LETTER: Wood fires--wholesome or hypocritical?

LETTER: Wood fires--wholesome or hypocritical?

Dear Editor,

I’ve just been reading your story “Only YOU can prevent cancer now” and can support wholeheartedly the mission of the PCN (Prevent Cancer Now) campaigners.

What I find ironical though, and even hypocritical in some instances, is that we often read about campaigns about carcinogens from BPA, tanning beds, nuclear power, coal fired power, cigarette smoking, garden chemicals and weed killers, incineration plants and many other sources of cancer causing chemicals and toxins and yet quite happily ignore a major source in our own towns that we are, or can be, in total control of…wood smoke.

Your story uses the expression “you can’t fight fire with fire”. You can however “fight fire with no fire”…from burning wood.

Wood smoke is known to contain more carcinogens than cigarette smoke. It harms you and your neighbours, especially children and people with respiratory problems. EPA (Environmental Protection Agency) researchers suggest that the lifetime cancer risk from woodstove emissions might be 12 x greater than the lifetime cancer risk from an equal amount of cigarette smoke.

One EPA study concluded that breathing wood smoke on high pollution days is equivalent to smoking 4 to 16 cigarettes.

Another study concluded that a single wood stove operating for an hour and burning 10 lb. of wood will generate 4300 times more carcinogenic aromatic hydrocarbons that 30 cigarettes.

The health risk from wood smoke pollutants is well documented. Wood smoke contains over 100 chemical compounds including many of the same chemical compounds as cigarette smoke including carbon monoxide, nitrogen oxides, hazardous metals, and known carcinogens such as formaldehyde, dioxin, benzene and toluene compounds.

The greatest hazard is from fine particulates less than 2.5 microns in size (a human hair varies in diameter from about 20 to 120 microns). These fine particles can enter homes, even with doors and windows closed and even homes without wood stoves have reportedly been found to reach 50 to 70% of outdoor levels. Moreover, it has been found that these fine particles penetrate deep into the lungs and are long lasting.

Wood burning stoves have been found to be the largest single source of small toxic particles entering our homes, in many cases from neighbours wood stove

A BC Government report says that wood provides about 10% of residential space heating requirements in BC whilst accounting for 97% of the pollution from space heating. . It mentions an air-shed modeling study in Quesnel which determined that the “residential” sector contributed up to 62% of fine particulates.

In the Rossland energy surveys, 7 to 9% of respondents use wood as a primary fuel source and over 50% use wood as a secondary heating source.  A low cost solution to preventing or reducing these carcinogens in the air from wood smoke is quite simple….stop burning wood.

A further incentive to many conservation minded people who burn wood, under the impression that it is carbon neutral, should be the message from a campaign kicked off in February by Hillary Clinton on behalf of a Climate and Clean Air Coalition”. This campaign involves about 6 countries and the United Nations and targets “soot” from wood burning and diesel engines. The particulates or “black carbon”are now considered by researchers to be a significant contributor to global warming in addition to its known health risk.

Ken Holmes




Thanks for all these great points.

While winter air quality in many valley towns really is terrible, depending on the time of day, this issue is much more nuanced - more sides to the story - for rural living. 

Discussing these nuances is most helpful:

- Wood heat feels fabulous and is a great way to heat;
- The fuel is readily available; volunteering around us all the time;
- Where ventilation is good the impact of carbon monoxide, benzene, and fine particulates is greatly reduced.
- Here in the Kootenays, the choice for other fuels has challenges: the electrical capacity may not even exist to convert;
- The cost of conversion can be prohibitive; might be better to focus on new constructions;

Attempting an outright ban might generate needless opposition.

Wood heat resources

Thanks for this discussion, folks! There is more information on the Prevent Cancer Now website - www.preventcancernow.ca. Scroll down a bit on the home page to see the article about wood heating, which links to information compiled by the Canadian Lung Association.



A wood stove by any other name...

Thank you for the valuable points and information.

And please follow Ken's link to donate to Prevent Cancer Now!

I agree, the vast majority of wood stoves gobble wood inefficiently and, consequently, belch out all manner of toxins—those characteristic campfire smells.

But not all wood stoves are created equal, and most toxins can be avoided by intensely hot, turbulent, oxygen-saturated fire on fuels with a high surface area.

Benzene (mentioned in the comment below) has a combustion temperature around 570 deg. C, but a commercial "high-efficiency" stove burns at 600 deg. C, and the masonry stoves of the old continent burn at around 800 deg. C.

Even better, especially for do-it-yourselfers, is the rocket mass heater invented by Ianto Evans. I was fortunate to spend several weeks with Ianto a decade ago to learn how to build cob houses—he also showed us how to build his ingenious burner out of inexpensive materials.

I was astonished how well the stove burns. It literally roars, and it produces no smoke, no ash, no soot, and no smell. Ianto says the combustion chamber reaches 1000 deg. C (1800 F).

It works through a clever use of fluid dynamics and the "chimney effect."

