SEATTLE — Concerning new findings suggest the countless commuters who travel on high-traffic highways every day may be putting their cardiovascular health at risk. Scientists at the University of Washington report that unfiltered air from rush-hour traffic appeared to significantly increase passengers’ blood pressure — both while in the car and up to 24 hours later!
Sprawling, interconnected highways and roadways have been a common sight across virtually every urban area in the United States for decades upon decades, but scientists are only now beginning to fully grasp all of the health risks posed by the air pollution generated by all of those cars. Recent years have seen studies find that long-term exposure to traffic-related air pollution is linked to higher rates of heart disease, lung cancer, asthma, and death. What exactly is traffic-related air pollution? Researchers explain it as a complex mixture of exhaust from tailpipes, brake and tire wear, and road dust.
Now, this latest project indicates those health risks are also common in people habitually traveling on busy roads.
“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 physician and professor of environmental and occupational health sciences who led the study, in a media release.
An earlier experiment performed in Kaufman’s lab had already found that exposure to diesel exhaust fumes can increase blood pressure in a controlled environment. The roadway traffic study, meanwhile, was put together to test that finding in a real-world setting by isolating the effects of traffic-related air pollution.
Study authors drove a group of healthy participants (ages 22-45 years old) through rush-hour Seattle traffic while monitoring their blood pressure. During two of the trips, unfiltered road air was allowed to enter the car. This was done to mimic or recreate precisely how many people drive in real-life. During the third trip, the car was equipped with high-quality HEPA filters that blocked out 86 percent of particulate pollution. The entire time, participants were unaware whether they were on a clean air drive or a roadway air drive.
Consequently, breathing in unfiltered air resulted in net blood pressure increases among subjects of over 4.50 mm Hg (millimeters of mercury) in comparison to drives with cleaner, filtered air. This increase usually happened in a rapid manner, peaking about an hour into the drive and then subsequently remaining steady for the following 24 hours, at least. Study authors did not test past the 24-hour mark.
Incredibly, findings show the size of the observed increase is comparable to the effect of a high-sodium diet.
“We know that modest increases in blood pressure like this, on a population level, are associated with a significant increase in cardiovascular disease,” Prof. Kaufman explains. “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.”