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Most of us are familiar with road rage — aggressive driving that’s caused by stress or anger behind the wheel. But the honking of horns and revving of engines doesn’t just affect those in the vehicle — it can also raise the blood pressure of people living near the road.
Previous research had shown a connection between road traffic noise and an increased risk of hypertension — high blood pressure — but it was still unclear whether it was the noise or the pollution from the traffic that was the cause. Now, researchers say they have the evidence for it.
Using health outcome data from biomedical database UK Biobank, which contains genetic and health information from half a million UK participants, researchers analyzed data from more than 240,000 40- to 69-year-olds who did not initially have hypertension.
The team from the American College of Cardiology used residential addresses and a European modeling tool, the Common Noise Assessment Method, and looked at follow-up data over a median of 8.1 years to see how many people developed high blood pressure.
The results, published Wednesday in the journal JACC: Advances, surprised researchers. People living near road traffic noise were not only more likely to develop high blood pressure, but the risk of this outcome increased with the “dose” of noise, even when researchers adjusted for fine particles and nitrogen dioxide.
Senior author Kazem Rahimi, professor of cardiovascular medicine and population health at the University of Oxford, told CNN: “Because areas that are noisy tend to have a high level of air pollution as well, one question that arises is whether each are independently contributing to risk and this was indeed the case. Living in noisy and polluted zones amplified the risk of hypertension.”
That’s not to say air pollution doesn’t play a role in hypertension: Those who had a high exposure to road traffic noise and air pollution had the highest hypertension risk.
“We did not detect a threshold of noise above which the risk started to increase. The risk increased with higher levels of noise, starting at the lowest category that was measured in the study,” Rahimi said, adding that this was 10 decibels.
“The association was graded: That means the higher the noise level the higher risk of hypertension in the future,” Rahimi told CNN in an email.
Rahimi added: “Policymaking towards road traffic noise control as a societal effort would be helpful, such as setting stricter noise guideline and enforcement, improving road conditions and urban design, and investing advanced technology on quieter vehicles such as EVs (electric vehicles).”
Some 1.28 billion adults aged 30-79 years worldwide have hypertension, with two-thirds living in low- and middle-income countries, according to the World Health Organization (WHO).
The condition increases the risk of heart disease and stroke, which are two leading causes of death for Americans, according to the Centers for Disease Control and Prevention. But an estimated 46% of adults are unaware that they have hypertension, according to WHO.
Older age, genetics, being overweight or obese, not being physically active, high-salt diet and drinking too much alcohol increase the risk of having high blood pressure, WHO says.
As the condition usually has no symptoms, the best way to find out if you have it is to have your blood pressure measured, so you can manage it and reduce your risk.