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Pollution & air quality

Outdoor air quality

Heating methods and open burning

We all want our homes and workplaces to stay warm and comfortable throughout the cold winter months. But staying comfortable also means enjoying good air quality- and unfortunately some heating sources can seriously pollute the air. Certain heating methods can cause enough pollution, indoors and out, to make people feel sick. People who have asthma, COPD, and other lung disease are especially at risk.

If you know more about the health effects of many heating methods, you can make a better decision about how to heat your home or workplace.

Home heating options

Because certain energy and heating options can pollute the air and make people sick, it's important to consider many factors when choosing how you'll heat your home. Here are some things to consider:


The cost of different options will vary from region to region depending on supply and demand. Natural Resource Canada provides a useful calculator for determining which energy source is the most cost effective.

Health effects:

Certain methods of heating can trigger breathing problems, especailly in people with lung diseases like asthma or COPD:

  • Forced air heating systems: Forced air heating systems can blow dust, other allergens, and irritants into the air. This can't be totally fixed but you can reduce it by cleaning your vents regularly. Your vents are the grill-like pieces that are removable. To clean them, remove the vent and vaccum it all over or wipe it down with a clean wet cloth. If, while you're cleaning your vents, you notice some dirt in the nearby ducts, you can vaccum this out too. In general, we do not encourage people to get their heating ducts professionally cleaned.
  • Wood stoves: Wood stoves pollute indoor and outdoor air- read more about the health effects of wood burning, below. Newer high-efficiency CSA/EPA B415- certified wood stoves release less pollution, but people who are sensitive should choose another heating options. (CSA/EPA B415- certified wood stoves are models that meet certain emissions standards set by the Canadian Standards Association and the U.S. Environmental Protection Agency.)
  • Propane and natural gas stoves/fireplaces: Propane and natural gas stoves or fireplaces can increase the level of carbon monoxide in the building. High levels of carbon monoxide can cause sickness and death. If you live or work in a building with a propane- or natural gas-powered fireplace or stove, you should install a carbon monoxide detector.
Environmental effects:

The burning of fossil fuels such as coal, oil, natural gas, or propane (a refined component of oil or natural gas) as well as biomass sources such as wood, all release chemicals into the air. These chemicals include sulphur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds (VOCS), particulate matter (PM), carbon monoxide (CO) and other toxic material. These pollutants can have direct effects on respiratory and cardiovascular health, and some of them cause acid rain or ground-level ozone, a principal component of smog. As well, these materials release carbon dioxide (CO2) which is a greenhouse gas and contributes to climate change. Generally speaking, with respect to fossil fuels and the release of pollutants, coal releases the most pollutants and natural gas is the cleanest choice.

Extraction, refining, transportation and end-use combustion of fossil fuels all affect the environment. End-use combustion can occur either at the home, if the household uses furnace oil, or at an electric power generation site using oil to create electricity. Using oil for heating a home is better for the environment than using electricity made from oil at a power plant because the extra conversion step decreases the overall end-use energy per volume of oil. For example, electric heat produced from a conventional thermal power plant using oil has a total efficiency of about 30% by the time the electricity is used in the home or business. Electricity from a combined cycle natural gas plant has an end-use efficiency of about 45%. The end-use efficiency of oil or gas used in a high efficiency furnace in the home is at least 75%.

Electricity is also generated from nuclear power and hydroelectric sources. Hydroelectric projects are expensive to build but have low operating costs, and longer life spans than coal or nuclear plants. They use a renewable resource, emit no air pollution or greenhouse gases but significantly impact natural ecosystems and man-made landscapes during construction. Nuclear power is dependent on the very concentrated energy in uranium. Nuclear power stations are expensive to build and it has been estimated that nuclear generated electricity is more expensive than major alternatives such as hydro and coal. Nuclear reactors produce no greenhouse gases and the entire fuel cycle produces about one-sixth as much CO2 per unit of electricity as does the use of coal. The challenge of this technology is the safe storage of nuclear waste and the threat (albeit statistically small) of unintended release of radioactive material.

Commonly used heating and energy sources:

Almost all homes and businesses use electricity to run appliances, lights, etc. and many use electricity for heating/cooling their buildings. Other common heating sources include furnace oil, natural gas, propane and wood. When comparing the efficiency of these different options while they are being used in the home or office (not taking into account the efficiency losses involved before delivery to the end-use site), electricity is 100% efficient because there is no conversion from when the electricity enters the building to its use to power lights and appliances. There are efficiency losses at the appliance level (when electricity is converted to light or to heat) and this is proportional to the efficiency of the appliance. Oil, propane and natural gas have similar efficiencies when used to produce heat. Their efficiencies range from 60% to 96% depending on the efficiency of the burner or furnace. Wood has an efficiency range of 45%, when used in a central furnace, to 80%, when used in a pellet stove..

Emerging, environmentally friendly, heating and energy options:

Increasing concern for the environment and the health effects of combustion of fossil fuels has increased the use of cleaner, renewable sources of energy. These include solar and wind power and the use of geothermal energy such as ground-source heat pumps.

What you can do:
  • If you are building or renovating, choose a power/heating system that has a low impact on the environment and which has the highest efficiency rating.
  • Conserve energy in all aspects of your life by turning down your thermostat, using appliances and hot water only when essential, insulating your house, and using natural sun and shade to help heat and cool your house.
  • Consult green building websites and other sources of information for many ideas on building and renovating your home or business to reduce energy use.
Heating with wood - what you need to know

Approximately three million Canadian households use wood to heat their homes. Burning wood can release pollutants into the air we breathe, especially when poor burning techniques and wood burning appliances are used.

