Traffic noise found to increase hypertension risk

If you live near a busy road, it may feel like the constant sound of roaring engines, honking horns and wailing sirens makes your blood pressure rise. Now, a new study from UK and Chinese researchers has confirmed that this is closer to the truth than you might think.

Previous studies have shown a connection between noisy road traffic and increased risk of hypertension. However, strong evidence was lacking, and it was unclear whether noise or air pollution played a bigger role. The new research, published in JACC: Advances, shows that it is exposure to road traffic noise itself that can elevate hypertension risk.

“We were a little surprised that the association between road traffic noise and hypertension was robust even after adjustment for air pollution,” said lead author Jing Huang, an assistant professor at Peking University.

Previous studies of the issue were cross-sectional, meaning they showed that traffic noise and hypertension were linked, but failed to show a causal relationship. For the new paper, researchers conducted a prospective study using UK Biobank data that looked at health outcomes over time.

Researchers analysed data from more than 240,000 people (aged 40 to 69 years) who started out without hypertension. They estimated road traffic noise based on residential address and the common noise assessment method, a European modelling tool.

Using follow-up data over a median 8.1 years, they looked at how many people developed hypertension. Not only did they find that people living near road traffic noise were more likely to develop hypertension, they also found that risk increased in tandem with the noise ‘dose’.

These associations held true even when researchers adjusted for exposure to fine particles and nitrogen dioxide. However, people who had high exposure to both traffic noise and air pollution had the highest hypertension risk, showing that air pollution plays a role as well.

“Road traffic noise and traffic-related air pollution coexist around us,” Huang said. “It is essential to explore the independent effects of road traffic noise, rather than the total environment.”

The findings confirm that exposure to road traffic noise is harmful to our blood pressure, Huang said. Policymaking may alleviate the adverse impacts of road traffic noise as a societal effort, such as setting stricter noise guidelines and enforcement, improving road conditions and urban design, and investing advanced technology on quieter vehicles.

“To date, this is the first large-sized prospective study directly addressing the effect of road traffic noise on the incidence of newly diagnosed hypertension,” said Jiandong Zhang, author of an accompanying editorial comment, from The University of North Carolina at Chapel Hill. “The data demonstrated in this article 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.”

Huang said field studies are now underway to better understand the pathophysiological mechanisms through which road noise affects hypertension.

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