Professor, Geography & Environmental Studies
Thompson Rivers University
IT MAY BE natural, but there’s nothing safe or environmentally sound about heating your home with wood or clearing debris and yard waste in a burn barrel or pile.
Many communities around North America and elsewhere are grappling with how best to manage exposure to wood smoke, and to understand more fully the community level and individual impacts associated with this serious and growing environmental health risk issue.
Currently 1 in 9 deaths on a global scale are due to air pollution. In Canada, air pollution kills nine times more people than automobile accidents. In many rural communities in British Columbia, the main source of air pollution is from wood burning practices at the residential level. In some city neighbourhoods, wood smoke wafts around houses and moves through walls with ease given the small size of the particles contained within it.
The health impacts of exposure to wood smoke are diverse, and a substantial scientific and medical body of evidence points to short-term (acute) effects and longer-term (chronic) effects. Wood smoke is a cocktail of small, dangerous particles and droplets that easily work their way into our lungs, bloodstream, brain, and other organs.
Although children and the elderly are at higher risk, wood smoke affects everyone and its cumulative impacts on our health care systems are becoming more evident
Acute exposure to wood smoke triggers asthma attacks, allergic responses, heart attacks, and stroke. In pregnant women, wood smoke exposure is linked to a range of developmental responses in the fetus that lead to smaller lungs, impaired immune systems, and other abnormalities.
Chronic exposure is definitively linked to heart disease, a range of cancers, chronic obstructive pulmonary disease (COPD), and Type II diabetes.
Although children and the elderly are at higher risk, wood smoke affects everyone and its cumulative impacts on our health care systems are becoming more evident.
It is also known that people who heat their homes with wood burning appliances have higher indoor air pollution levels, and that they put neighbours in harm’s way from these emissions.
Even the cleanest wood burning stoves generate significantly more particulate matter than dozens of diesel trucks and cars combined. Due to their mass and aerodynamic properties, the particles of concerns in wood smoke tend to linger for hours or days at ground level, and atmospheric phenomena including inversions and low venting index days tend to hold these pollutants close to the ground in neighbourhoods where people live and work.
Wood smoke is made up of more than 200 chemicals. Many of these chemicals are significantly more toxic than the chemical mixture found in tobacco smoke. The smell associated with burning wood that many profess to enjoy is actually benzene – one of the most carcinogenic chemicals. Wood smoke also releases significant amounts of dioxins, furans, heavy metals, and other equally hazardous chemicals.
Burning wood to heat your home is problematic from an environmental perspective too. It is well established that black carbon released from biomass burning acts as a powerful short-lived climate changing pollutant. This soot is circulated in the atmosphere, absorbs and retains incoming heat from the Sun, and lands on glaciers thus accelerating their rate of melting and retreat.
Burning wood is not a carbon neutral source of energy either, and many new studies conclude that it is a disaster for climate change. Burning wood releases more carbon per unit of energy than burning coal. The burning of trees immediately puts decades’ worth of stored carbon into the atmosphere. This carbon would otherwise be locked into the soil where it plays an important ecological role in forests through processes of decomposition, nutrient cycling, and supporting new growth.
In communities where wood burning for residential heating is common, much of the wood used is trucked in from wood lots. The environmental footprint of this practice needs to be more fully understood. Additionally, importing wood from elsewhere does nothing to reduce the risk of forest fires in communities who use these products. In fact, the use of wood burning appliances actually increases fire risk through chimney fires, release of stray sparks, and the storage of large amounts of combustible material around homes.
There are currently many alternatives to wood for residential heating applications. A hierarchy based on impact, cost-effectiveness, and emergency preparedness is one way to think about these choices. For everyday heating, mini-split air source heat pumps are an excellent option. They are often three to four times more efficient than using electric baseboard heaters, and can work in colder climates with the correct choice of technology. They are also less expensive to operate than buying several cords of wood each year. Consider also the convenience of simply clicking a button to heat your home.
