerhead and Jones study (Tab Q, paper (a),
page 49) states that it "controls for time of night".
It is necessary to show that the time of night is related to
the probability of being disturbed in the absence of aircraft
noise, or at the very least that there is no
interaction between time of night and noise, otherwise one may
adjust out some of the effect of aircraft noise
in the early morning.
A8. Aims of the study
A8.1 The aims of the analysis, and thus the conclusions, are
confused. Were the authors concerned with
establishing the proportion of people affected by aircraft noise,
or at what levels of aircraft noise people are
affected? The authors describe between-subject variation - but
this is irrelevant, as one is only concerned
with the probability of a subject being disturbed relative to his
or her baseline level of disturbance at minimum
noise level. A within-subject analysis is required (and has not
been done) as it would not make assumptions
about how to describe between-subject variation. The essential
question is not the variation in arousal in a
population of different individuals in different areas exposed to
different levels of noise (between-subject
variation) but the variation in any single individual to being
aroused at different noise levels.
A9. Validation of actimetry
A9.1 The so-called objective method of sleep disturbance used
(wrist movements, actimetry) have been
validated against "sleep-EEG" (measurement of brain
activity). This validation is, however, very small, only 6
out of 50 subjects at each of 8 sites. The 6 "sleep-EEG"
cases were studied during 4 nights each, while the
50 actimeter cases were studied for 15 nights each. The
statistical, analytic base is thus very small
considering the large amount of intra- as well as inter-
variability of both EEG and actimetry. The results of
the validation are reported to be quite uncertain - that is 40 ±
10 per cent of the arousals actually represent
awakenings. As an epidemiologist concerned with the use of
physiological measurements in field situations on
many occasions I would not have accepted instruments of such low
validity. To explain this point, if any two
tests correlate on only 50% of occasions this implies that the
correlation can occur by chance. Thus the
results of the validation (Final Report, page 18) do not confirm
that they are any better than would occur by
chance.
A9.2 The approach of the study's authors, is that actimetry is
used because it is a "very efficient" way of
measuring arousals from sleep. It may be cost efficient, but that
is not the same as saying it is satisfactory
from a scientific point of view. It may be that it can be
validated to show that it is indeed a satisfactory
method. But, in the absence of that, it may be as or more 'efficient'
to rely on refinements to traditional
methods e.g. subjects keeping diaries of sleep disturbance. I
have specific experience (in the field of lung
disease) where, despite fears that it would not work, subjective
measurements turned out to be just as good
as objective measurement.
A9.3 It is very strange that the report does not examine what
seems the most curious finding that while on the
basis of actimetry only about 5 per cent of arousals are
attributed to aircraft noise, 23% stated that they had
been woken by noise. This is nearly five times more than the
actimetry studies suggest and therefore warrants
further investigation. Dr. Ollerhead says that the subjective and
objective findings are "not inconsistent". I do
not think it proper to disregard such a substantial difference.
A9.4 Thus the definition of sleep disturbance used in the
Final Report is incompatible with the operational
definition in terms of awakenings due to the low validity of the
actimeter measurement of wrist movements as
indicative of awakenings. The authors of the Final Report assume
that actimetry is a valid measure of
awakening. Yet in their comparison of actimetry and EEG, they
show a poor correlation. Further their
conclusions of awakening and response to a subjective
questionnaire (see above) are so different that one
wonders whether such a conclusion is valid.
A10. Conclusion
A10.1 These comments, I hope, illustrate the concerns I have
with what is purported to be the definitive
study by the CAA on the problem of aircraft noise. I enclose with
this paper (Attachment 3) a critique by a
Swedish scientist, Dr. B. Berglund, rapporteur of the WHO
committee concerned with noise and to which I
have referred (11). This makes similar, and other, comments on
the Ollerhead study.
A10.2 I am perplexed that a Government Department relies on
such an inadequate study for the formulation
of its policy. Fundamental to any assessment of any study
designed to determine policy are (1) the
impartiality of the investigation - this study was supported by
BAA and BA, and (2) that conclusions should
be supported by data and given unemotionally - neither criterion
is met. I am thus very concerned that the T5
Inquiry should obtain an independent view of the evidence and
take into account the views of other
Departments of State than Transport as well as the findings and
conclusions of other agencies and
governments.
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