Thanks to Pollution, Being Stuck in Traffic Can Raise Your Blood Pressure

City skyline seen covered in smog.
Alexander Spatari/Getty Images
  • Air pollution could affect your blood pressure, even when you’re in your vehicle.
  • Particulate matter, which can be invisible to the naked eye is easily absorbed through the lungs.
  • Experts warn that particulate matter in air pollution contributes to millions of deaths annually.

If you needed another reason to hate your morning commute, here’s more bad news: traffic pollution could have a negative impact on your blood pressure.

Research suggests that air pollution isn’t just some vague threat to the environment and your health, but has quantifiable effects similar to smoking or salt, that can lead to long-term, chronic effects on the heart and lungs.

In a new scientific paper published in Annals of Internal Medicine, researchers found that exposure to “traffic-related air pollution,” which includes gasses like carbon dioxide, and particulate matter from brakes and tires, can raise your blood pressure. And those effects persisted for a full day after the exposure.

The research also finds ultrafine particulate matter, a form of pollution associated with car traffic that is currently unregulated, as a growing concern among public health officials.

“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,” Dr. Joel D. Kaufman, a Professor of Epidemiology at University of Washington, and author of the research, told Healthline.

Research in Rush Hour

Kaufman and his team wanted to understand how traffic-related pollution could affect drivers’ blood pressure during their commute. So, they created a novel study concept in which they would literally drive around participants in morning rush hour in Seattle. On some of the drives, their vehicle would be equipped with a standard car air filter and a high-efficiency particulate air (HEPA) filter. On other drives, all filtration was removed from the vehicle, with outside air vented directly into the cabin.

Sixteen participants were recruited for the experiment, although full research data was only completed for thirteen. Participants were between 22-45 years of age with an average age of 30. Everyone was generally heart healthy: individuals were disqualified if they had high cholesterol, hypertension, diabetes, and cardiovascular disease. 

Participants underwent three separate drives for the experiment. Two drives were “unfiltered,” while the third drive was “filtered.” Each drive was separated by three weeks and the study was double-blind, meaning neither the participants nor the driver were aware of the vehicle having air filtration or not.

Each drive consisted of a two-hour commute through rush hour traffic, generally between 9:30-11:30 AM. 

Prior to each drive and at various points during the experiment, researchers took blood pressure readings for the participants. 

How pollution affects blood pressure

Effects of pollution peaked one hour into the drive and on average raised diastolic blood pressure by 4.7 mm/Hg and systolic blood pressure by 4.5 mm/Hg. While diminished, the effects lasted for an additional day. After 24 hours, diastolic blood pressure was still 3.8 mm/Hg higher than baseline, while systolic was still elevated by 1.1 mm/Hg.

“The findings add more evidence in support of the experimental science showing that exposure to traffic-related air pollution particles increases the risk for cardiovascular diseases,” said Dr. Robert D. Brook, a Professor of Medicine in the Division of Cardiovascular Diseases at Wayne State University.

Brook wasn’t affiliated with the research, but has previously published on the effects of air pollution on the cardiovascular system.

In a 2020 paper entitled “Inhaling Hypertension,” Brook and his co-author found that fine particulate pollution contributes to 8.9 million deaths per year worldwide. 

“Reducing exposure to traffic — one of the most common sources of particulate air pollution encountered every day by billions of people worldwide — can play a key role in protecting the global population from the harmful cardiovascular health effects,” he told Healthline.

What is particulate matter?

What is in exhaust — and how do you regulate it?

Traffic-related pollution isn’t any one thing; in fact it is a lot of different things, in different sizes. There are numerous gas emissions, including carbon dioxide, carbon monoxide, and nitrogen dioxide. Then there is particulate matter, which varies by size. PM10 particles are 10 micrometers or smaller, while PM2.5, classified as “fine” particulate matter, are 2.5 micrometers or smaller. Finally, PM0.1, or “ultra fine” particles, are less than one tenth of a micrometer.

To put that in perspective, the diameter of a single strand of human hair is about 70 micrometers.

Ultrafine particulate matter generally enters the body through the lungs, and is associated with systemic inflammation and increased risk of cardiovascular disease and hypertension, among other health effects.

Kaufman’s research further indicates that fine and ultrafine particulate matter can affect the body’s cardiovascular system and blood pressure.

“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,” said Kaufman.

Dr. Panagis Galiatsatos, a pulmonary and critical care physician at Johns Hopkins University, and spokesperson for the American Lung Association, told Healthline that, like smoking, air pollution is a public health fight that can be won.

“Find the right advocacy outlets in order to promote better, safer, cleaner air. The lung association is one of those organizations. You deserve that air quality. And I think this is a very winnable battle,” he said.

“Economically and politically, there are ways to promote safer, cleaner cars,” said Galiatsatos.

The bottom line

Pollution from vehicle traffic can affect your blood pressure and cardiovascular health.

New research indicates that exposure to traffic-related pollution can elevate your blood pressure, and keep it elevated for 24 hours.

Air pollution can lead to long-term chronic health problems. Experts warn that it is a serious global health concern.

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