Table of Contents

A burning reality: Managing the health risks of residential wood smoke

Ryan Huff

Feb 19, 2025

Wood smoke composition and indoor exposures

Wood smoke is a complex mixture of particles and gases, including substantial quantities of fine particulate, PM_2.5. Wood smoke also contains gases such as carbon monoxide (CO), nitrogen oxides (NO_x), and other pollutants such as dioxins, furans, volatile organic compounds (VOCs) such as benzene and formaldehyde, and polycyclic aromatic hydrocarbons (PAHs). Many of these pollutants are found at higher levels in homes with wood-burning appliances and their surrounding communities. For example, several studies have demonstrated that indoor PM_2.5 levels are 20 - 123 % higher in homes with wood-burning appliances.

Health effects of wood smoke

Exposure to wood smoke pollutants can have serious acute and chronic health effects. PM_2.5 particles can penetrate deeply into the lungs, where they cause irritation and inflammation. Short-term exposure to wood smoke can induce headaches, nausea, dizziness, irritation of the eyes, nose, throat, and lungs. Short-term exposure has also been associated with reduced lung function, and increased risk of severe events such as strokes and heart attacks. Long-term exposure has been associated with increased risk of developing chronic conditions such as heart and lung diseases.

Both short- and long-term exposures have been associated with worsening of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD), including increased emergency room visits, hospitalizations, and premature deaths. Pregnant people, infants, children, older adults, and those with chronic health conditions are the most susceptible to the effects of wood smoke.

There is no health-based limit for indoor concentrations of PM_2.5, and the current Canadian residential indoor air guidance recommends keeping levels as low as possible. However, some homes have been measured to have PM_2.5levels above the outdoor Canadian Ambient Air Quality standard of 27 µg/m² (24-hour average).

Use of wood-burning appliances across Canada

A 2019 Statistics Canada survey on residential wood burning reported that 19% of Canadian households burn wood or wood pellets at their primary dwelling for heating or cooking. This usage equates to an estimated 3,905,861 full cords of wood and 196 million kg of pellets. By province, Newfoundland and Labrador reported the largest percentage of wood- or wood pellet-burning households at 32% and Ontario the smallest at 14% (territorial data not reported). It is important to note that in 2021 an estimated 7% of rural (non-census metropolitan areas) households in Canada used wood or wood pellets for their primary source of heating compared to 1% of census metropolitan areas. Of BC residents surveyed about the reasons for using a wood-burning appliance, 52% indicated reliability in the event of a power outage and 42% indicated the availability of wood supply. These factors are important when considering policies and practices aimed at lowering the levels of residential wood smoke in and around the home.

Reducing exposure to wood smoke indoors

Several best burning practices are recommended by Health Canada and the Canadian Lung Association to reduce exposure to wood smoke in the home. These include:

Only burn seasoned wood (split and dried for at least 6 months). Green or wet wood produces significantly more smoke.
Dry wood outdoors. Drying wood inside adds excess humidity to the home that could lead to mould and mildew growth.
Do not burn garbage, plastics, foam containers, particle board, or painted or sealed wood because these can release toxic gases into the home and surrounding community.
Do not burn driftwood from the ocean. Wood that has been in saltwater produces smoke with carcinogenic dioxins and furans.
Perform regular stove/fireplace maintenance according to manufacturer's instructions, including cleaning chimneys and flues regularly to ensure proper air flow and ventilation. Have appliances professionally inspected at least once a year.
Use dampers if available to control the ventilation, maximizing heat output and reducing the amount of wood needed for heating.
Consider using an indoor air purifier to reduce ambient wood smoke pollutants. These devices can achieve greater than 50% reductions in PM_2.5 indoors.
Install and maintain smoke detectors and a carbon monoxide alarm in the home.
Consider using a low-cost PM2.5 sensor to assess levels of exposure in the house when using appliances.

