- In a randomized trial, using HEPA filters in the home reduced elevated blood pressure for those exposed to air pollution from living near major highways.
- Air filtration had no impact on such individuals who had normal systolic blood pressure (120 mm Hg or less).
- The researchers suggested targeting HEPA filtration use to vulnerable persons living near high-pollution roadways, including those with elevated blood pressure.
Use of HEPA filters reduced elevated blood pressure in people exposed to air pollution while living near major highways, a randomized trial showed.
Those living within 200 m (1/8 mi) of a high-traffic-volume highway had only a nonsignificant 0.5-mm Hg lower systolic blood pressure (SBP) while randomized to active HEPA filtration at home compared with sham filtration, reported researchers led by Douglas Brugge, PhD, MS, of the University of Connecticut in Farmington.
But baseline SBP moderated the impact of intervention (P=0.03), the group reported in Journal of the American College of Cardiology.
Among persons with an elevated brachial SBP of at least 120 mm Hg initially, HEPA filtration cut brachial SBP by 2.8 mm Hg (P=0.03) compared with a 0.2-mm Hg mean increase in SBP during the sham condition, for a net 3.0-mm Hg advantage over sham (P=0.04). Those with initially normal SBP saw no significant benefit on blood pressure.
"High blood pressure remains one of the most important modifiable risk factors for cardiovascular disease," Brugge said in a press release. "This research adds to growing evidence that simple interventions, like in-home air filtration, may help improve heart health for people at risk."
His group highlighted the "growing literature that indicates that air purifiers have a clinically important beneficial effect" on blood pressure even in a country with relatively low concentrations of fine particulate matter (PM <2.5 μmol/L in diameter) compared to many places globally.
"We believe it is a reasonable conclusion, given the lack of adverse effects, to recommend air purifier use for vulnerable populations, those with preexisting risk of cardiovascular disease such as elevated [blood pressure], and those who live within 200 m of high traffic highways or 100 m of high-traffic roads," they concluded.
The 3-mm Hg blood pressure reduction might seem modest but "aligns with other lifestyle interventions, and is associated with meaningful reductions in [cardiovascular disease] morbidity and mortality at the population level," Jonathan D. Newman, MD, MPH, of NYU Grossman School of Medicine in New York City, and colleagues wrote in an accompanying editorial.
U.S. annual air quality standards currently are <9 μg/m3 for PM2.5, although national regulation of clean air and environmental protection is currently "under existential threat," the editorialists wrote.
The trial included 154 adults living near highways I-93 and Rt-38 in eastern Massachusetts. They were randomly assigned to receive 1 month of either HEPA or sham filtration, which used the same air purifiers with the filter removed. This was followed by a 1-month "washout" period with no filtration and then 1 month of the alternate treatment. Air purifiers with clean filters were placed in the bedroom and living room. Participants were encouraged, but not required, to keep doors and windows shut as much as possible.
HEPA filtration cut arithmetic mean PM2.5 concentrations over a 24-hour period by about half from the "already quite low" 5.2 μg/m3 in the indoor sham levels to 2.5 μg/m3.
Overwhelming evidence shows the harmful health effects of PM2.5 exposure, even at levels below current U.S. standards, Newman's group wrote, adding that healthcare professionals are obligated to educate the public and support policies that improve the health of all Americans.
On the other hand, the editorialists cautioned that it was an unexpectedly large impact for such a small PM2.5 reduction. Also, a greater impact in the subgroup with elevated baseline SBP was "biologically plausible" but not prespecified in the trial protocol, raising concerns for type 1 error. "Additionally, the number of participants with SBP <120 mm Hg (n=91) exceeded those with SBP ≥120 mm Hg (n=61), an imbalance that may further complicate interpretation," they added. "When subgroup sizes are unequal, particularly in post hoc analyses, the risk of spurious findings increases."
Other study limitations noted by the researchers included limited generalizability due to a predominantly white, higher-income participant pool, exclusion of people on blood pressure medications, and a lack of data during hotter summer months or at times of higher indoor pollution.
Disclosures
The study was supported by the National Institute of Environmental Health Sciences and the School of Medicine at the University of Connecticut. The air purifiers were custom adapted by the manufacturer, Austin Air, and sold at a discount based on bulk purchase.
The researchers disclosed no relevant relationships with industry.
Newman disclosed receiving funding from National Institutes of Health relevant to the study; co-authors disclosed no relevant conflicts of interest.
Primary Source
Journal of the American College of Cardiology
Source Reference: Brugge D, et al "Effect of HEPA filtration air purifiers on blood pressure: A pragmatic randomized crossover trial" JACC 2025; DOI: 10.1016/j.jacc.2025.06.037.
Secondary Source
Journal of the American College of Cardiology
Source Reference: Newman JD, et al "Breathing easier air filtration to improve indoor air quality as a cardiovascular intervention" JACC 2025; DOI: 10.1016/j.jacc.2025.06.038.
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