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Breathing in highway air pollution raises your blood pressure, study shows

woman in car driving on highway - highway air pollution
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Not only can driving on a highway increase your blood pressure—so can breathing polluted air from all the traffic.

A study in the Annals of Internal Medicine found that inhaling unfiltered air from highways significantly increased passengers’ blood pressure. Get this: The road pollution can affect you while you’re in the car and up to 24 hours later.

(Sounds like now’s a good time to get a new cabin air filter, right?)

We know that long-term exposure to traffic-related air pollution is associated with higher rates of asthma, cardiovascular disease, lung cancer and death.

But new research from the University of Washington found that being exposed to diesel exhaust fumes raised blood pressure while people were driving—and even after they reached their destination.

“The body has a complex set of systems to try to keep blood pressure to your brain the same all the time. It’s a very complex, tightly regulated system, and it appears that somewhere, in one of those mechanisms, traffic-related air pollution interferes with blood pressure,” says Joel Kaufman, a UW doctor and professor of environmental and occupational health sciences, who led the study.

Dr. Kaufman’s team drove healthy participants between the ages of 22 and 45 through rush-hour traffic in Seattle and monitored their blood pressure at the same time.

The researchers let unfiltered road air into the car on two of the drives. On the third trip, the car included a high-quality HEPA filter. That did the job to prevent 86% of particulate pollution from getting into the vehicle. The participants didn’t know whether the car had an air filter in place or not.

Breathing unfiltered air resulted in net blood pressure increases of more than 4.50 mm Hg (millimeters of mercury) when compared to driving with filtered air.

The increase in blood pressure happened quickly, peaking about an hour into the drive. In some cases, the increase persisted for at least 24 hours. The researchers didn’t explore the blood pressure ranges past the 24-hour mark.

“We know that modest increases in blood pressure like this, on a population level, are associated with a significant increase in cardiovascular disease,” Dr. Kaufman says.

“There is a growing understanding that air pollution contributes to heart problems. The idea that roadway air pollution at relatively low levels can affect blood pressure this much is an important piece of the puzzle we’re trying to solve,” Dr. Kaufman adds.