International Journal of Environmental Protection Jan. 2016, Vol. 6 Iss. 1, PP. 15-46
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DOI:10.5963/IJEP0601003
Health Impairments, Annoyance and Learning
Disorders Caused by Aircraft Noise
Synopsis of the State of Current Noise Research
Martin Kaltenbach
*1
, Christian Maschke
2
, Franziska Heß
3
, Hildegard Niemann
4
, Martin Führ
5
1
Prof. Dr. med. Martin Kaltenbach former Dir. Cardiology, University Hospital Frankfurt, Germany
2
Dr.-Ing. habil Christian Maschke, Head of division aircraft noise, Office for the Environment, Public Health and Consumer
Protection, Potsdam, Germany
3
Franziska Hess, specialist lawyer for administrative law, law firm Baumann, Leipzig, Germany
4
Dr. Hildegard Niemann former executive board, Innovation Center Technologies for Health and Foods (IGE), Technical
University Berlin, Germany
5
Prof. Dr. Martin Führ, Professorship of environmental law, University of applied sciences Darmstadt, Germany
*1
martinkaltenbach@arcor.de;
2
christian.maschke@lugv.brandenburg.de;
3
hess@baumann-rechtsanwaelte.de;
4
hildegard.niemann@tu-berlin.de;
5
martin.fuehr@h-da.de
Abstract- The article reviews the results of scientific research on aircraft noise induced health impairments, annoyance as well as
learning disorders and summarizes consequences for legislative and political decisions. The association of noise with an increased
incidence of chronic arterial hypertension has been shown in large-scale epidemiological studies. Identified risks are up to 20% per
10 dB increase in day-evening-night level (above 50 dB(A)) and for nightly noise exposure within a range of 19-34% per 10 dB
(above 30-35dB(A)). Identified risks regarding the use of antihypertensive drugs are partly higher. Also an increase in strokes is
documented in recent epidemiological studies and understood as a consequence of hypertension. The same applies in the case of
heart failure. Likewise an increase in myocardial infarctions has been confirmed in the recent studies with large populations
included. Moreover, the annoyance due to aircraft noise has been significantly underestimated in the last 15 years. Compared to the
EU-position paper of 2002 the sound level at a given extent of annoyance (25% HA) is at least 10 dB(A) lower. Impairments of
cognitive performance in children attending schools exposed to high aircraft noise have been demonstrated in national and
international studies up to the year 2014. As consequence of the present knowledge in noise effect research legal and political
decisions must form the base to reduce aircraft noise exposure during the 24h-day to L
den
= 50 and during the night to L
n
= 45 dB(A).
Keywords- Noise Research; Hypertension; Myocardial Infarction; Stroke; Health Impairments; Annoyance; Learning Disorders
I. INTRODUCTION
Several review articles on noise effects were published during the last decade [1-10]. Generally these prior studies are
focused on only one aspect like hearing impairments, health impairments, annoyance, sleep disturbances or learning disorders.
Hearing impairment due to noise may occur in the form of damage to the inner ear starting from an equivalent continuous
sound level of 80 dB(A), or at peak levels above L
peak
=140 dB(A) [11]. In the case of air traffic, such high noise exposures do
not arise in residential areas usually.
An increase in the incidence of chronic hypertension due to noise has been described in many studies beginning in 1968
and continued up to today [12, 13]. Myocardial infarctions may occur as a result of chronic hypertension. Beyond that, stress is
discussed as a risk factor. The impairment of vascular reactions during (simulated) air traffic noise may constitute a link
toward the genesis of arteriosclerotic lesions [14]. Hence, a positive relationship appears plausible, and the association was
repeatedly documented in large scale studies with statistical significance. In addition chronic high blood pressure is also a
predominant risk factor for strokes. Beyond the positive association in recent studies a causal relationship between noise
exposure and increased occurrence of stroke is therefore plausible. This also applies to heart failure.
An increased incidence of depression as a result of noise has been described by several authors [6, 15-17]. A link between
the occurrence of depression is plausible, if depression is recognized as “a process related with a feeling of hopelessness and
helplessness” [18]. Thus high levels of aircraft noise can be seen as typical for causing a depression in people suffering from
noise and in particular if they are being unable to leave their homes.
Noise annoyance is one of the best-documented noise effects. The continuous sound level at a given extent of annoyance
has markedly dropped within the last years (e.g. [19]). From 1960 to 1995 a reduction of approximately 8 dB(A) was measured
[20]. Up to 2011 the limit of annoyance has further dropped by an additional 8 dB(A). Noise-related annoyance is associated
with sleep disorders, “negative emotional reactions”, “vegetative-hormonal regulation disorders” and with increased risks of
illness [21 - 23].
