Night noise guidelines for Europe - WHO/Europe - World Health ...

EFFECTS ON HEALTH
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Current evidence does seem to suggest that environmental noise exposure, especially at
higher levels, is related to mental health symptoms and possibly raised anxiety and
consumption of sedative medication, but there is little evidence that it has more serious
effects. Further research is needed on mental health effects at very high noise levels.
Existing studies may be confounded either by prior selection of subjects out of (or
into) noisy areas as a result of noise exposure, or by confounding between noise exposure,
socioeconomic deprivation, and psychiatric disorder. It is also possible that people
underestimate or minimize the effects of noise on health through optimism bias
(Hatfield and Soames Job, 2001) and that this is particularly protective for mental
health.
The evidence is not strong for the association between noise exposure and mental ill
health. What evidence there is suggests that noise exposure may be responsible for psychological
symptoms above 70 dB(A) L eq . Almost all studies have only examined the
effects of daytime noise on mental health, but it is possible that night-time noise, during
sleep time, may have effects on mental health at lower levels than daytime noise.
The most powerful evidence of noise on mental health comes from studies of military
aircraft noise. There is also some evidence that intense road traffic noise may lead to
psychological symptoms. There is no evidence of any effects of railway noise on mental
health.
4.9 THE SEVERITY OF SELF-REPORTED SLEEP
DISTURBANCE
4.9.1 INTRODUCTION
In section 2.1.2 of Chapter 2 of this report, it is stated that sleep disturbance caused
by noise may either be diagnosed (Environmental Sleep Disorder: ICSD 780-52-6) or
self-reported. Although self-reported sleep disturbance is subjective by definition, its
observed occurrence correlates with noise levels as well as with important diagnostic
criteria for ICSD 780-52-6. It appears justified to consider self-reported sleep disturbance
as an impairment of health, especially if indicated by representative population
samples in social surveys. Furthermore, section 4.1 of Chapter 4 of this report gives a
quantitative relationship between noise level L night and the percentage of population
that reports a disturbed sleep of high, medium or low disturbance intensity.
But an open question concerns severity: even if night-time noise causes large percentages
of the population to declare themselves as highly sleep-disturbed, this could nevertheless
represent an almost negligible loss of health, if the mean severity of self-reported
sleep disturbance were negligible in comparison with commonly accepted diseases.
Attempts have been made to give an answer to this important question, using WHO’s
concept of disability weights (Murray et al., 1996) as a basis for severity comparisons.
4.9.2 AN ASSESSMENT OF DISABILITY WEIGHTS
A Swiss study (Müller-Wenk, 2002) aimed at determining a disability weight for
sleep disturbance due to road traffic noise. For this purpose, a description of road-
NIGHT NOISE GUIDELINES FOR EUROPE