Replacing wood-burning appliances

In addition to good burning practices, changing out old stoves for heat pumps, pellet stoves, or cleaner wood stoves can reduce exposure to wood smoke pollutants. For new wood-burning appliances, the Canadian Code of Practice for Residential Wood Burning Appliances recommends using only low-emission Canadian Standards Association (CSA) or the US EPA certified units. These appliances burn hotter and emit less pollution both inside the home and out into the community.

It is not known how many wood-burning appliances across Canada are low emission certified. However, in BC it is estimated that only 67% of fireplace inserts and 65% of wood-burning stoves are low emission certified. Many jurisdictions offer change-out programs for replacing old appliances, and support initiatives to raise awareness of good burning practices, and educate the public about wood smoke and its health effects. These include:

British Columbia: Community Wood Smoke Reduction Program – Incentivizes replacing old wood stoves, supports educational initiatives, and funds local program administration and promotion.
Nova Scotia: Efficiency Nova Scotia Home Heating System Rebates – Provides up to $500 and $1,000 in rebates for replacing wood stoves or boiler systems respectively with low emission certified models.
Yukon: Home Heating System Rebate - Provides up to $800, $600, and $300 in rebates for the purchase of low emission furnaces or boiler systems, pellet stoves, or cord wood stoves respectively.
Northwest Territories: Arctic Energy Alliance Rebate Program - Provides up to 50% of the purchase cost to a maximum of $2,000 in rebates for replacing wood or pellet stoves with low emission certified models.
New Brunswick: New Brunswick Power Total Home Energy Savings Program - Provides up to $200 and $500 in rebates for replacing wood stoves or furnace boiler systems respectively with low emission certified models.
Quebec City: RVQ 2950 Program for the removal or replacement of non-certified or first-generation certified solid fuel appliances – Grants up to 90% or up to a maximum of $1,000 of the cost of replacing wood or pellet appliances with low emission certified models.

Reducing wood smoke in the community

Other policies and regulations across all levels of government are also helping to reduce residential wood smoke emissions. For example, the National Building Code of Canada specifies EPA or CSA certification of solid-fuel burning space-heating equipment. In addition, a 2012 review by the Government of Canada identified policies and regulatory instruments related to residential wood burning across the country. For example, the Solid Fuel Burning Domestic Appliance Regulations in BC and the Air Pollution Control Regulations in Newfoundland and Labrador ensure that only low-emission certified appliances can be sold by vendors.

At the local level, many communities now have by-laws to reduce wood smoke emissions. In Metro Vancouver, for example, wood-burning appliances must be registered by September 2025 and comply with performance standards. Use is prohibited (with exceptions for sole heat source residences and emergency situations) annually from May 15^th – September 15^th and wood-burning appliances are prohibited in new buildings. Similar regulations have been introduced in Montreal, requiring declaration and the use of only low emission certified of appliances. In addition, during smog warnings all use is prohibited in the city. However, these regulations present challenges in more rural areas where many residences have less access to other heating sources. In these situations, different by-laws aimed at reducing wood smoke emissions may be more effective. For example, a bylaw recently passed in Gibsons is designed to identify homes producing excessive smoke.

For any community considering policies or regulations to reduce the air quality impacts of residential wood burning, PM_2.5 monitoring is a crucial first step in understanding wood smoke exposures. Communities can be affected by residential wood smoke in very different ways that do not necessarily correspond with the number of wood-burning households. For example, weather patterns and mountainous topography in some regions can trap smoke in valleys and intensify the outdoor pollution levels. Real-time outdoor air quality information including the Air Quality Health Index (AQHI) from the government of Canada is available to many communities. However, for communities without PM_2.5 monitoring stations, the AQ Map, consisting of a network of low-cost sensors, may be a helpful tool in understanding current air quality. For indoor air pollution, low-cost PM_2.5 sensors can help assess exposure levels. Understanding the scope of the issue is vital in employing appropriate solutions to protect public health.

More information on guidelines, standards, best burn practices, and health risks specific to residential wood smoke are listed below: