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Indoor wood, candle burning may create potentially hazardous air quality
Less than 4 hours of indoor candle or wood burning daily significantly increased daily exposure to potentially hazardous, combustion-derived carbonaceous particulate matter among older residents in Northern Finland, according to findings recently published in Indoor Air.
“In developed countries there are still a limited number of studies where personal and indoor determinants of wood burning are studied,” Taina Siponen, of the National Institute for Health and Welfare, Kuopio, Finland, and colleagues wrote, adding that residents of these areas spend most of their time inside.
Researchers measured indoor exposure to fine particulate matter (PM2.5) — regarded as the “most important environmental risk factor” when determining disease burden — and its light absorption coefficient (PM2.5abs) — a proxy for combustion-derived black carbon — among 37 older residents in a Northern Finland city that has low ambient air pollution levels. Participants spent an average of 92% of their time indoors during the 6-month winter-spring study.
Siponen and colleagues found that wood burning via masonry heater, wood-fired sauna stove or recreational open fireplace lasted an average of 2.3 hours daily and increased a participant’s PM2.5abs by 9%, indoor PM2.5abs by 7% and indoor PM2.5 exposure levels by 20%. Candle burning lasted an average of 3.6 hours daily and increased a participant’s PM2.5abs levels by 8% and indoor PM2.5abs by 10%. Cooking with electric stoves and/or ovens was linked to increased levels of indoor PM2.5, but there was no link between this activity and personal exposure to PM2.5 or PM2.5abs.
Researchers also found that homes with natural ventilation — where building air supply and extraction are based on pressure differences inside and outside the building — had higher levels of hazardous particles. – by Janel Miller
Disclosures: The authors report no relevant financial disclosures.
Perspective
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This study by Siponen et al, helps bring attention to human indoor air quality behaviors. These researchers also looked at black carbon levels (the PM2.5abs measurement), which allows for measurement of organic carbon compounds that accumulate after incomplete combustion of fossil fuels or from burning of biomass materials such as wood. It allows for identification of sources of such pollutants more clearly as demonstrated in this study where sources were found to be candle burning and wood stove burning. This helped to contrast from general air pollution of PM2.5abs from outdoor and more distant sources than more immediate indoor sources.
Not all personal indoor proximate measures are identical to the backpacks the participants in this study wore. This suggests that indoor proximate exposures can be influenced by your individual surroundings and behaviors. Heating from burning biomass can be an issue if there is not proper ventilation. In addition, people at most risk for chronic heart and lung conditions can avoid candle burning or avoid being close to wood burning, however some exposure will necessarily still occur.
In general, alternative means of heating that are cleaner than wood stove room heaters or wood-fired sauna stoves should be explored and disseminated. If this happens to be a necessary source of heat and alternatives are unavailable, vulnerable people with heart and lung problems and children should avoid prolonged exposures as well as allow proper ventilation. High exposures to black carbon levels can easily occur with exposures to wood and candle burning and knowing this information from the study will help any person with these exposures in the home correlate their symptoms to these risks long and short-term and encourage them to alter their exposures.
Siponen and colleagues’ research also highlights that common behaviors of candle burning as well as biomass burning for heating or cooking are readily available but at the same time pose potential short and longer-term health effects more than might be recognized.
Cleveland Clinic Lerner College of Medicine
Case Western Reserve University