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DOI:10.5963/IJEP0601003
The strength of noise-induced sleep disturbances is dependent on the intensity and number of acoustic stimuli, and their
structure over time, as well as on the stage of sleep of the affected person, and on the information hidden in the noise.
Sufficient undisturbed sleep is a biological necessity for humans, and long-term disturbed sleep is a health hazard [6]. Night-
time aircraft is therefore the most dangerous form of noise exposure.
Performance deterioration as a result of noise is familiar to everyone. It is one of the most common causes of complaints
regarding the effects of noise. All mental performance and physical activities that require special mental control can be
detrimentally affected by noise [24]. Accordingly, childhood learning disorders as a result of aircraft noise may be expected at
schools or homes [25]. An important unresolved question regarding noise-related learning disorders in children is whether it
constitutes a temporary restriction of learning abilities, which can later be recovered, or it represents permanent damage.
II.
ACOUSTICS AND THE SPECIAL CHARACTER OF AIRCRAFT NOISE
A. How can noise exposure, including aircraft noise, be measured?
In order to describe noise impacts objectively and to compare them, defined acoustic parameters are required. The unit for
measuring sound pressure levels is the “decibel” (dB). When directly describing two sounds, a level difference of
approximately 1 dB is barely perceptible. Sounds consist of various frequency components. The unit for measuring frequencies
is “Hertz” (1 Hz = 1 oscillation/s). To describe the effect on humans by means of the sound pressure level, that level must be
adapted to the human auditory capacity. That is accomplished by means of a standardized frequency weighting (A-weighted).
This “hearing-related” frequency weighting is represented in formulas with the indicator A, or in connection with acoustic
measurement values as dB(A), where A stands for auriculum, the ear.
Usually environmental noises are not constant, but rather change over time. The most important measure for fluctuating
noise over time is the equivalent continuous sound level (L
Aeq
) (cf. [26]) or average sound level (L
m
). This continuous sound
level is the level of a (theoretical) continuous sound with the same acoustic energy as the same sound fluctuating over time.
Accordingly, the continuous sound level is a single digit value, which exclusively describes the effect of a noise situation in the
period of time to be assessed, but which cannot be heard.
The equivalent continuous sound level is, as a rule, insufficient to comprehensively describe the noise’s effect on humans.
Beyond tonality, the impulsiveness of the sound and the increased sensitivity of humans during the evening hours must be
taken into account. These effects are accounted for by means of standard adjustments.
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
5
%
6
%
7
%
8%
9%
1
0
%
1
1
%
1
2
%
13
%
14
%
1
5
%
1
6
%
1
7
%
1
8
%
1
9
%
2
0
%
Night-time air traffic share
Sound level difference in decibel
Ldn-Leq,16hrs
Lden-Leq,16hrs
FBN - Leq,16hrs
Lden - Ldn
Fig. 1 Sound level differences between L
den
, FBN, L
dn
and L
Aeq,16hr
(y-axis), depending on the night-time air traffic shares (x-axis). Equal day-time and
night-time aircraft mixes: the noise level during the 4-hr or 3-hr evening period corresponds to the noise level for the 12-hr day (without adjustments). The
diagram indicates for example that the L
den
is approximately 1dB higher than the L
dn
with a night-time air traffic share of 8%.
Acoustic parameters for measuring and comparing air traffic noise exposure include day-night levels (L
dn
), day-evening-
night levels (L
den
) (supplemented by L
night
), and the noise rating level (L
r
) for a 16-hr day and an 8-hr night. The matter is
complicated by the fact that day-night levels (L
dn
) and day-evening-night levels (L
den
, FBN
1
) cannot simply be converted to
1
FBN is a Swedish 24 h aircraft noise level
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DOI:10.5963/IJEP0601003
one another, or recalculated as rating levels (L
r
) for day-time and night-time hours. The required acoustical information is
usually lacking, so comparing the acoustic parameters is possible only by means of estimates. Such estimates can be
undertaken for example on the basis of night-time air traffic share estimates (see Fig. 1) and used in section 4.
The statement of continuous sound levels (with adjustments), lacks information about the structure of the sound over time.
This could be a problem for such a strongly intermittent noise as it is aircraft noise, particularly for the night time (cf. section
4).
Aircraft noise is generally calculated with acceptable approximations to the measured values such as the integrated noise
model, or the German Aircraft Noise Protection Procedure [27]. The calculation errors for continuous sound levels in the
vicinity of airports are in general no greater than the errors occurring in measurement procedures.
