A Danish study shows that all wood burning appliances are far dirtier than other sources of heat and even dirtier than a 10 year old truck without a filter (Look for the full report “Pollution from Residential Burning: Danish experience in an international perspective” on the Clean Heat information page).
Real world emissions much higher than factory tests
The Danish study tested these wood burning appliances under “ideal operational conditions”. However, the authors note that “in reality emissions are most likely significantly higher.”
A 2005 study, Real-life emissions from residential wood burning appliances in New Zealand, suggests that real world use may result in emissions 4 to 5 times higher than factory emission ratings.
So the new BC standard for 2020 of 2.5 grams/hour stove, is more likely to mean the release of 10-12.5 grams/hour of fine particulates per new stove.
There is a lot of emphasis being put on the new ‘clean’ standards wood stoves will need to meet by 2020 and on how switching to these new stoves will supposedly make a difference.
But as noted above and in other studies, factory tests do not reflect real world use. And on Vancouver Island, our higher humidity and wetter wood is likely to result in emissions that are far higher than stated.
Fine particulates are costly
As the Danish study notes,
“[P]ollution from wood burning in Denmark contributes with about 50% of all health damages from Danish pollution sources corresponding to a total health cost in Denmark of around 800 million euros a year. This makes pollution from wood burning the most expensive environmental problem in Denmark harming Danes several times more than fine particles from domestic road traffic.”
In wood smoke impacted communities in BC, there is no reason to think that the relative health costs and impacts would be much different.
Exchange programs not the solution
The answer to cleaner air likely doesn’t include installing more or different wood stoves.
In Libby, Montana, a $2.5 million wood stove exchange program had mixed results. As noted on the Doctors and Scientists Against Wood Smoke Pollution website:
approximately 80% of Libby’s winter particulate pollution came from residential wood burning. After the changeout, wood stoves still accounted for approximately 81% of Libby’s particulate pollution, although there was a reduction in total PM2.5 mass.
Ultimately, after an initial reduction, levels of toxic [Polycyclic Aromatic Hydrocarbons] remained the same after the changeout as before.
Four years after the end of the exchange, “highly variable” levels of emissions across homes that had received new certified wood stoves. Some houses did not ultimately experience any reduction in PM2.5 at all.
If we really want to make a difference in our air quality, we need to stop financing rebates for people to install newer wood stoves, and direct those resources instead to providing more and better incentives for gas and heat pumps.