Editor's Note: This article is the third in a series the Citizen will be publishing in partnership with the provincial Ministry of the Environment and the Cowichan Valley Regional District about the importance of clean air the effects of pollution.
People like to heat with wood because it's a renewable resource, and much less expensive compared to other heating options. As well, while estimates of the amounts differ, using wood produces far less greenhouse gas compared to furnace oil or natural gas. On the other hand, even pellet stoves, the cleanest wood burning option, can produce almost 40 times more fine particulate pollution than an oil furnace and 60 times more than a natural gas furnace - EPA certified woodstoves and non-certified woodstoves emissions are hundreds of times higher.
Wood smoke is a sign of inefficient burning and contains many hundreds of harmful gases and chemicals, just like cigarette smoke or vehicle exhaust. Nitrogen dioxide is a lung irritant, as are many of the polycyclic aromatic hydrocarbons, aldehydes, phenols and quinones that are present in woodsmoke. Some are known to cause cancer in humans - dioxins, formaldehyde, benzene, and benzo[a]pyrene, to name a few.
Breathing woodsmoke is not guaranteed to give you cancer - but it adds to the overall burden of exposure to pollutants from many sources.
For some people, this might result in cancer.
The International Agency for Research on Cancer recently classified fine particulate air pollution as a known carcinogen, based on substantial evidence provided from studies around the world.
On balance, it's hard to know which heating option provides the highest net benefit. Do reductions in greenhouse gases and financial savings for some offset increases in local particulate pollution, health impacts and potential medical costs?
The answer may depend on who you ask, but taking reasonable actions to reduce the impacts of wood smoke pollution makes sense.
Real-life tests suggest that the toxicity of wood smoke can vary a lot, depending on how you operate your woodstove. Lack of air supply creates the most toxic smoke, followed by loading too much wood. Other tests have shown that moist wood (higher than 30 per cent dry basis moisture) produces more fine particulates. This means that even if you have a new, certified woodstove, using it incorrectly can make it no better than older high polluting woodstoves.
The amount of smoke coming out of your chimney shows how well your woodstove is operating.
Ideally there should be very little visible smoke within 15 minutes of starting or refueling your fire. Visit the CVRD website (www.cvrd.bc.ca/index.aspx?NID=1466) to get more information on how to check the moisture level of your wood, and how to check the amount of smoke coming out of your chimney to see if you are burning efficiently.
Also, consider upgrading your old woodstove in 2015 with a rebate from the CVRD, and improve air quality for you and your neighbours. Pellet stoves are the cleanest option, and using a HEPA air filter can help reduce your exposure indoors.
Eleanor Setton is a research scientist at the University of Victoria. Contributions were also made by the Cowichan Valley Regional District and the B.C. Ministry of Environment.