New Study: If Your Commute Includes This, It Could Be Raising Your Blood Pressure

Updated: Mar. 21, 2024

Shockingly, it's not because of traffic-jam stress: A new study explores an often-overlooked risk factor your daily trek to work can cause.

Unless your home is your office, having a job typically comes with an often pesky requirement: The dreaded commute. If you don’t opt for public transportation or a bike commute, chances are that journey to and from work involves getting in a car. If that’s the case for you though, new research examining the effects of commuting on blood pressure may inspire you to map out a different route. Science had previously identified a connection between the two (that’s not news for anyone who’s sat in slow-moving traffic), but the specific link was unclear—until now.

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The National Institutes of Health (NIH) shares a troubling statistic: Around the world, air pollution is linked to more than 6.5 million deaths annually. This alarming figure has been rising for the last two decades, with human activities such as using heating fuels, vehicle emissions, industrial byproducts, and coal-powered electricity generation as primary culprits. In a bid to shed further light on this issue, a collaborative research effort between the University of Washington (UW), supported by both the US Environmental Protection Agency (EPA) and the NIH, explores the effects of air pollution encountered during daily commutes on blood pressure.

At the center of this issue is traffic-related air pollution (TRAP). Comprising a mix of harmful substances like ground-level ozone, nitrogen oxides, and fine particulate matter, TRAP is a byproduct of the congested roads we navigate daily. Prior studies have already identified TRAP as a key risk factor for cardiovascular diseases, including hypertension.

The study, published in November 2023 in the peer-reviewed journal Annals of Internal Medicine, suggests that exposure to unfiltered air during peak traffic can significantly elevate passengers’ blood pressure. “The body has a complex set of systems to try to keep blood pressure to your brain the same all the time,” explains lead study author Joel Kaufman, MD, MPH, a UW physician and professor of environmental and occupational health sciences. He adds in a press release, “It’s a very complex, tightly regulated system, and it appears that somewhere, in one of those mechanisms, [TRAP] interferes with blood pressure.”

The research involved healthy participants aged 22 to 45 driving through Seattle’s rush-hour traffic. The unique approach was the environmental control: Participants were exposed to typical unfiltered road air on two occasions, while on a third drive, a car equipped with high-quality HEPA filters provided cleaner air. Surprisingly, participants’ blood pressure spiked by over 4.50 millimeters of mercury (mmHg) in the unfiltered air compared to the HEPA-filtered environment—this increase was not only rapid, peaking about an hour into the drive, but it also persisted for at least 24 hours. According to experts, the magnitude of this increase is notably similar to the effects of a high-sodium diet.

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The impact of ultrafine particles

The study also highlights a concerning aspect of air pollution: Ultrafine particles. These tiny culprits, less than 100 nanometers in diameter and invisible to the naked eye, are abundant in TRAP and are a growing concern for public health. These particles can penetrate the respiratory system and possibly the bloodstream, bearing toxic substances. Dr. Kaufman remarks, “Ultrafine particles are the pollutant that were most effectively filtered in our experiment—in other words, where the levels are most dramatically high on the road and low in the filtered environment. So, the hint is that ultrafines may be especially important [for blood pressure].” This statement points to the possible substantial impact of ultrafine particles, emphasizing the need for more detailed research to explore their precise effects on public health.

While the link between TRAP and blood pressure is a critical piece of the puzzle, it also opens doors for potential solutions. Perhaps it’s time to consider HEPA filters in our vehicles or rethink our commuting habits. What’s clear is that every step toward cleaner air is a step toward better heart health.

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