NOISE AND YOUR HEALTH
from a research paper submitted by SIU FONT and MARINA JOHNSTON
June 2008, at the age of 51, Dr. Sheela Basrur died of a rare
form of cancer. She was East York’s Medical Officer of
Health. She is best known for being the voice of health authority
during Toronto’s SARS crisis in 2003. She was appointed
Chief Medical Officer of Health for Ontario in 2004.
which is often referred to as unwanted sound, is typically characterized
by the intensity, frequency, periodicity (continuous or intermittent)
and duration of sound. Sound is the result of pressure changes
in the air caused by vibration. Unwanted sound to some may be
considered wanted sound by others, as in the case of loud music.
people are affected by noise exposure than any other environmental
stressor. However, because its associated health effects are
not as life-threatening as those for air, water and hazardous
waste, noise has been on the bottom of most environmental priority
much of the scientific evidence has been based on studies of
occupational exposures. These noise exposures tend to be of
greater intensity over longer periods of time as compared with
exposures to community noise. In earlier research, investigators
also tended to assume that noise produced direct health effects,
such as hearing loss with noise exposures above 90 decibels,
and paid little attention to individual differences in response
to noise, and noise as a stressor.
recently, research has focused on noise as an auditory stressor
that can produce both direct and indirect health effects. The
direct health effect known to be attributable to noise is hearing
loss (resulting from damage to the inner hair cells of the organ
of corti) with noise exposure higher than 90 decibels. There
are several non-auditory physiological effects of noise exposure
including a possible increase in cardiovascular disease from
elevated blood pressure and physiological reactions involving
the cardiovascular endocrine system. In addition, community
noise has been shown to adversely affect sleep, communication,
performance and behaviour, reading and memory acquisition, and
affects millions of people worldwide on a daily basis. Highway
noise alone affects more than 18 million people in the United
States and 100 million people worldwide. It is estimated that
community noise levels in the United States have increased over
11 % during the last decade, with aviation noise projected to
rise at an even more rapid rate. Most urban noise stems from
automobile traffic. Motor vehicle use worldwide continues to
climb despite campaigns to encourage reliance on public transportation.
Increasing population densities, especially in urban areas,
have also resulted in escalating noise levels. This has serious
impending health implications for all cities worldwide. Internationally,
the issue of noise is gaining more attention as countries set
their own national standards regarding noise control.
the Greater Toronto Area, it has been estimated that the population
will increase by 40% in the next 20 years and that automobile
ownership is estimated to increase by 60%. The expansion of
the Pearson Airport is currently being projected to increase
air traffic from approximately 27 million passengers to 50 million
passengers over the next decade. Further, the former City of
Toronto area is becoming known as a center for music festivals
on city streets, parks and public areas. This increase in public
leisure activities will likely add to noise levels in the city.
is evident that reducing noise levels in homes and the community
at large requires a multiplicity of actions by all levels of
government, the private sector and the general public. Within
the City of Toronto, the Public Health Division has a unique
role to play in reviewing the latest research on noise. This
information may assist city officials and the public in preventing
or reducing excess noise levels where reasonable and possible.
World Health Organization (WHO) defines “health as . .
. a state of complete physical, mental and social well-being.
Governments have responsibility for the health of their people
which can be fulfilled only by the provision of adequate health
and social measures.”
Canada, the Working Group on Environmental Noise of the Federal/Provincial
Advisory Committee on Environmental and Occupational Health
on the health costs associated with exposure to excessive noise
is limited. Research in Germany has estimated that the annual
cost of noise on public health is approximately $500 to $1900
million ECU (726.4 million dollars to 2.76 billion US dollars)
per year for road noise, and $100 million ECU (1.45 million
US dollars) per year for rail noise.
evidence that people show negative subjective responses to noise
(e.g., annoyance, dissatisfaction and disturbance) is strong.
However, there is no clear noise level threshold for measuring
community reaction. This is likely due to the considerable variation
in people’s tolerance to noise levels and the different
types of noise, making it difficult to quantify direct health
potential adverse health effects are usually classified according
to the type of noise. Sudden or impulsive noise appears to create
substantially more reaction than non-impulsive noise , and intermittent
noise has greater effect than louder, more continuous noise
. Predictability and controllability are clearly influencing
factors in individualreactions to noise.
physiological and psychological responses to noise are also
influenced by susceptibility. For example, noise sensitive people
attend more to noises, discriminate between noises, find more
noises threatening and out of their control, and react to, and
adapt to noises more slowly than less noise sensitive people.
There may be a small risk amongst some people that exposure
to the stress of high noise levels increases susceptibility
to disease and infection and can be a complicating factor in
heart problems and other diseases.
there are reasonable indicators of a casual connection between
noise exposure and health effects, the exact nature of this
causal relationship is not known. There is a relationship between
sleep loss and stress with possible causal connections in both
directions. It is less understood how reaction modifiers, including
attitude to the noise source, noise sensitivity, and perceived
control over the noise consciously or unconsciously influence
an individual’s reaction to noise
HEALTH EFFECTS RELATED TO NOISE
Loss. The evidence for a cause-effect relationship between
noise and hearing loss is considered sufficient in the scientific
community. There is consensus that sound levels less than 75
dB(A) are unlikely to cause permanent hearing loss and that
sound levels about 85 dB(A) with exposures of eight hours per
day will produce permanent hearing loss after many years.
