Heating with wood: not as “environmentally safe” as you might think!

Développement durable, Environnement, Faune et Parcs

Wood heating

Other documents

Regulation respecting wood-burning appliances (French)

Brochure - Heating with wood : How harmless is it? (PDF file, 518 Kb)

Campfire impact on air quality (French)

For most of us, a fireplace means a quiet evening spent relaxing in front of the fire, watching the dancing flames and listening to the crackling logs.

But at what cost?

Whether the smoke released comes from a woodstove, a fireplace or a campfire, it is not as “environmentally safe” as you might think. According to Environment Canada, a woodstove that is not certified emits as many fine particles into the air in nine hours as does a certified woodstove in 60 hours or a mid-size automobile traveling 18,000 km.

Heating with wood represents a major source of contaminant discharge in the air: carbon monoxide (CO), volatile organic compounds (VOC), fine particles (PM_2.5), nitrogen oxides (NO_x) and polycyclic aromatic hydrocarbons (PAH). Smoke from the combustion of wood is present both inside and outside the home.

In residential neighbourhoods where wood heating is common, exposure to contaminants from chimney smoke can have a significant impact on health.

Québec situation

In Québec, wood-fire home heating is responsible for half of the fine particle emissions associated with human activities. At the local level, wood combustion may contribute far more severely to pollution. For example, a wood-heating sampling campaign carried out in Montréal in 1999 (in french) by the Montréal Urban Community has shown that, in winter, the concentrations of fine particles, VOC and PAH were often higher in residential neighbourhoods than in downtown Montréal. Under certain weather conditions, the concentration of contaminants in the ambient air can reach high levels in certain neighbourhoods. This type of situation can occur in many places in Québec.

The number of wood-heating systems is increasing in Quebec. Statistics Canada data indicate that the number of dwellings using wood heating increased by about 60% from 1987 to 2000. During the same period, the number of dwellings increased by less than 20%.

Number of dwellings using wood heating in Québec

Number of dwellings using wood heating in Québec - Source: Statistics Canada
Source: Statistics Canada

Health Effects of Smoke

The particles emitted when heating with wood are very small, less than 2.5 microns, allowing them to penetrate deep into the respiratory tract, affecting breathing.

Potential health impacts of certain contaminants from high concentration of wood smoke in the air

Contaminants		Effects
Carbon monoxide	CO	Headaches, nausea, dizziness, aggravation of angina in people with cardiac problems
Volatile organic compounds	VOC	Respiratory, irritation and difficulties, certain VOC are carcinogenic (ex : Benzene)
Acrolein and formaldehyde	---	Irritation of the eyes and respiratory system
Fine particles	PM_2.5	Irritation of the respiratory system, aggravation of cardiorespiratory diseases, hastened mortalities
Nitrogen oxides	NO_x	Irritation of the respiratory system, painful inhalation, coughing, pulmonary oedema
Polycyclic aromatic hydrocarbons	PAH	Certain PAH are considered or suspected of being mutagenic or carcinogenic
Dioxins and furans	---	Potentially carcinogenic

Source: Direction de la santé publique de Montréal-Centre

The magnitude of these effects depends upon people’s sensitivity. Very young children, the elderly and individuals who suffer from asthma, emphysema or heart problems are among the most sensitive to air pollution.

Indoor Air

In addition to emitting contaminants outdoors, wood combustion units may alter the quality of the air inside the home when a portion of the combustion gases and fine particles make their way back indoors. These leaks inside the home will vary in importance according to the type of unit used, the quality of its installation and the way in which the homeowner operates the unit. A study carried out by the Direction de la santé publique de Montréal-Centre showed that people using a woodstove had higher concentrations of contaminants in their urine than people without woodstoves. The combustion of wood thus represents an additional source of exposure to toxic substances in the home.

What Should You Do?

A few simple things you can do to limit your exposure to pollutants:

How	Why
Avoid burning wood as your main source of heat.	Other heating methods such as electricity, natural gas, and fuel oil pollute less.
Limit the use of fireplaces and woodstoves, especially on smoggy days. Even where they are not prohibited, limit outdoor fires (campfires, leafburning, etc.).	To reduce the amount of pollutants emitted into the air, both indoors and out.
When you heat with wood:
Do not burn household waste such as plastics or treated or painted wood.	To reduce the emission of highly toxic pollutants such as dioxins and furans.
Depending on the availability of resources, use hardwoods (oak, maple, or birch) that have dried for at least six months rather than soft woods like fir, pine, or spruce.	To reduce the amount of pollutants emitted into the air and limit the buildup of creosote in flue pipes that is a common cause of chimney fires.
If you’re thinking of buying a fireplace or woodstove:
Make sure the appliance meets your actual needs, and avoid purchasing an appliance with an excessive heating capacity.	To conserve energy and to avoid the unnecessary emission of pollutants into the air, both indoors and out.
Opt for an electric heating stove or fireplace. Some models can be inserted into existing appliances.	Electricity does not emit pollutants.
If you still decide to purchase a woodstove:
Purchase a certified appliance that complies with the Regulation respecting wood-burning appliances.	For example, new, certified woodstoves can emit up to 90% fewer particles than “conventional” woodstoves.
Choose an appliance whose specifications indicate the lowest particle emissions rate.
Installation Comply with Canada’s Installation Code for Solid Fuel–Burning Appliances.	Proper installation is safer for you and your family and helps ensure your appliance operates as it should.
Upkeep Maintain, repair, or, if necessary, replace your wood-burning appliance.	Over time, wood-burning appliances and chimneys become less airtight and begin to leak gas and particles. This not only reduces their efficiency, it can also deteriorate air quality inside your home. Regular chimney cleaning promotes optimal combustion and minimizes the risk of a chimney fire.

To Find Out More…

Many sites deal with the issue of wood heating:

From the beginning of December to mid-April, the Info-Smog Program informs the public about atmospheric dispersion conditions in southern Québec. When the dispersion forecast is poor, it is strongly recommended that wood heating be avoided.

Residential Wood Heating - Summary of Results from 1999 to 2002
Réseau de surveillance de la qualité de l'air de la ville de Montréal (in French)
Direction de l'environnement et du développement durable de la Ville de Montréal (in French)
Ministère de la Santé et des Services sociaux (in French)
Direction de la santé publique de Montréal (in French)
Environment Canada
Office of Energy Efficiency
Association pour l'air pur (in French)

Brochure - Heating with wood : How harmless is it? (PDF file, 518 Kb)