B. Protection against aircraft noise
Road and rail traffic protection often consists of noise barriers, built between the noise sources and the recipients. Air
traffic protection by shielding devices is usually not possible, since aircraft noise comes from above and contains a high
proportion of low frequency sound which is poorly damped by walls. Noise-reducing measures on aircrafts in the past have
been overcompensated by the increase of aircraft movements and the use of bigger aircraft (cf. e.g. [28]). Changes in traffic
procedures simply redistribute aircraft noise. Noise-reducing flight procedures like continuous descent arrivals or steeper
landing approaches can be applied only to a limited extent, due to flight capacity restrictions. The use of super-insulating noise
protection windows in buildings and usage of ear protectors may be helpful. However, these options create considerable
discomfort for many people. If windows are kept closed, ventilation units are required to avoid excessive CO
2
concentrations
[29]. The installation of decentralized air supply devices is only appropriate if controlled exhaust ventilation is performed as
part of a ventilation planning system, and if thermal comfort criteria are taken into account in the installation process (cf. e.g.
[30]).
C. The effect of aircraft noise compared with other traffic related noise sources
Despite equal sound levels, there are considerable differences with regard to the effect of various traffic noise sources. This
has been shown by comparing annoyance or sleep disturbance caused by aircraft noise with the annoyance or sleep disturbance
caused by road traffic and rail noise. On basis of the same sound level, aircraft noise yields the highest level of annoyance or
sleep disturbance, rail traffic noise the lowest, while road traffic noise is in between. Moreover, with regard to air traffic noise
recent investigations have shown higher annoyance or sleep disturbance levels than those shown in older investigations [31].
The following Fig. 2 and Fig. 3 show the exposure-response relationships of the European Commission (EU curves) [32] and
the Night Noise Guidelines of the World Health Organisation (WHO) [6].
air traffic
0
10
20
30
40
50
60
40 50 60 70 80
L
DEN
(outside, most exposed
facade) [dB(A)]
% highly annoyed
road traffic
0
10
20
30
40
50
60
40 50 60 70 80
L
DEN
(outside, most exposed
facade) [dB(A)]
% highly annoyeded
rail traffic
0
10
20
30
40
50
60
40 50 60 70 80
L
DEN
(outside, most exposed
facade) [dB(A)]
% highly annoyed
Fig. 2 Annoyance: The exposure-response relationships for highly annoyed persons (in %), with reference to day-evening-night levels (L
den
), for the façade
most highly exposed to aircraft noise (left panel), road traffic (middle panel) and rail traffic (right panel) (from [32]). For air traffic, an exposure-response
relationship has also been added, shown by a dotted line, which only takes the latest studies into account, i.e. those published between 1996 and 2006 (from
[31])
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DOI:10.5963/IJEP0601003
air traffic
0
10
20
30
40
50
60
35 45 55 65 75
L
night
(outside, most exposed
facade) [dB(A)]
% highly sleep disturbed
road traffic
0
10
20
30
40
50
60
35 45 55 65 75
L
night
(outside, most exposed
facade) [dB(A)]
% highly sleep disturbed
rail traffic
0
10
20
30
40
50
60
35 45 55 65 75
L
night
(outside, most exposed
facade) [dB(A)]
% highly sleep disturbed
Fig. 3 Sleep disturbance: The exposure-response relationships for self-reported highly sleep-disturbed persons (in %), with reference to day-evening-night
levels (L
den
), for the façade most highly exposed to aircraft noise (left panel), road traffic (middle panel) and rail traffic (right panel) according to WHO [6]).
For air traffic, an exposure-response relationship has also been added, shown by a dotted line, which only takes the latest studies into account, i.e. those
published between 1996 and 2006 (from [31])
The exposure-response relationships depicted in Figs. 2 and 3 (solid lines) show that aircraft noise cannot be equated with
road noise – or rail noise – in regard to noise effects.
III.
SYSTEMATIC EVALUATIONS OF STUDIES
A. General considerations
Noise effects on annoyance, health and cognitive performance must be evaluated by assessing the results of
epidemiological studies of the population. Experimental investigations are taken into account particularly in regard to
pathophysiological mechanisms. The direct transformation of laboratory experimental results into practice is not possible
because many conditions, contributing to noise effects in real life, cannot be simulated in the laboratory and health
impairments may only emerge after years of exposure.
Statistical results from epidemiological studies are expressed as relative risk (RR) or odds ratio (OR). A relative risk with a
value greater than 1, indicates a positive association between the examined risk factor, for example noise exposure, and a
health endpoint. A statistically significantly increased risk exists, when the confidence interval (95% CI) of the RR does not
enclose the value 1. By means of advanced statistical techniques only the OR can be calculated. OR and RR are similar, when
the probability to fall ill is low. This is mostly valid for environmental risk factors.
