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Imaging data from more than 3,500 people showed that those living in areas with higher than recommended aircraft noise levels had thicker heart muscles that were less efficient at pumping blood around the body than those living in areas with lower aircraft noise levels.
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.
The researchers found in separate analyses of people not exposed to aircraft noise, that these types of heart abnormalities could result in two to four-fold increased risks of a major cardiac event such as a heart attack, life-threatening heart rhythms, or stroke when compared to the risk of persons without any of these heart abnormalities.
Senior author Gaby Captur, consultant cardiologist at the Royal Free Hospital and associate professor at UCL, said: “Our study is observational so we cannot say with certainty that high levels of aircraft noise caused these differences in heart structure and function.
“However, our findings add to a growing body of evidence that aircraft noise can adversely affect heart health and our health more generally.
“Concerted efforts from government and industry are needed to reduce our exposure to aircraft noise and mitigate its impact on the health of millions of people who live close to airports or under flight paths.”
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 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.
It is already known that exposure to high levels of aircraft noise is linked to higher blood pressure and obesity. In the new study, both factors were found to account for a significant portion of the link between aircraft noise and differences in heart structure and function.
First author Dr Cristian Topriceanu, from the UCL Institute of Cardiovascular Science added: “Between a quarter and a half of the link we observed was attributed to a higher body mass index (BMI) among participants exposed to higher levels of aircraft noise, while between 9% and 36% of the link was attributed to these participants having higher blood pressure (this was among those exposed to day-time aircraft noise only).
“Other factors that could be triggered by the stress response to aircraft noise include impaired sleep, inflammation, and atherosclerosis, which is a build-up of fats, cholesterol and other substances in our arteries.”
For the new study, published in the Journal of the American College of Cardiology, researchers looked at data from the UK Biobank of 3,635 participants who had had detailed magnetic resonance imaging (MRI) of the heart and who lived near Heathrow, Gatwick, Birmingham or Manchester airports.
They used UK Civil Aviation Authority estimates of aircraft noise level for every 100 square metres within those areas. Higher aircraft noise was defined as over 50 decibels on average during the day and 45 decibels on average during the night (11pm-7am). This is louder than the aircraft noise limits of 45 decibels during the day and 40 decibels at night recommended by the World Health Organization.
Among the UK Biobank participants in these areas, 8% lived in an area with high day-time aircraft noise, with 3% in an area with high night-time noise.
Comparing the hearts of individuals in higher and lower aircraft noise areas, the researchers took into account a wide variety of factors that might have skewed the results, including age, sex, BMI, socioeconomic status, lifestyle factors such as whether participants smoked and exercised, as well as participants’ exposure to road and rail noise and air pollution.
Heart MRIs were done at least three years after the estimates of aircraft noise in the participants’ neighbourhoods.
Participants who stayed in a higher aircraft noise area, the researchers found, had about 10-20% worse heart structure and function than their counterparts in these areas who moved away.
The research team then looked at a separate sample of 21,360 people who had detailed MRI scans of the heart as part of the UK Biobank study 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.
The study received funding from the Medical Research Council, British Cardiovascular Society, British Heart Foundation, a UCL Charlotte and Yule Bogue Research Fellowship, and the National Institute for Health and Care Research (NIHR).
Image: Gaby Captur