Annoyance can be defined as “the expression of negative
feelings resulting from interference with activities, as well
as disruption of one’s peace of mind and the enjoyment
of one’s environment.” Evidence has shown that unexpected
or impulse noise is more annoying than continuous noise of equivalent
in the workplace has been studied and may yield useful insights
into annoyance caused by ambient urban noise. The Health Council
of the Netherlands found no association between noise level
in the workplace and annoyance. The Council, however, identified
five non-acoustic variables that have a greater effect on annoyance
than noise level: meaningfulness and information content of
the noise; predictability, avoidability, and controllability
of the noise; attitude of workers to the noise; task demand;
cardiovascular effects have been extensively studied in occupational
settings. The Health Council of the Netherlands concluded that
prolonged exposure to occupational noise may contribute to increased
blood pressure and hypertension. These effects were shown to
occur at sound levels of 85 dB(A). Other noise-induced cardiovascular
effects include: abnormalities in the electrocardiogram; more
heart beat irregularities; faster pulse rate; and slower recovery
of vascular constriction.
has been more difficult to determine the effects of noise in
the urban environment. Most studies have focused on the effects
of air and road traffic noise on people in their own homes.
A complicating factor has been to distinguish exposure to traffic
noise versus other, often even louder noises, from other sources.
Housing features, as well as personal habits and proximity of
sleep areas to the noise source (e.g., road) affect the actual
noise exposure. There is some evidence that suggests an increased
risk of hypertension and ischaemic heart disease for people
living in areas with road or air traffic noise at outdoor equivalent
sound levels above 70 dB(A)based on exposure between 6:00 a.m.
and 10:00 p.m.
studies have found that kindergarten children had significantly
higher systolic and diastolic blood pressures when exposed to
noisy or very noisy environments (kindergarten and home) as
compared to quiet environments. However, these effects appear
to be of temporary nature.
Disturbance. Noise has been reported to lessen the quality
and the duration of sleep. Epidemiological studies have focused
on the impact of noise on individuals such as patients in hospital
and the impact of particular sources of noise (e.g., aircraft)
on sleep. The Health Council of the Netherlands has considered
the evidence to be sufficient for a causal relationship between
the long-term effects of noise-related sleep disturbances, with
changes in sleep patterns, awakening, sleep stages, and subjective
sleep quality. Susceptible persons may be affected by noise
occurring during sleep, as well as the waking state, with day
and night noise being a significant problem for night workers,
mothers with babies, elderly persons, persons who are especially
vulnerable to physical or mental disorders, and other individuals
who experience sleeping difficulty.
Effects. There appears to be an association between sleep
and the immune response. Thus, it would follow that further
study is required on the immune responses of people exposed
to noise during sleep, especially those exposed to intermittent
transportation noise. For example, nocturnal noise has been
indicated as a health risk because of the disturbance to the
distribution of sleep stages resulting in direct immuno-suppressive
effects, specifically inhibition of eosinophils and basophils
which usually proliferate during sleep.
Caerphilly and Speedwell Study found an increased concentration
of leucocytes in the blood of persons exposed to high levels
of traffic noise. Although no studies have reported a causal
relationship between noise and compromised immunity, increased
concentration of leucocytes in blood might lead to increased
prevalence of diseases such as influenza.
Effects. Noise-induced biochemical changes (specific hormones
and metal ions such as magnesium) have been found in persons
exposed to very high environmental or occupational noise, suggesting
noise acts as a stressor. Several studies also show biochemical
changes indicating an increased risk of ischaemic disease. However,
limited data on the causal relationship is currently available.
Effects. There is limited evidence to suggest a relationship
between air traffic noise exposure of pregnant women in the
living environment and low birthweight. There is virtually no
data to suggest an increased risk of congenital anomolies.
Effects. Very little research has focused on the effect
of noise on human productivity in community situations. Most
studies have occurred in the laboratory and work settings. Noise
has been shown in test subjects to increase alertness, affect
task strategy, and decrease attention to the task. Performance
on simple tasks, however, especially those that are monotonous,
may actually be improved by noise, presumably by elevating the
subject’s alertness. There are consistent after-effects
of noise on tasks requiring higher cognitive performance (e.g.,
proofreading, completing a puzzle). Some accidents may also
be a result of the effects of noise on performance.
Groups. There may be some populations at greater risk for
the harmful effects of noise. These groups include: the elderly,
those with a mental health disorder, the blind, possibly fetuses,
and young children. For example, children appear to be particularly
susceptible to noise-induced health effects including: interference
with speech acquisition and language development (which can
create frustration and impair social interaction), inattention
and impaired task performance, lower reading scores, and delayed
motor reflex reactions. According to Berglund and Lindvall,
classrooms and day care facilities often surpass the recommended
sound pressure level (e.g., 35 dB(A) during teaching sessions),
compromising the optimum learning environment for children.
For hearing impaired children, it is suggested that the sound
level needs to be even lower.
and young adults appear to be at greater risk for noise-induced
hearing loss due to their exposure to very high levels of noise
during leisure activities including concerts and bars, use of
personal cassette players, car stereos, firearms (including
pellet guns and toy cap guns), fireworks, arcade games and motor
sports such as racing cars.
Health Council of the Netherlands suggests that susceptible
populations to the adverse health effects of noise can also
include: people that are highly annoyed by low levels of road
traffic noise (for hypertension); men exposed to high levels
of road traffic noise at home as well as occupational noise
(for ischaemic heart disease); and pregnant women who are exposed
to occupational noise (for hypertension). Further, people with
sleep disturbances have an increased risk of hypertension and
ischaemic heart disease compared to people who live in the same
environment that do not experience sleep disturbance. Finally,
exposure of hospitalized patients to relatively high levels
of noise from sources inside or outside the hospital delays
recovery and wound healing.
is an important health issue that affects more than hearing.
The scientific research demonstrates that health effects occur
at noise levels below those that impair hearing. Some of these
health effects include increased risk for cardiovascular disease,
negative effects on sleep, communication, performance and behaviour,
reading and memory acquisition, and mental health.
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