Exposure to aircraft noise linked to poor heart function
People who live close to airports and are exposed to high aircraft noise levels could be at greater risk of poor heart function, increasing the likelihood of heart attacks, life-threatening heart rhythms and strokes, according to a new study led by the University of College London (UCL).
As well as affecting sleep, noise from our environment can trigger stress responses and lead to an over-activation of the sympathetic nervous system (the network of nerves that controls our ‘fight or flight’ response), causing blood pressure to rise, arteries to constrict or dilate, and slower digestion. It can also cause the release of cortisol, the stress hormone, which can increase the appetite and cause weight gain. Aircraft noise may be more annoying than road or rail noise because of louder but intermittent noisy events and the unpredictability of the sound, which makes it difficult to get used to.
The new study, published in the Journal of the American College of Cardiology, looked at detailed MRI scans of the hearts of 3635 UK Biobank participants who lived close to four major airports in England: Heathrow, Gatwick, Birmingham and Manchester. The researchers used UK Civil Aviation Authority estimates of aircraft noise level within those areas; higher aircraft noise was defined as over 50 decibels on average during the day and 45 decibels during the night, which is in both instances five decibels higher than the limits recommended by the World Health Organization.
The team found that those who lived in areas with higher than recommended aircraft noise levels had stiffer and thicker heart muscles that contracted and expanded less easily and were less efficient at pumping blood around the body; this was especially the case for people exposed to higher aircraft noise at night, potentially due to factors such as impaired sleep and the fact that people are more likely to be at home at night and therefore exposed to the noise. Participants who stayed in a higher aircraft noise area had about 10–20% worse heart structure and function than their counterparts in these areas who moved away.
“We are concerned that the type of abnormalities we saw with night-time aircraft noise might result in increased risk of heart problems and stroke,” noted study co-author Professor Anna Hansell, from the University of Leicester. “Aircraft noise at night has been shown to affect sleep quality and this may be an important factor affecting health.”
The research team then looked at a separate sample of 21,360 UK Biobank participants to investigate how heart abnormalities comparable to those linked to higher aircraft noise might affect the risk of a major adverse cardiac event. They concluded that a hypothetical individual with these heart abnormalities may have up to four times the risk of an event such as a heart attack, abnormal heart rhythm or stroke.
It is already known that exposure to high levels of aircraft noise is linked to higher blood pressure and obesity. In this study, both factors were found to account for a significant portion of the link between aircraft noise and differences in heart structure and function.
“Between a quarter and half of the link was attributed to a higher BMI (body mass index) among participants exposed to higher levels of aircraft noise, while between 9% to 36% of the link was attributed to these participants having higher blood pressure (this was among those exposed to daytime aircraft noise only),” said first author Dr Cristian Topriceanu, from UCL.
“Other factors that could be triggered by the stress response to aircraft noise include impaired sleep, inflammation and atherosclerosis (build-up of fats, cholesterol and other substances in our arteries).”
Professor James Leiper, Associate Medical Director at the British Heart Foundation, concluded, “While observational studies like this can’t prove cause and effect, these findings add to previous research showing the damaging impact of noise pollution on our heart health. Further research will be needed to investigate the longer-term effects of aircraft noise on the health of those with the highest exposure.”
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