Living near high-traffic roads can expose people to tiny particles of air pollution believed to raise blood pressure, but a new study suggests a simple fix: using a high-efficiency particulate air—or HEPA—purifier.
HEPA filters are often considered the most effective air purifiers and are designed to remove up to 99.97% of small (as minuscule as 0.3 microns) airborne particle pollutants, including exhaust from vehicles and matter released from tire wear.
In the study, people who lived near a busy highway and had elevated blood pressure saw a drop in their readings when using a HEPA filter—but not when using a non-HEPA one, researchers reported in the Journal of the American College of Cardiology on August 6.
High blood pressure is a major risk for heart disease and increases the chances of developing a heart attack, stroke, or heart failure. Research has found that even small changes in blood pressure are linked with a reduction in adverse cardiovascular events.
As such, the new paper has “major public health implications,” JoAnn E. Manson, MD, DrPH, chief of the division of preventive medicine at Brigham and Women’s Hospital, who wasn’t involved in the study, told Health.
The research aimed to address concerns from community members—first raised about 20 years ago—about pollution from highways in the Boston area, Doug Brugge, PhD, an author of the new study and a professor at the University of Connecticut, told Health.
For the study, Brugge and his colleagues recruited 154 people living within 200 meters of at least one high-traffic highway in eastern Massachusetts. The average participant age was 41, the majority—68%—were white, and most were of higher socioeconomic status.
The study used a randomized crossover design, in which each participant tried both interventions—in this case, using air purifiers with and without HEPA filters. This approach helps reduce the impact of individual differences, so researchers can be more confident that any changes were due to the purifier itself.
Participants used an air purifier fitted with either a HEPA or non-HEPA filter for a month each, with a month-long washout period in between when no air purifier was used.
Blood pressure was measured at the start of the study and after each month. At baseline, about 40% of participants had elevated systolic blood pressure (120 mm Hg or higher), the top number in a blood pressure reading.
On average, systolic blood pressure for people with higher readings at baseline dropped by 2.8 mm Hg after one month of HEPA filtration, which also halved PM2.5 levels in the participants’ homes.
In contrast, systolic blood pressure increased by 0.2 mm after a month using a non-HEPA purifier. There was no significant difference in blood pressure after using the air filters for people with normal blood pressure levels.
The finding that HEPA filtration is associated with reduced blood pressure aligns with previous studies examining the connection, Christopher Carlsten, MD, MPH, a professor at the University of British Columbia who wasn’t involved in the study, told Health.
However, the authors of this new study—which Manson called “rigorous”—note that their trial was larger than earlier ones and didn’t restrict participants’ daily activities, unlike many others.
The results suggest that using a HEPA air purifier could offset a rise in blood pressure associated with living near vehicle-congested roads—a reality for about 24% of Americans, researchers have found.
But it’s important to remember that the findings may not apply to the broader public because the paper focused on “a fairly specific study population,” Brugge noted. Most participants were white and well off, and they didn’t have serious cardiovascular conditions or take blood pressure medication.
Furthermore, there hasn’t been much research into the effectiveness of HEPA filters for cardiovascular concerns, Rachel Goodman, MD, chief cardiology fellow at Tufts Medical Center who wasn’t involved in the study, told Health. Using them isn’t part of official heart-healthy guidelines, she noted.
Still, “air purifiers have a lot of benefit and no obvious downside other than the cost,” said Brugge, noting that he uses HEPA filters in his own home. The devices can also remove mold, dust, and pollutants from wildfires, and help reduce the spread of airborne pathogens like SARS-CoV-2 and the flu.
Brugge suggests looking for a HEPA purifier that doesn’t generate ozone or ionize the air, because those may be ineffective and could release more pollutants. It’s also important to check the specifications to ensure the purifier provides enough filtration for the room.
People at risk may stand to gain the most. “An indoor air purifier can empower individuals to protect themselves if they live near high-traffic roadways, which may be of greatest benefit if they already have elevated blood pressure or other risk factors for cardiovascular disease,” said Manson.
