Washington, Jan 22 : Scientists have suggested that using inexpensive air filters may help reduce cardiovascular disease risk that results from exposure to air pollution.

Researchers from Canada, who studied healthy adults living in a small community in British Columbia where wood burning stoves are the main sources of pollution, found that high efficiency particle air (HEPA) filters reduced the amount of airborne particulate matter, resulting in improved blood vessel health and reductions in blood markers that are associated with an increased risk of cardiovascular disease.

The researchers recruited 45 adults from 25 homes. Each participant''s home was monitored for two consecutive seven-day periods, during which time a HEPA filter (Honeywell model 50300) was operated in the main activity room and a quieter HEPA filter (Honeywell 18150) was operated in the participant''s bedroom. HEPA filters were operated normally during one seven-day period and without the internal filters in place during the other period.

The order of filtration or non-filtration was random and participants did not know during which period the air was being filtered. Indoor pollution sampling equipment was placed in each home''s main activity room. Participants were asked to record their activities, locations and proximity to pollution sources every 60 minutes. Of the 25 homes enrolled in the study, 13 had woodstoves in use during the study period.

At the end of each 7-day period blood and urine samples were collected from each participant and markers of cellular injury, as well as the body''s response to that injury, were measured. Endothelial function also was evaluated using a fingertip device to evaluate blood volume in small blood vessels, and air samples were collected and analyzed.

After analyzing their data, the researchers found portable HEPA filters reduced the average concentrations of fine particulates inside homes by 60 pc and woodsmoke by 75 pc, and their use was associated with improved endothelial function (a 9.4 pc increase in reactive hyperemia index) and decreased inflammation (a 32.6 pc decrease in C-reactive protein).

"Our results support the hypothesis that systemic inflammation and impaired endothelial function, both predictors of cardiovascular morbidity, can be favorably influenced by a reduction of particle concentration and add to a growing body of evidence linking short-term exposure to particulate matter with a systemic inflammatory response," said Ryan Allen, assistant professor, Simon Fraser University, Burnaby, British Columbia.

The findings have been published online ahead of the print edition of the American Thoracic Society''s American Journal of Respiratory and Critical Care Medicine.