🚀 go-pugleaf

As this subject is taboo for any government agency (we can't hurt the
airline industry you know)  to talk about, I thought I would post what
real doctors and researchers are doing on the Continent. Bill Mulcahy


HACAN
PROOF OF EVIDENCE
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

NOISE AND HEALTH

June 1997

HAC 61
PERSONAL DETAILS

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 M�dicine" 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.

1. SUMMARY

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.

2. INTRODUCTION
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.

3. EFFECTS OF NOISE

A. NOISE-INDUCED HEARING LOSS
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.

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)
2. Scholastic Performance.
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).
C. EFFECTS OF NOISE ON SLEEP
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.
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.
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..
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+).

E. EXTRA-AUDITORY HEALTH EFFECT.
3.18 Noise is a non-specific biological stressor. Much research has been
done on a variety of factors.
1. Effects on blood pressure.
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.
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).
3. Effects on Heart Disease.
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.
4. Total Mortality.
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.
5. Immunological Effects.
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.
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.
7. Mental Health.
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.

4. CONCLUSION.
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.
APPENDIX

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 disturbanceactimetry
activity (which they
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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--
Bill Mulcahy, member of Sane Aviation For Everyone
http://pages.prodigy.net/rockaway/safe.htm