Avoid Wood Smoke

By Roy L Hales

According to the Daily Mail, “Wood-burning stoves emit six times as much pollution as a diesel truck.” The Environmental Protection Agency states wood smoke contains several toxic air pollutants including: benzene; formaldehyde; acrolein, and polycyclic aromatic hydrocarbons (PAHs). Health Canada claims, “In communities where wood heating is common, wood smoke can be responsible for as much as 25% of the airborne particulate matter.” They advise people to avoid wood smoke.

Winter pollution by Bill Smith via Flickr (CC BY SA, 2.0 License)

Wood Smoke Affects Everyone

“Wood smoke affects everyone, but children are especially vulnerable, in part because their respiratory systems are under development. Pregnant women exposed to wood smoke may have children with smaller lungs, impaired immune systems, decreased thyroid function and changes to brain structure that may contribute to difficulties with self control. Children who are hospitalized for lower respiratory tract infections are more likely to have a wood stove in the house, although other factors may also play a role,” writes Dr Michael Mehta, professor of geography and environmental sciences at Thompson Rivers University in Kamloops, BC.

“The elderly are also at risk. A recent study of people living in B.C., in Kamloops, Prince George, Courtenay and the Comox Valley, showed that wood stove pollution significantly increased the rate of heart attacks in people over 65.”

Worse Pollution Than Urban Areas

Mehta claims that air pollution is sometimes worse in BC’S rural areas than the province’s urban centres. 

The city of Montreal recently banned wood stoves and fireplaces, unless they emit “no more than 2.5 grams of fine particles per hour.” Prior to that, wood smoke was allegedly responsible for “900 premature deaths per year on the island of Montreal, more than 6,000 cases of bronchitis in children, 40,000 asthma attacks and almost 300 emergency visits to hospitals for other respiratory and cardiac problems.”

Switch To A Cleaner Fuel – Like Oil???

Only low emissions wood stoves with permits are allowed in Montreal, but “propane or natural gas stoves and fireplaces are OK. You don’t have to declare them, and you can continue to use them.”

Similarly, Health Canada advises people to “switch to a different source of heating, like natural gas or oil.”

Are Wood Stove Users Enviro-Villans?

So, are wood stove users just as guilty of polluting the environment as oil companies?

To put this question into context, trees have often been called the lungs of our planet. They absorb carbon as they grow and release it when they decompose. Rotting wood enriches the soil. Burning wood releases about 20% more carbon than leaving a tree to rot on the forest floor.

As this carbon can be recaptured by introducing more trees, Scott Pruitt’s Environmental Protection Agency classified burning wood as environmentally neutral.

Not so fast, argues William Schlesinger, president emeritus of the Cary Institute of Ecosystem Studies and an EPA Science Advisory Board member:

“The big problem is you’re cutting old-growth forests and expecting them to regrow. That’s totally unrealistic in 20 years and not guaranteed over 100 years.”

(However a researcher in the energy sector[1] told me that though wood produces as much CO2 as coal, Cortes Island’s sustainable forestry practises more than compensate for this.)

Selectively Cutting Firewood

ECOHome frames the problem on a more personal level and suggests homeowners selectively cut their firewood:

” … If you are in a rural area there are always dead trees that need to come down … they might as well warm you instead of rotting. Selectively choosing trees for firewood rather than clear-cutting a portion of a forest will have a lower environmental impact. While we found no truly reliable claims on the net, consensus seems to be that you can sustainably harvest between 1/2 and 1 face cord a year from an acre of land, more if you include deadfall.”

Avatar Grove, outside Port Renfrew BC, was originally slated to be clear cut – Roy L Hales photo

How Much Fuel Do You Need?

As the world switches to more energy efficient homes, in response to climate change, the amount of wood needed will decrease. To quote ECOHome once again, currently:

“An 1,800 sq. ft. house that is poorly-insulated may need an extra-large stove, an 1,800 sq. ft. house that is super-insulated may need an extra-small stove. There are even houses like passive solar homes that could probably be kept warm with a fondue pot and a few mood candles.”

Smoke Pollution

The big question appears to be smoke pollution, which is more of a problem in urban centres like Montreal than remote islands like Cortes.

“Smoke from a wood stove is generated primarily by incomplete combustion. Improving a wood stove’s burning efficiency will improve the combustion process, and thus reduce the amount of smoke and harmful air pollutants released into the air. Burning efficiency is affected by both the design features of the stove, the wood source, and how it is operated and maintained.” – the New Hampshire Department of Environmental Services.

Low Emissions Wood Stoves

Health Canada suggests that people reduce their smoke output by using low emissions wood stoves.

British Columbia’s Wood Stove Exchange Program was set up to help homeowners replace old, smoky wood stoves for cleaner burning wood stoves and other heating options. (Click here to see a list of areas where this program is operating.) People living within the Strathcona Regional District (SRD) are being offered a $250 rebate on the purchase of their new stove. “For more information regarding the program – and to request a refund package – please call the office at 250-830-6700, or send an email to rebates@strathconard.ca.”

Passive Home owners need to go further than that:

“Instead of an open fire place,  an airtight wood stove which receives the combustion air from the outside needs to be used. The stove should be as small as possible as the heating power tends to be much too high in very efficient houses.”

Firewood

Using the right fuel is also important.

Firewood should be ” … seasoned for six to eight months prior to burning and stored under cover for protection from the weather. Wet or freshly cut (“green”) wood is not energy efficient because the heat produced is used to evaporate water, rather than heat the home. The water content of a tree or freshly-cut firewood can be as high as 50%, compared with 15-20% in dry, well-seasoned wood. Burning dry wood produces a more even burn and helps prevent the formation of creosote, a highly-flammable crusty deposit that sticks to the inside walls of your chimney.”

“The use of properly sized split wood piece is equally important. Wood should be split to a maximum thickness of four to six inches, depending on stove size. This size increases the surface area exposed to flame, resulting in higher burn efficiency.”

Top photo credit: Fire in the Wood Stove by Stanze via Flikr (CC BY SA, 2.0 License)

Footnote

[1] I have not named the researcher because his comment was made in a conversation, rather than an interview, and might have been framed differently had he known it would (eventually) appear in print.

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