Environmental Engineering Reference
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risk of arteriosclerosis (hardening of the arteries) and myocardial infarction (death of
a portion of the heart muscle due to loss of blood supply) (Ising et al, 1999).
Ising et al (1999) contend that noise is an important risk factor in cardiovascular
disease, especially myocardial infarction. They envisage that chronic noise-induced
stress accelerates the ageing of the myocardium, increasing the risk of infarct. The
suggested mechanism is via increased stress hormones (catecholamines and cortisol)
and an interaction with intracellular calcium and magnesium ion shifts. However,
this is based partly upon animal studies, which have not always proved directly com-
parable to the situation in humans. Spreng (2000a, 2000b) studied the complex mech-
anisms involved in central nervous system activation by noise and suggests that chronic
noise can lead to long-lasting activation of the HPA axis, which leads to disturbed
hormonal balance and disease (eg immuno-suppression, diabetes, cardiovascular dis-
ease, osteoporosis and ulcers).
Important questions remain about the precise mechanisms or pathways by which
environmental factors, such as noise, influence health outcomes (morbidity and mor-
tality). Evidence of an increased risk of hypertension due to environmental noise is
limited (Babisch, 1998). Babisch (2000), reviewing the potential links between traffic
noise and cardiovascular disease, points out the limited number of epidemiological
studies between traffic noise and cardiovascular disease, with no evidence of a relation-
ship between noise exposure and blood pressure in adults. In children, noise-related
rises in blood pressure have been found (Morrell et al, 1997). There is some evidence
for an increased risk of ischaemic heart disease for subjects who live in noisy areas
with outdoor levels greater than 65-70dB(A) (Berglund and Lindvall, 1995).
Stansfield et al (2000), reviewing the impact of environmental noise on mental
health, found some evidence that exposure to high levels of environmental noise are
associated with mental health symptoms and, possibly, raised anxiety and consump-
tion of sedative medication, but little evidence of more serious effects. Several stud-
ies have reported no interaction between self-reported noise sensitivity and noise
exposure to an increased vulnerability to mental ill health. Children exposed to chronic
aircraft noise were not more susceptible to depression or anxiety despite having a
reduced quality of life. These authors identified a need for more accurate and detailed
noise measurement; careful consideration of other environmental stresses and con-
founding factors (eg socio-economic status); avoiding target communities where
noise-sensitive individuals had moved away; and a wider use of standardized instru-
ments to measure mental health outcomes and other related physiological outcomes,
such as hormonal levels.
There are certain groups who are particularly vulnerable to the effects of environ-
mental noise. For instance, Morrell et al (1997) indicated that annoyance reactions
are greater in people who fear aircraft crashes. Patients in hospitals are also more vul-
nerable to noise. Children are also thought to be a particularly vulnerable group as it
is believed that they are more susceptible to noise-induced hearing loss than adults.
In conclusion, it can be said that aviation noise has a number of health implica-
tions, both physiological and psychological. However, it can be seen that much of
the research in this area is either inconclusive or contradictory. This is probably because
there has not been sufficient expertise focused in this specialized area of environmen-
tal health, which will need to expand further in order to clarify some of the complex
issues remaining. Generally, aviation does not pose a significant risk to the majority
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