Efficient propane stoves and heaters are an excellent complement to heat pumps and can provide top-up heating on very cold days as well as backup heating during power outages. Wood stoves should only be used during extended power outages on cold winter days, and can be thought of as the equivalent of a standby generator.
As a rule of thumb, people should wait for at least three hours during a power outage before starting a fire. We would never dream of running a generator every day to power our homes, and similarly the use of a wood stove for daily heating should be reconsidered.
Regional and municipal governments have been reluctant to deal with these issues for a range of reasons. The vocal and sometimes vitriolic response by the wood burning industry and its customers often drowns out reasoned discussion, and many elected officials perceive this issue as unwinnable or perhaps a form of “political suicide.” Instead, passing the buck is common and local governments play a game of hot potato where neither wants to step in to protect people from a well-established health risk.
The British Columbia Ministry of Environment has been dancing around this issue for decades as well, and only offers to study the problem in more detail. Given that many of these government meteorologists can barely predict weather patterns with any accuracy, relying on them to protect our health from air pollution is sheer folly.
Perhaps we need a different approach and a different provincial lead on this topic. Since wood smoke is primarily a human health issue, and the air shed is shared by all, it makes sense that the British Columbia Ministry of Health become the natural home for wood smoke and other air pollution issues.
In general, municipal governments have shown that they are incapable of acting decisively and strongly to protect public health and the well-being of people in their communities.
Other actors have also played a decidedly obstructionist role in moving toward protection of the public interest on this issue. The B.C. Lung Association has been a strong advocate of wood stove exchange programs. Working with the hearth industry and the provincial government, the B.C. Lung Association has legitimized a flawed technology.
So-called “clean” EPA certified stoves are not the solution. These stoves never perform in the real world as well as laboratory tests indicate, emit more dioxins and furans due to their higher operating temperature, and begin to degrade in terms of performance very quickly. They also emit hundreds of times more pollution than using natural gas, propane, and other hydrocarbon-based home heating appliances.
Community groups are leading the charge on raising awareness of this issue. For far too long our local and provincial governments in British Columbia have ignored wood smoke and downplayed the significance of this risk issue. In many rural communities and in smaller cities, governments have dropped the ball for decades and refuse to adequately monitor air quality citing budgetary and personnel limitations. Concerned citizens have set-up an extensive and growing network of low-cost air quality monitors made by PurpleAir.
Kamloops currently has 15 of these WiFi-enabled, real-time particle sensors. Other communities in British Columbia with this technology include Parksville, Duncan, Courtenay, Lasqueti Island, Gabriola Island, Vancouver, Victoria, Prince George, and Kamloops. These monitors can be viewed at http://map.purpleair.org
To date, the monitors in Kamloops, Gabriola Island, Parksville, and Courtenay are showing a very distinct and troublesome pattern. Because of wood smoke, these communities have in some locations air pollution levels during winter months that far exceed levels seen in large cities like Victoria and Vancouver. Some of our sensor locations have regular readings that rival bad air days in China and India. A sensor located at Ord Road in Kamloops often displays these kinds of readings.
Wood smoke is creating hyper-local hot spots that expose people in the immediate neighbourhood to levels of air pollution not normally recorded by provincial air quality monitors. A “swarm” of distributed monitors using PurpleAir technology is revealing a deep and significant problem that was previously undetected.
Wood smoke, and the cultural and social practices that allow it to be generated without much regulation and control, operates in a vacuum where preconceptions, origin stories, and strong emotions impair action. We need another narrative. Dealing compassionately yet effectively with wood smoke is part of this transition to a green, clean, and healthy future.
Dr. Michael D. Mehta is a professor of geography and environmental studies at Thompson Rivers University who writes on behalf of Doctors and Scientists Against Wood Smoke Pollution, PurpleAir, Gabriola Island Clean Air Society, Families For Clean Air, Woodburnersmoke.net and the Thompson Rivers University ECO Club.