Noise at night from airport and road traffic can increase blood pressure during sleep, according to a recent study.
The findings could give ammunition to opponents of noise pollution and proposed airport expansions, including at London's Heathrow, one of four European air hubs examined in the study.
The three others airports serve Athens, Stockholm and Milan. A team of European scientists led by Lars Jarup of Imperial College London monitored 140 sleeping volunteers in their homes near the airports, checking blood pressure every 15 minutes with remote devices. They found that a noise louder than 35 decibels - corresponding to a plane flying overhead or heavy vehicle traffic - provoked a spike in blood pressure.
Even a partner snoring loudly could produce the same effect, said the study, published in European Heart Journal, put out by the European Society of Cardiologists.
Study done outside of lab setting
"The short term effects of loud noise during sleep have been
documented in the laboratory settings, but not in populations living under normal conditions," said co-author Klea Katsouyanni, a researcher at the University of Athens Medical School.
People with high blood pressure - also called hypertension – have an increased risk of developing heart disease, stroke, kidney disease and dementia, previous research has shown. High blood pressure is defined by the World Health Organisation as
being 140/90 or more.
The first number measures maximum heart pressure (systolic), while the second measures pressure when the heart is in a resting phase (diastolic).
Aircraft noise caused an average increase of 6.2 in systolic blood pressure, and 7.4 for diastolic blood pressure. The figures for heavy road traffic were only slightly less.
Louder the noise, higher the blood pressure
The loudness, rather than the source, was the critical factor in boosting blood pressure, the researchers found. "We know that noise from air traffic can be a source of irritation, but our research shows that it can also be damaging for people's health," said epidemiologist Lars Jarup of Imperial College London.
Parallel findings by the same researchers to be published next month in the journal Environmental Health Perspectives, show that people who live under a busy flight path for at least five years are at greater risk of developing high blood pressure, Jarup said.
An increase in night-time aeroplane noise of 10 decibels, he said, enhanced the risk of high blood pressure by 14 percent in both men and women. The second study monitored 6 000 men and women. Both studies appear amid continuing controversy over a proposed new runway at Heathrow, one of the busiest international airports in the world.
The number of flights serving the airport are projected to expand from nearly half a million to 700 000 per year. In all, a couple of hundred people living near Heathrow could be affected by high noise levels, Jarup estimated.
Noise levels must be reduced
"It is clear that measures need to be taken to reduce noise levels from aircraft, in particular during night-time, in order to protect the health of people living near airports," he said.
The researchers, based in Athens, Stockholm, Milan and London, are currently investigating whether combined exposure to noise and air pollution increases the risk of heart disease. – (Sapa, February 2008)
Traffic fumes up heart risk
Sleep linked to blood pressure