Using HEPA filters for just two days significantly improved a key measure of cardiovascular health in healthy, non-smoking elderly individuals, revealed by researchers in a recent study.
“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.”
Abnormal function of the inner lining of small vessels is known to be a predictor of dangerous or possibly fatal cardiovascular events.
The study was published in the second issue for February of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
A high efficiency particulate air or HEPA filter is a type of high-efficiency air filter. HEPA filters can remove at least 99.97% of airborne particles 0.3 micrometers (?m) in diameter. Particles of this size are the most difficult to filter and are thus considered the most penetrating particle size (MPPS). Particles that are larger or smaller are filtered with even higher efficiency. HEPA filters are composed of a mat of randomly arranged fibres. Key metrics affecting function are fibre density and diameter, and filter thickness. The air space between HEPA filter fibres is much greater than 0.3 ?m.
The researchers measured MVF and ambient airborne particles in the homes of 21 non-smoking couples aged 60-75 who lived close to heavily trafficked roads. Each couple used air purifiers for two 48-hour periods. During one period, the purifier was equipped with a HEPA filter, and during the other, it ran without it, so that each individual served as his or her own control. The size distribution and number concentration of indoor air particles in each home were continuously monitored.
The researchers then assessed each individual’s MVF using a noninvasive finger sensor. 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.
“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. “The improvement could not be ascribed to significant reduction in inflammation or oxidative stress by means of biomarkers.”