Investigations exploring the effects of civilian aircraft noise on humans published between 2000 and 2014 were assessed.
Searches were conducted in the databases of German Institute of Medical Documentation and Information (DIMDI) and
PubMed, using the keywords “annoyance”, “cardiovascular disease”,“hypertension”, “high blood pressure”, “myocardial
infarction”, “stroke”, “depression”, “cognitive performance”, and “reading ability” each in combination with “noise”, in both
German and English, and were supplemented by the literature listed in references of relevant articles and by the literature of
the authors. We focused on epidemiological studies, but also used other investigations in the case that they represent basic
research or may contribute to understand epidemiological findings. Relevant articles that were published while the overview
work originated were additionally included. Excluded were studies with the terms “occupational”,“work” and “tinnitus”. In a
further step, studies were excluded which evidently had no relevance to the issues at hand, or which, due to their design
(information value), or size (avoidance of random errors) were not considered useful. Care was take to include all
investigations with negative results.
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B. Hypertension
Pathophysiologically, noise-induced hypertension is attributed to disturbance of the resting process. If the capacity for
coping is exhausted, a permanent increase in blood pressure results. Hypertension-related disease as a result of chronic noise
stress often occurs only after five to 15 years of exposure [12, 33]. Chronic arterial hypertension affects a large part of the
population, and is an important risk factor for heart attacks and strokes [34]. Since arterial hypertension is a mass endemic
disorder, even an increase or decrease by a few percentage points is of major practical significance.
In 2001, from an examination of aircraft noise exposure to 2959 adults (response rate: >70%), Rosenlund found a
significant relation (OR 1.6 95% CI 1.0-2.5) between increased hypertension and the Swedish day-evening-night level (FBN)
over 55 dB(A), and maximum levels over 72 dB(A) around Stockholm’s Arlanda Airport [35].
A Swedish investigation by Öhrström et al. showed a close association between noise level, hypertension and the increased
administration of blood-pressure reducing medications [36]. A random sample of 1953 test persons aged 18 to 75 with a
response rate of 71% was examined. All test persons were exposed to a traffic-induced continuous sound level (road, rail,
aircraft) of at least 45 dB(A) over the course of 24 hours. Aircraft noise exposure (L
eq
,
24hr
= 45-70dB(A)) was established with
address precision by means of GIS technology, and compared with surveyed medicinal endpoints. For men, the results yielded
uniformly increased exposure-response diagnoses, both for hypertension and for anti-hypertension medication intake. Among
the hypertension diagnoses, the first significant level class (upcoming from the lowest class) was ascertained at L
eq
,
24hr
= 60-70
dB(A) (OR 4.0 95% CI 1.3 -13); for anti-hypertension medications, it was at L
eq
,
24hr
= 55-60 dB(A) (OR 2.7 95% CI 1.1 – 6.6).
It should be noted that the upper level classes contain few cases in this partial assessment.
Increased administration of medications associated with aircraft noise exposure, was also found by a Dutch investigation
with more than 11,000 participants (response rate: 39%). In this study, the exposure was established only approximately on the
basis of postal codes [37]. The clearest increase in use involved the day-evening-night level, which may, in part, be due to the
fact that night-time flight operations are legally restricted in Amsterdam.
The most extensive study on the administration of medications was carried out in the areas surrounding the Cologne-Bonn
Airport. Here, health insurance data of 809,379 insured individuals exposed to both aircraft and road traffic noise was collected
address-precise, using GIS technology [38]. The study yielded significant relationships between the intensity of aircraft noise
and the amount of blood pressure reducing medications prescribed per patient. Medication prescriptions correlated most
significantly with night-time air traffic between 3 AM and 5 AM, the time period when the greatest night-time air traffic noise
exposure occurs at that airport. Blood pressure reducing medications prescribed for women during this time window increased
significantly, by 29%, even at an aircraft noise induced continuous sound level of between 40 and 43 dB(A), and by 48% in the
level range of between 48 and 61 dB(A). For men, the increase in prescriptions was 12% at a continuous sound level of 40 to
43 dB(A), and 32% at 48 to 61 dB(A) [39].
Fig. 4 Relative Risks of hypertension for men in Stockholm in relation to aircraft noise (FBN). Adjusted for age and BMI. The error bars denote 95% CIs for
the categorical analysis [41]
With respect to the early stages of hypertension, time-series study in the area surrounding Frankfurt Airport showed that
even in the physiological blood pressure range, a relationship exists between aircraft noise and early-morning blood pressure
[40]. Two groups were followed over a period of three months. They were exposed to night-time outdoor aircraft noise of 50