Feb. 19 (HealthDay News) -- A breath of filtered indoor air may help your health, according to researchers in Denmark.

Using high efficiency particle air (HEPA) filters for just two days significantly improved a key measure of cardiovascular health in healthy, nonsmoking elderly individuals, according to a study published in the second February issue of the American Journal of Respiratory and Critical Care Medicine.

"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," Dr. Steffen Loft, of the Institute of Public Health in Copenhagen, said in a prepared statement.

Abnormal function of the inner lining of small vessels is known to be a predictor of dangerous or possibly fatal cardiovascular events.

HEPA filtration removed about 60 percent of the ultrafine, fine and coarse air particles in homes, according to researchers, and was associated with an 8.1 percent improvement in individual microvascular function (MVF).

"This suggests that indoor air filtration represents a feasible means of reducing cardiovascular risk," he said.

The researchers measured ambient airborne particles in the homes of 21 nonsmoking couples, aged 60 to 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. The size distribution and number concentration of indoor air particles in each home were continuously monitored.

Each couple's individual MVF was assessed using a noninvasive finger sensor.

"We expected that removing air particles with the HEPA filters would result in improvement of MVF, but we were heartened and surprised by the extent it did, considering the modest levels of particles in the indoor air of the homes of the elderly," Loft said.

SOURCE: American Thoracic Society, news release, Feb. 15, 2008