The researchers in Denmark concluded after a four-days study that the high efficiency particle air (HEPA) filters may reduce the cardiovascular risk.

“Reduction of particle exposure by filtration of recirculated air for only 48 hours improved the microvascular function (MVF) in healthy elderly citizens,” said Professor Steffen Loft, M.D., D.M.Sc., of the Institute of Public Health in Copenhagen. “This suggests that indoor air filtration represents a feasible means of reducing cardiovascular risk.”

The team, lead by Professor Steffen Loft, M.D., D.M.Sc., of the Institute of Public Health in Copenhagen, has studied 21 non-smoking couples aged 60-75 who lived close to heavily trafficked roads.

They measured MVF and ambient airborne particles before and after the couples have used the HEPA filters. Each couple used air purifiers for two 48-hour periods. Besides evaluating each individual’s MVF, several secondary endpoints were studied in blood and urine samples to assess possible mechanisms of action: markers of inflammation, hemostasis, and oxidative stress.

“Our main finding was a significant improvement in the function of small finger blood vessels after reduction of indoor air particles. This effect most likely indicates a general improvement in the function of the inner lining of small vessels, including those supplying the heart,” said Dr. Loft.

The researchers found that HEPA filtration removed about 60 percent of the ultrafine, fine and coarse air particles in homes, and was associated with an 8.1 percent improvement in individual MVF.

None of the secondary endpoints considered showed significant differences after statistical corrections, suggesting that the mechanism underlying the improvement in MVF after air filtration remains unclear, and underscoring the need for further study.

“The results of this study indicate that reduction of particles in recirculated indoor air by filtration significantly improves MVF in a healthy, non-smoking, elderly population,” wrote Dr. Loft.