Loud Road Noise Linked to Increased Risk of High Blood Pressure
Wailing sirens, aggressive horns, the roaring engines of giant diesel trucks — most of us would agree road noise is super annoying, but is it actually harmful to your health? A new study published on March 22 in the journal JACC: Advances found that busy road noise was linked to an increased risk of having high blood pressure, a top risk factor for heart attack and stroke.
Previous studies have found a connection between loud road noise and hypertension, but because noise pollution often comes with air pollution, the impact of noise alone was unclear. This new study was able to control for the health effects of air pollution and the risk for hypertension remained, according to the authors.
“We are a little bit surprised that the association between road traffic noise and hypertension was robust even after adjustment for air pollution,” says lead author Jing Huang, PhD, assistant professor in the department of occupational and environmental health sciences in the School of Public Health at Peking University in Beijing, China.
That being said, the 2021 European Society of Cardiology Guidelines on cardiovascular disease prevention has already highlighted that environmental exposures, including above-threshold noise levels, as having the potential to increase heart disease risk, says Dr. Huang.
Nearly Half of U.S. Adults Have High Blood Pressure
Blood pressure is simply a measurement of the pressure of blood pushing against the walls of the arteries. If blood pressure stays high for a long time, it can cause damage to organs, including your heart, brain, kidneys, and eyes.
Nearly half of adults in the United States — 47 percent, or 116 million people — have hypertension, according to the Centers for Disease Control and Prevention. Hypertension is defined as having a systolic blood pressure greater than 130 millimeters of mercury (mmHg) or a diastolic blood pressure greater than 80 mmHg. If you’re taking medication for hypertension, even if your blood pressure improves, you’d still have a hypertension diagnosis.
The Louder the Road Noise, the Greater the Risk for Hypertension
To carry out this prospective study, researchers analyzed UK Biobank data from nearly 250,000 people, ages 40 to 69, who started the study without hypertension.
Investigators estimated road traffic noise based on residential address and the Common Noise Assessment Method, a modeling tool developed by the European Commission.
After following participants for a median of 8.1 years, the investigators found that more than 21,000 developed high blood pressure. Researchers found that people living near road traffic noise were more likely to develop hypertension. They also found what’s called a “dose-dependent relationship” — the greater the amount of road noise, the greater the risk.
“This is an interesting study because it is looking into a relationship that we typically don’t think of when thinking about high blood pressure, which is the impact of noise level and air pollution on high blood pressure,” says Jim Liu, MD, a cardiologist at The Ohio State University in Columbus, who was not involved in this research.
“In theory, this relationship could make sense, since increased noise or pollution could increase stress on the body and cause elevations in blood pressure. Long-term noise stimulation could cause increased stress on the body,” he says.
Anything that triggers stress on the body could affect blood pressure by causing various physiologic changes, such as sympathetic nervous activation, increasing inflammation, or fluctuations in adrenal gland hormones, says Dr. Liu.
People Exposed to Both Air Pollution and Traffic Noise Had the Highest Hypertension Risk
These associations held true even when researchers adjusted for exposure to air pollutants, including fine particles and nitrogen dioxide. The participants who had high exposure to both traffic noise and air pollution had the highest risk for high blood pressure, showing that air pollution plays a role as well, according to the authors.
Air pollution caused nine million deaths worldwide in 2019, according to the Global Burden of Disease (GBD) study, published in The Lancet in 2020, and an estimated 3 out of 5 of those deaths were due to cardiovascular disease, including heart attack and stroke.
Particulate matter levels (a measure of the amount of tiny pieces of matter such as dust or smoke) are linked to the risk of heart disease, heart attack, and stroke, as well as cardiovascular risk factors, including hypertension and diabetes, according to a meta-analysis published in November 2021 in The New England Journal of Medicine.
Ewen Chao, MD, an otologist (or specialized ear doctor) at Stony Brook Medicine in New York, agrees that the findings are interesting and that the study, “does a good job of trying to isolate the effects of traffic noise from other factors. While the effect is small, this paper certainly is a strong addition to a growing literature of studies that supports the correlation of noise and its effects on the cardiovascular system.”
Many Variables That Estimate Noise Exposure Are Hard to Measure
There are some limitations to the study, which the authors acknowledge, says Dr. Chao. “It uses a model based on the individual's home address to estimate the noise pollution, which unfortunately cannot account for many variables such as how much time the person actually spends at the home address, and so it cannot precisely measure the true amount of noise exposure,” she says.
It's also worth noting that the noise level was only assessed at the beginning and not the rest of the eight-year follow up period, says Liu. “Also, the noise level measured was outdoor noise level and may not necessarily reflect indoor noise level,” he says.
These findings could be used to support public health measures because they confirm that exposure to road traffic noise is harmful to our blood pressure, according to the authors.
Further studies are still needed to continue exploring the underlying mechanisms in the body that could be behind the relationship between road traffic noise exposure and hypertension in the presence of air pollutants, says Huang.
How Can I Drown Out Road Traffic Noise?
Doing things to minimize noise traffic could help reduce the health effects of road noise, especially if the noise is severe enough and particularly bothersome to the individual, says Liu.
“Noise prevention is very doable, and can include moving away from the noise, turning down the volume of the noise, or blocking the noise, for example, by increasing noise insulation materials, or by wearing hearing protection,” says Chao.
Hearing protection can include earplugs or earmuffs, she says. “It is important to find a device that has a good fit in or on the ear. It is also important to look at the noise reduction rating (NRR) [defined at Custom Protect Ear] on a given piece of equipment. A higher NRR will block more sound,” she says.
Some electronically powered devices also offer active noise cancellation, says Chao. Sound waves travel through the air and into your ear canal, where they vibrate your eardrum. Active noise cancellation works by creating an opposing sound wave to negate sounds, she explains.
“Noise machines (noise masking) would be less likely to help, as it would only add to the overall volume of noise exposure,” says Chao.
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