Typically, wood stoves have tall chimneys to generate enough draw from the relatively cool flame. Because the fire's heat isn't stored in much mass, people have to damp down the stove to keep it smouldering all night. This practice generates even more awful chemicals and wastes wood.

Furthermore, the interior shape of most stoves doesn't create a good airflow, especially around the fat logs that are usually stuffed in. So even when there's enough heat, there often isn't enough oxygen to make a complete burn.

Much of the heat that is created leaves the building through the chimney.

Ianto's stove is completely different. It uses small diameter wood and the combustion chamber is narrow, heavily insulated, and has abrupt corners to create turbulence. The heat is so intense that the stack can be short (around 4 feet) and the strong chimney effect pushes the air forcefully.

As a result, the flow can be diverted back down and through standard stove pipe buried into some kind of mass to capture the heat. By the time the air leaves the house, it's just CO2 and water vapour at room temperature.

My nose is quite good, but I couldn't smell a thing, even when  I stuffed my face fully into the outlet in the side of the wall.

There are many ways to heat a house well. Good passive solar design is incredibly effective, so long as the sun beats down on a mass such as a trombe wall. Solar hot water is another good idea. Electricity can be a good way to heat, if you feel good about how the electricty was generated. Natural gas burns clean, but there are a lot of other impacts before it reaches your house.

Ultimately, the best answer to heating is to require less. North America is awash in houses that are too big and leaky.

That all said, there are plenty of people in BC, especially in rural areas, for whom wood heat is the only affordable option. It can be as cheap as their labour and there's plenty of wood out there.

Inexpensive but ingenious solutions such as Ianto's rocket mass heater are a big part of the answer for people in this situation. The only drawback is having to split the wood into slimmer pieces, but people will also use one-third the amount of wood, or less.

Although I would rather see wood turned into mushrooms, insects, habitat, and soil through a long rot, maybe burning it cleanly beats building more hydro dams or drilling for natural gas?

Those interested in rocket stoves should check out Ianto's 2006 book, "Rocket Mass Heaters."

A reader sends in this

A reader sends in this information on the alleged carcinogenic properties of wood smoke:


Beware of the Benzene in the air

Benzene, a Toxic chemical that permeates and pollutes our air, is emitted from industrial sources and from all residential forms of Wood burning.

Benzene, a known carcinogen to humans, destroys the air we breathe in our residential neighbourhood, placing everyone at the potential risk of developing cancer.

Woodsmoke pollutes the surrounding air for miles, seeping into homes, onto property, into lungs and our cells doing irreparable damage.

Woodburning stoves, Wood burning fireplaces, pellet stoves, pellet factories, OWBs and outdoor open air burning contribute to the toxic air we breathe daily.

Benzene Facts:
Will benzene cause cancer?
The International Agency for Research on Cancer (IARC) has concluded that there is sufficient evidence for carcinogenicity to humans. The overall IARC evaluation is Group 1 - carcinogenic to humans. The National Toxicology Program (NTP) has determined that benzene is a substance known to be carcinogenic. The American Conference of Governmental Industrial Hygienists (ACGIH) has designated benzene as a confirmed human carcinogen (A1). There are common limitations in the human studies because exposures usually cannot be accurately assessed, the numbers of cases is small and frequently there is exposure to other chemicals. However, there are so many case reports and epidemiologic studies of exposed workers, that a causal relationship between benzene exposure and leukemia has been clearly established. Benzene exposure has also been associated with cancer of the lymph system (lymphoma), lung cancer and bladder (urothelial) cancer.
Benzene also damages the bone marrow, where new blood cells are produced, resulting in aplastic anemia, which can lead to leukemia.

"The tragedy of benzene is that it has taken so long for science to be translated into protective action. Many thousands of workers and other persons in nations around the world have suffered unnecessarily and died prematurely while regulatory agencies, industry and the courts debated the carcinogenicity of benzene and argued about the need for protective regulation. In the current era of global proliferation of toxic chemicals and hazardous technologies, all who are involved in the production and use of benzene have a heavy responsibility and a duty to protect their workers and the general public against this highly toxic and carcinogenic compound. The debate over whether benzene is carcinogenic has long since ended, and controversy about the need to protect humans against benzene must not continue."
- Dr. Philip Landrigan
Chair of Community Medicine at Mount Sinai Hospital, New York
Editor-in-Chief, American Journal of Industrial Medicine

Environment Canada States:
“Benzene has been classified as carcinogenic to humans. It is a non-threshold toxicant - a substance for which there is considered to be some probability of harm for critical effects at any level of exposure. The main sources of benzene are:

•       wood combustion (including forest fires and residential wood combustion);”

Bans to prohibit the use of all residential Wood burning devices and appliances must be adopted via by-laws and regulations to protect all Canadians from the cancer causing chemical Benzene and all toxic chemicals in Woodsmoke.

From Linda Baker Beaudin, founder of the group Air Is Precious.

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