Even 1 night of hearing traffic noises can harm heart

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, reported dpa.

For a study published in the journal Cardiovascular Research in late February, researchers in Germany simulated different situations in the bedrooms of 74 participants aged 18 to 60.

There were nights without additional noise and nights in which road traffic noise was played over speakers 30 or 60 times for 1 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. Alcohol, caffeine and nicotine were off limits during the study.

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.

One finding was that volunteers reacted with differing sensitivity to noise. In general, functional and biological changes were evident after only one night with traffic noise, according to the study, led by Thomas Münzel 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, they said.

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% of the population) are exposed to levels above 65 decibels during the day, and 2.6 million (3% 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 30 km/h zones and green spaces as noise buffers.

"Noise protection is vascular protection," said study leader Münzel. "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 Würzburg in Germany called it a well-conducted study on an important topic. "The study shows that there are changes that are unfavourable," said the physician, who was not involved in the research.

"Whether that is enough to leave lasting damage is something this study cannot show." There may be habituation effects with noise, he said.

However, he noted that epidemiological studies indicate that noise can strain the cardiovascular system. In that respect, measures to reduce noise are certainly sensible.