doi:  10.1289/ehp.119-a164aINDOOR AIR QUALITY: Wood-Burning Stoves Get Help from HEPA FiltersAuthor information Copyright and License information In many regions wood is seen as a cheap, renewable resource, and burning wood to heat homes is prevalent in rural and urban areas of North America and Europe. A small, preliminary study suggests air purifiers equipped with high-efficiency particle air (HEPA) filters can lower the amount of indoor fine particulate matter (PM2.5) and smoke from woodstoves, potentially reducing residents’ risk of cardiovascular disease from exposure to these air pollutants. “Our study is the first that I’m aware of that has shown any measurable health benefit from HEPA filtration in wood-burning communities in relatively young, healthy people,” says study leader Ryan Allen, an assistant professor of health sciences at Simon Fraser University, Burnaby, British Columbia.The researchers monitored 45 nonsmoking adults, average age 43 years, living in 25 homes in Smithers, British Columbia

, where residential wood burning is common. Air purifiers costing about $150 were placed in the most active room of the house and the bedroom. The air purifiers ran for 7 days with the HEPA filter inserted and another 7 days without. The order of filter and control conditions was randomly selected for each participant, and participants were unaware of filter status.Levels of PM2.5 and levoglucosan, a validated tracer of woodsmoke, were measured inside and outside the homes. At the end of each 7-day period, blood and urine samples were assessed for markers of inflammation and oxidative stress, and microvascular endothelial function was measured by peripheral artery tonometry.Use of the HEPA filters reduced indoor PM2.5 concentrations by 60%, and indoor levoglucosan levels fell by 75% on average, compared with nonuse. HEPA filtration was linked to a 9.4% increase in the reactive hyperemia index (RHI), a marker of endothelial function, and a 32.6% decrease in C-reactive protein, a marker of inflammation.

A reduced RHI reflects an impaired blood vessel response to changes in blood flow and is an early indicator of atherosclerosis. These physical changes occurred even though PM2.5 levels were relatively low to begin with—about 11 μg/m outdoors compared to the U.S. Environmental Protection Agency’s annual average standard of 15 μg/m.4Even people who don’t use woodstoves themselves may benefit from HEPA filters, Allen says. air purifier australia“Most stoves don’t put smoke into your living room directly,” he explains; best air purifier for odors reviewsinstead, smoke that is vented outdoors leaks back into nearby homes through cracks around doors and windows.clean air and water act 1972A larger, better-controlled study is needed to confirm these findings, as well as determine any long-term health benefits of filtering indoor air, such as preventing strokes or heart attacks.

Still, these initial results are promising in a world where indoor air pollution from solid fuels such as wood is a top global risk factor for disease and premature death. Moreover, says Lars Barregard, a professor of occupational and environmental medicine at the University of Gothenburg, Sweden, “The use of wood for heating may become more common as the cost of other fuels rise or fossil fuels are restricted.”Naeher LP, et al. Woodsmoke health effects: a review. 2. Allen RW, et al. An air filter intervention study of endothelial function among healthy adults in a woodsmoke-impacted community. [online 21 Jan 2011] 3. Deanfield JE, et al. Endothelial function and dysfunction: testing and clinical relevance. 2.5 Washington, DC: U.S. Environmental Protection Agency; [[accessed 14 Mar 2011]]. Fine Particle (PM2.5) Designations. (updated 6 Aug 2010). Prüss-Ustün, et al. Knowns and unknowns on burden of disease due to chemicals: a systematic review. Best Air Purifier to Use With a Woodstove

Burning wood for heat can save money on energy bills. Soot and other particles related to burning wood in the home however, can cause symptoms associated with breathing disorders such as asthma, allergies and emphysema. Fine particles of soot increase the amount of dust in the home. Using an air purifier can help reduce dust and allergic response to the fine particles created with burning wood for heat. The size of soot and ash from burning wood can range from .2 to 3 microns or larger. Air purifiers and filtration units are rated according to their Minimum Efficiency Reporting Value (MERV) rating. The MERV rating ranges from 1 to 20 with 1 providing the least amount of filtration. According to the Environmental Protection Agency (EPA) and the MERV rating chart, filters with a MERV rating of 17 to 20 have the ability to filter particles as small as .3 microns when new and smaller particles as the filter has been in operation longer. The currently available type that filters particles this small out of the air is a High Efficiency Particulate Air (HEPA) filter.

The particles captured create smaller air passages so even smaller particles are captured as the filter is used. The best air purifier to use with a wood stove to capture soot, ash and other combustion-related particles is a unit that uses HEPA filters for air purification. Install air purifiers as a whole-house system, large room-size units and table-top units for lighter filtration needs. The best type of unit to use with a wood stove will depend on the budget allowed for air purification. Whole-house systems are very expensive, but they will effectively remove most of the particles associated with burning a wood stove. The best type of unit to use for an average budget is a room-size air purification unit placed in the room with the wood stove. A table-top unit has limited air flow and may not make a noticeable difference in the amount of particles associated with burning a wood stove in the air--especially for those with respiratory disorders who are sensitive to airborne particles.