HEPA filters reduce cardiovascular health risks associated with air pollution

Using inexpensive air filters may help reduce cardiovascular disease risk that results from exposure to air pollution, according to researchers from Canada, who studied healthy adultsliving in a small community in British Columbia where wood burning stoves are the main sources of pollution. The researchers 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 findings were published online ahead of the print edition of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.

"Our main objectives were to evaluate the potential for a simple intervention to improve indoor air quality and reduce pollution-related cardiovascular health risks and to better understand the mechanisms that contribute to air pollution-related cardiovascular health problems" said Ryan Allen, PhD, assistant professor, Simon Fraser University, Burnaby, British Columbia. "Specifically, we were interested in learning more about the effects of residential wood smoke on the endothelium, the cells that line the inside of blood vessels, and on systemic inflammation, which is related to cardiovascular disease risk."

Previous studies on the effects of air pollution on cardiovascular disease have been conducted primarily in urban areas and have focused largely on vehicle emissions,Dr. Allen noted. The results of those studies have indicatedpollution causes inflammation in the lungs and vessels and may also cause endothelial cells to function poorly, ultimately contributing to cardiovascular disease; however, few studies have been conducted in smaller communities or communities where woodsmoke is a main source of pollution, he added.

The researchers recruited 45 adults from 25 homes. Individuals from self-reported tobacco-smoking households were excluded from participating. 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.