Findings can support public health measures offering “higher quality of evidence” to justify the potential to modify road traffic noise and air pollution
Road traffic noise and air pollution are known to affect heart health, but previous studies couldn’t say whether noise or air pollution was the cause, and which played a greater role. Now, a new study in JACC: Advances confirms it’s the sound of busy road traffic that can elevate hypertension risk.
The study, the first in the UK to directly investigate the effects of long-term exposure to road traffic noise on hypertension occurrence, analysed UK Biobank data – which looks at health outcomes over time – from over 240,000 people aged 40 to 69 years without hypertension.
Using follow-up data over a median of 8.1 years, they found people living near road traffic noise were more likely to develop hypertension, and that risk increased with noise ‘dose’, associations which held after adjusting for fine particles and nitrogen dioxide exposure. However, people who had high exposure to both had the greatest hypertension risk, showing that air pollution also plays a role.
“Road traffic noise and traffic-related air pollution coexist around us,” said lead author, Jing Huang, Assistant Professor, from the Department of Occupational and Environmental Health Sciences at Peking University. “It is essential to explore the independent effects of road traffic noise, rather than the total environment.”
The study provides “a robust piece of evidence that there is a potential causal relationship between road traffic noise and hypertension, independent of air pollution and many other well-known risk factors,” said Samuel Y Cai, lecturer in environmental epidemiology at the University of Leicester's Centre for Environmental Health and Sustainability. "This is a game-changer when it comes to the prevention of hypertension at individual and societal levels."
Previous studies linking noise and pollution and heart health were of insufficient quality to affect policy, but these findings can support public health measures because they confirm that exposure to road traffic noise is harmful to our blood pressure, said Huang: “The data… provides a higher quality of evidence to justify the potential to modify road traffic noise and air pollution from both individual and societal levels in improving cardiovascular health.”
“Traffic noise and air pollution from UK roads have serious effects on the health of our circulation, confirming research in other parts of the world,”
Dr Mark Miller, Senior Research Scientist, British Heart Foundation (BHF) described the study as an “impressive piece of work”.
“Traffic noise and air pollution from UK roads have serious effects on the health of our circulation, confirming research in other parts of the world,” he said. “The effects on blood pressure were clearly worse with the combination of noise and air pollution, despite the air pollution levels being at UK government guidelines. The message, once again, is that we need to be reducing our reliance on vehicles and planning our cities to minimise our exposure to noise and air pollution.”
Field studies are underway to better understand the pathophysiological mechanisms through which road noise affects hypertension, but “this should not delay actions to recognise that traffic noise is a potential risk factor for hypertension, and heart diseases more generally," said Cai.
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