A team of international experts looked at all major studies conducted on the topic of noise and health, particularly those completed within the past five years, and concluded that constant noise — defined as unwanted sound — is associated with several non-hearing-related health effects, including heart disease, sleep disturbances and learning problems in children.
Noise “is a pollutant whose effects on health have been neglected,” the experts declare in the article.
Yet, that situation seems to be changing. In recent, years, an increasing number of researchers have begun to investigate the non-hearing-loss-related effects of environmental noise exposure on public health. (Environmental noise is that caused by road, rail and air traffic and by building and other types of construction.)
What they’re finding isn’t definitive, but neither is it reassuring, especially given that, as the authors of the current review article note, “noise is pervasive in urban environments and the availability of quiet places is decreasing.”
An association with heart disease
The most common response that people have to environmental noise is annoyance, explain the reviewers.
But annoyance isn’t a minor matter from a health perspective, they quickly add.
“Noise annoyance can result from noise interfering with daily activities, feelings, thoughts, sleep, or rest, and might be accompanied by negative responses, such as anger, displeasure, exhaustion, and by stress-related symptoms,” the reviewers write.
In other words, it can have a very real effect on wellbeing and health.
Research has repeatedly found, the reviewers point out, that chronic exposure to noise raises blood pressure, speeds up the heart rate and releases stress hormones — all factors associated with an increased risk of heart disease.
Indeed, as I reported here in October, two recent studies found an association between chronic exposure to high levels of airplane noise and an increased risk of developing cardiovascular disease, particularly for older people.
A disturber of sleep
The observed association between chronic environmental noise and heart disease may be linked to the disruptive effect that such noise has on sleep.
In fact, some epidemiological studies suggest, according to the authors of the review article, that nighttime exposure to chronic noise may be a more of a potential factor in heart-related health problems than daytime exposure.
Noise can be disruptive, by the way, even if it doesn’t cause people to wake up during the night.
“Repeated noise-induced arousals interfere with sleep quality through changes in sleep structure, which include delayed sleep onset and early awakenings, reduce deep (slow-wave) and rapid eye movement sleep, and an increase in time spent awake and in superficial sleep stages,” the reviewers write.
An inhibitor of learning
Research has also found an association between high levels of environmental noise and children’s cognitive performance.
“More than 20 studies have shown environmental noise exposure has a negative effect on children’s learning outcomes and cognitive performance, and that children with chronic aircraft, road traffic, or rail noise exposure at school have poorer reading ability, memory, and performance on national standardized tests than do children who are not exposed to noise at school,” the reviewers point out.
Studies that have observed children before and after their exposure to noise was minimized or eliminated (by the insulation of buildings or the closing down of airports) found improvements in cognition. This finding suggests, write the reviewers, that “noise reduction can eliminate noise effects on cognition.”
Caveats and a call for better studies
All the studies used in this review come, however, with major caveats — ones that the reviewers acknowledge. The research done to date has been primarily observational, which means it can show only a correlation between two things (chronic noise and health problems), not a cause-and-effect. Other factors that have nothing to do with noise could also explain the studies’ findings.
For example, areas with high levels of environmental noise are often home to families who are economically deprived, and such deprivation is known to affect children’s ability to learn and do well on standardized tests.
In addition, noise pollution, whether from cars or construction, is often accompanied by air pollution, which is also associated with an increased risk of heart disease.
Still, the reviewers believe that the evidence to date is strong enough to require public action.
The “non-auditory health effects of environmental noise are manifold, serious and, because of the widespread exposure, very prevalent,” they conclude. “These factors stress the need to regulate and reduce environmental noise exposure (ideally at the source) and to enforce exposure limits to mitigate negative health consequences of chronic exposure to environmental noise.”
Unfortunately, only an abstract of the review article is available on The Lancet website.