Indoor air quality and wood heat
Hi All,
The primary source of heat for my home is a wood stove. This is an economic choice (cord wood is free) but I sometimes wonder if it is a healthy choice.
Wood stoves produce some nasty stuff. Conventional wisdom says that everything goes up the chimney, out of the house and stays out of the house. This seems like it might be an oversimplification. Wood stoves depend on draft to keep the nasty stuff out of the house and draft is not entirely reliable. Once the nasty stuff makes it out of the house, there are routes for (some of it) it to come back in.
Is anyone aware of studies on indoor air quality in homes that heat with wood ? I spent some time googling around and found lots of info on wood stoves and regional air quality but nothing that pertains to the impact on air quality inside the house where a modern wood stove is located. Surely this issue must have been examined and quantified by someone.
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Replies
Pierre,
I'm not aware of any studies that look at modern wood stoves and indoor air quality, but perhaps a GBA reader will provide a link.
There have been studies of the health effects in developing countries of cooking over open wood fires. The effects are not good. It is generally assumed that the use of a stove and a chimney mitigate these negative health effects.
-- Martin Holladay
Here is an EPA page with a number of links on wood heat and indoor air quality: https://www.epa.gov/indoor-air-quality-iaq/wood-smoke
Woodstoves that have combustion air ducted directly to the firebox (not a "proximity vent", that is open to the room air) will in theory deliver less combustion products into the room air in the event of a backdraft. No wood stove is 100% air tight, and the door gaskets and general sealing of the cast iron / steel / stone / ceramic parts may still leak some, but it still has to be better than a wood stove drawing combustion air directly from the indoor air.
There is also the issue of ash clean out. Doing this maintenance in the light of direct sun through a window will reveal the explosion of particulates it creates to the inside. Flushing with a well placed fan and open windows during clean out should help.
I was searching GBA for any new IAQ solutions when I came across your question.
From my experience in our neighborhood, your neighbors will be affected considerably more from your use of a wood stove, than you yourself.
Generally, the chimney will efficiently exhaust but your neighbours get the fallout.
I live in a neighborhood with a lot of wood heat, and when the conditions are right for the smoke to linger, it can be quite bad. Even if the chimney works well to make sure the smoke all goes up the chimney, when the air in the immediate area is dirty, a stove user will be drawing in at least as much outside air as a typical house and the air inside won't be better than outside, without aggressive filtration.
A paper was just published that addresses the original question...
https://www.mdpi.com/2073-4433/11/12/1326
From the abstract:
"Taken together, the study demonstrates that people inside homes with a residential stove are at risk of exposure to high intensities of PM2.5 and PM1 within a short period of time through normal use. It is recommended that this risk be reflected in the testing and regulation of residential stoves"
The guardian summarizes the study here:
https://www.theguardian.com/environment/2020/dec/18/wood-burners-triple-harmful-indoor-air-pollution-study-finds
Is concern specific to wood I wonder, or just combustion appliances in general?
I'm not familiar with natural gas heat, but when our oldish oil boiler kicks on in the basement, oil can definitely be smelt in the basement.