Wood Burning

Wood Burning and Air Emissions

Wood heating has a long history in Canada and, with new wood-burning technologies and higher energy and heating prices, more households are returning to using wood as a source of renewable energy.  In Canada, wood is burned in more than 3 million homes as a primary or secondary source of heating. Woodstoves are, by nature, a relatively high-polluting source of heat, and they contribute to winter smog in urban and rural areas. When burned properly, sustainably harvested wood from well-managed woodlots can be an effective fuel for home heating.  However, poor practice and older inefficient burning appliances rarely allow for complete combustion and a by-product is unburned fuel or wood smoke.

Wood smoke is made up of a complex mixture of air harming chemical substances including PM10, PM2.5, volatile organic compounds (VOCs), sulphur oxides (SOx), nitrogen oxides (NOx), carbon monoxide (CO), carcinogenic compounds (polycyclic aromatic hydrocarbons, benzene, formaldehyde, dioxins), carbon dioxide (CO2) and water vapour.  Burning inappropriate wood and garbage such as plastic, diapers, coated cardboard, magazines, painted or treated wood, particle board etc. can release hazardous toxins. Toronto Public Health (2002) estimated that residential wood burning accounts for 11 percent of the PM2.5 found in Ontario’s air, 0.8 percent of the total particulate matter (TPM) and 15 percent of the VOCs.

The most efficient wood/pellet burning appliances utilize advanced combustion technology and are rated as low emissions by the CSA/EPA. There have been great improvements on traditional conventional fireplaces and wood stoves manufactured since 1990 as evidenced in the accompanying Table 1.

Appliance CO NOx SOx VOC TPM PM10 PM2.5
Fireplace; Advanced Technology 70.4 1.4 0.2 7.0 5.1 4.8 4.8
Fireplace; Conventional Without Glass Doors 77.7 1.4 0.2 6.5 19.3 18.5 18.4
Fireplace; Conventional With Glass Doors 98.6 1.4 0.2 21.0 13.5 13 12.9
Central Furnace/Boiler (inside) 68.5 1.4 0.2 21.3 14.1 13.3 13.3
Central Furnace/Boiler 68.5 1.4 0.2 21.3 14.1 13.3 13.3
Central Furnace/Boiler (outside) 68.5 1.4 0.2 21.3 14.1 13.3 13.3
Fireplace Insert; Advanced Technology 70.4 1.4 0.2 7.0 5.1 4.8 4.8
Fireplace Insert; Catalytic 70.4 1.4 0.2 7.0 5.1 4.8 4.8
Fireplace Insert; Conventional 115.4 1.4 0.2 21.3 14.4 13.6 13.6
Woodstove; Advanced Technology 70.4 1.4 0.2 7.0 5.1 4.8 4.8
Woodstove; Catalytic 70.4 1.4 0.2 7.0 5.1 4.8 4.8
Woodstove; Conventional 100 1.4 0.2 35.5 24.6 23.2 23.2
Woodstove; Conventional, Not Air-Tight 100 1.4 0.2 35.5 24.6 23.2 23.2
Woodstove; Conventional, Air-Tight 115.4 1.4 0.2 21.3 14.4 13.6 13.6
Other Equipment 115.4 1.4 0.2 21.3 14.4 13.6 13.6
Pellet Stove 8.8 1.4 0.2 1.5 1.2 1.1 1.1

(WLAP, 2005)

Even advanced, efficient and cleaner burning appliances will result in harmful emissions when improperly installed, maintained or operated.  Ultimately, the fuel wood itself must be clean and properly seasoned.

Wood Burning and Regulations

Wood burning is subject to a variety of laws, regulations and standards depending upon jurisdiction:

  • Federal – safety standards for appliances sold in Canada by the Canadian Standards Association (CSA); standards for low emission appliances developed by U.S. Environmental Protection Agency (EPA)
  • Fire Protection and Prevention Act giving rise to the Ontario Fire Code regulates indoor appliances and installation and open air burning (O. Reg.213/07 Article
  • Ontario Building Code – regulates construction of fireplaces, indoor appliances and installation
  • Municipal By-Laws – regulate the use of indoor appliances

A number of Canadian and U.S. jurisdictions are reviewing the practice of wood burning for residential heating. Federally, standards for low emitting wood burning technologies are in place and proper burning practices are promoted through outreach programs. The City of Montréal has adopted a by-law banning the installation of wood burning appliances in new or existing buildings, except for wood pellet burners.  There have even been legal cases involving neighbours, health and wood burning stoves.

Open Air Burning

Open air burning is highly polluting, contributes to poor air quality and poses real risk to human health and safety Furthermore, backyard burning of waste is illegal and bonfires and burn barrels needlessly emit significant amounts of dioxins and furans into the environment.

The Ontario Fire Code (O.Reg.213/07 Article prohibits all open-air burning unless approved by the Chief Fire Official. In Hamilton it is illegal to open air burn except as outlined in the City of Hamilton Open Air Burning By-Law # 02-283. The by-law restricts outdoor burning to clean wood and brush (not garbage) in designated rural areas only after acquiring a permit. It regulates fire location, size, timing, safety and deems the use of a chimnea or other outdoor fireplaces as open air burning. The open air burning regulations apply to farms and also prohibit burning on declared smog alert/smog advisory.

If you have any questions regarding open air burning or pemits, contact Hamilton Emergency Services – 905- 546-3346 or fire_department@hamilton.ca

Some Wood Burning Do’s and Don’ts


  • Burn only small pieces of, clean dry wood. – Use a mix of hardwoods & softwoods.
  • Burn the fire hot & refuel more often with smaller loads.
  • Keep your chimney clean. Frequently remove the ashes from your appliance.
  • Keep your home well insulated to prevent heat loss & to increase energy efficiency.
  • Replace old inefficient wood burning appliances that don’t comply with pollution standards.


  • Don’t burn garbage of any kind
  • Don’t burn painted, treated, or wet wood.
  • Don’t store your wood where there is water or moisture.
  • Don’t fill a stove to more than half of its capacity.
  • Don’t let a fire smoulder overnight & don’t dampen down your fire.
  • If possible, avoid using wood combustion as your main source of home heating.
  • Don’t allow creosote to build up in your chimney.
  • Don’t use your burning appliance when a Smog Warning is in effect in your area.

More Information

Health Canada: Residential Wood Smoke

Hamilton’s Open Air Burning Policy

Montreal Wood Burning