Noise pollution from traffic is emerging as an increasingly acute threat to health, and new research shows that even moderate road traffic noise can affect the heart and circulatory system after just one night.
For a study published last month in the journal Cardiovascular Research, researchers in Germany simulated different situations in the bedrooms of 74 participants aged 18 to 60.
There were nights without extra noise and nights in which road traffic noise was played over speakers 30 or 60 times for one minute and 15 seconds each.
The sound level was 41 to 44 decibels, equivalent to a quiet conversation. Participants did not know in advance whether, and to what sound levels, they would be exposed on a given night.
The next morning, cardiovascular values were measured, and blood samples were tested for inflammatory proteins. Ultrasound was also used to examine how much the blood vessels expand and contract with each heartbeat.
In general, functional and biological changes were evident after only one night with traffic noise, according to the study, led by Thomas Munzel at University Medical Centre Mainz in Germany.
These included elevated heart rates, changes in proteins and reduced vascular elasticity. The latter is considered an early warning sign for vascular health.
Research has long pointed to the negative health impact of environmental noise, which the World Health Organization describes as “one of the leading environmental risks for physical and mental health and well-being”.
In Germany, where the research was carried out, some 2.3 million people (or around 2.7 per cent of the population) are exposed to levels above 65 decibels during the day, and 2.6 million (3 per cent of the population) to levels above 55 decibels at night.
In light of the findings, the authors argued for consistent noise protection. This could include creating 30km/h zones and green spaces as noise buffers.
“Noise protection is vascular protection,” Munzel said.
“Every decibel of reduction means less stress on vessels, less inflammation in the blood and, in the long term, fewer heart attacks and strokes.”
Christoph Maack of University Hospital Wurzburg in Germany said this was a well-conducted study on an important topic.
“The study shows that there are changes that are unfavourable,” said the doctor, who was not involved in the research.
“Whether that is enough to leave lasting damage is something this study cannot show.”
There could be habituation effects with noise, he added.
However, he noted that epidemiological studies indicate that noise can strain the cardiovascular system. In that respect, measures to reduce noise are certainly sensible.
What happens if I am exposed to loud sounds over a long period of time?
Our graphic below shows how loud everyday sounds can be.
Noise at or above 85 decibels is harmful to our hearing. Prolonged exposure to noise above 85 decibels, especially for more than eight hours, can result in permanent hearing loss. As the noise gets louder, the amount of time it takes to damage your ears becomes even shorter.
You are in a place that is too loud if ...
-
you have to shout so other people can hear you.
-
you cannot hear someone speaking to you from only one metre away.
-
sounds seem quiet or muffled after you leave a noisy area.
-
your ears hurt or you hear a ringing sound for a few days or weeks after being in a loud place.
To help protect your hearing and overall health from loud noise, the American Speech-Language-Hearing Association recommends choosing quieter household appliances, setting your devices to no more than half volume and wearing earmuffs or earplugs in noisy settings, as these can decrease the noise level by as much as 30 decibels.