Research indicates that a reduction in disease resistance is associated with wood smoke exposure. Wood smoke exposure can disrupt the cellular membranes, depress immune system activity, damage the layer of cells that protect and cleanse the airways, and disrupt enzyme levels. The health effects of wood smoke exposure include increased respiratory symptoms, increased hospital admissions for lower respiratory infections, exacerbation of asthma, and decreased breathing ability. Young children, the elderly, and people with pre-existing cardiopulmonary disease are most likely to be affected, however the harmful pollutants associated with wood smoke also directly impact on the health of otherwise healthy people.

What's in wood smoke?

Environment Canada and Health Canada have identified many hazardous chemical substances in wood smoke, including:

  • PM10 (inhalable particulate matter less than 10 microns in diameter) - PM10, which consists of a mixture of microscopic particles of varied size and composition, has been declared a toxic substance under the Environmental Protection Act. These particles can be inhaled deep into the lungs, leading to serious respiratory problems, including excess mortality, especially among those with pre-existing cardiopulmonary illness.
  • Carbon Monoxide (CO) - can reduce the blood's ability to supply necessary oxygen to the body's tissues, which can cause stress to the heart. When inhaled at higher levels, CO may cause fatigue, headaches, dizziness, nausea, confusion and disorientation and, at very high levels, lead to unconsciousness and death. Fire Prevention Canada advises that CO detectors be installed in every home that has a combustion appliance or an attached garage.
  • Oxides of Nitrogen (NOx) - can lower the resistance to lung infections. In particular, nitrogen dioxide can cause shortness of breath and irritate the upper airways, especially in people with lung diseases such as emphysema and asthma.
  • Hydrocarbons (HC) - can damage the lungs.
  • Volatile organic compounds (VOCs) - can cause respiratory irritation and illness. Some VOCs emitted by wood-burning appliances, such as benzene, are known to be carcinogenic.
  • Formaldehyde - can cause coughing, headaches and eye irritation and act as a trigger for people with asthma.
  • Polycyclic aromatic hydrocarbons (PAHs) - Prolonged exposure to PAH's is believed to pose a cancer risk.
  • Dioxins and furans- Some dioxins and furans are carcinogenic.
  • Acrolein - can cause eye and respiratory tract irritation.
If you must heat with wood, follow these precautions

There are many things you can do to reduce the amount of pollution created by residential wood burning, and to improve the safety and efficiency of your wood burning appliance:

  • Burn small, hot fires - they produce much less smoke than ones that are left to smoulder.
  • Burn seasoned hardwood - burning "green" or wet wood produces significantly more smoke. Soft woods like pine produce more emissions and deposits inside your chimney. Firewood should be seasoned for at least six months.
  • Split wood into pieces that are 10-15cm (4-6in) in diameter. Fires burn better with more surface area exposed to the flame.
  • Never burn garbage, plastics, cardboard or Styrofoam. Burning garbage releases poisons
  • Never burn wood that has been taken from salt water. Chlorine combines with the smoke to produce dioxins and furans, which are dangerous carcinogens.
  • Burning treated or painted wood, particleboard or plywood represents a health hazard. Wood treated with varnishes and sealants, wood from orchards sprayed with pesticides and pressure-treated wood may contain toxic chemicals. Burning treated wood may release these toxic chemicals into the environment in the smoke or in the ash that is disposed of later.
  • Store wood outside, off the ground and covered. Bring it into your home as needed. The excess moisture found in green wood increases the relative humidity of the indoor air, which can lead to mold and mildew growth. Both can cause severe allergic reactions and asthma attacks.
  • Use a high-efficiency wood stove, fireplace or insert that is certified as low emission by the EPA, as standard accepted in Canada. These wood burning appliances burn most of the smoke right in the firebox and can cut emissions by up to 90 percent. High-efficiency units allow you to burn a third less wood and get the same amount of heat.
  • Reduce your heating needs by making your house more energy efficient.
  • Regardless of the type of wood-burning appliance, it should be installed by professionals and inspected and cleaned at least once a year by a technician certified under the Wood Energy Technical Training (WETT) Program or, in Quebec, the Association des professionnels du chauffage (APC). These certified installers and chimney sweeps have gone through a rigorous training program that is recognized by the industry and by government.
Municipal bylaws regulating wood heating

Many municipalities experience air quality problems because of residential wood combustion. For municipalities who'd like to develop regulations on wood burning, Environment Canada has developed a Model Municipal By-Law for Regulating Wood Heating Appliances (PDF).

For more information on wood heating, see the Burn It Smart website from Natural Resources Canada.

Open burning

Open burning creates smoke that contains many pollutants which can cause health problems and reduce visibility. Smoke from open burning hurts the health Canadian in both urban and rural areas.

Open burning is the burning of organic material to dispose of gardening, agricultural, and land development debris; to remove residue and slash in the forestry industry; to dispose of sawmill waste; to prevent wildfires; to clear grazing range; and for recreational uses.

How open burning hurts human health

There are some situations where open burning may be necessary - such as controlled burning by professionals to prevent forest fires. Unfortunately, smoke produced is a major source of air pollution and directly affects our quality of life. Smoke is a complex mixture of gases and microscopic particles that is an irritant to eyes and airways, and may cause or aggravate respiratory illness and heart disease. In some rare cases, breathing smoke can cause death.

Smoke from an open fire can seriously pollute your neighbourhood. This is especially true when burning takes place on calm days with no wind. The particles and gases produced can build to levels that are harmful for days. A haze may cover whole communities and reduce visibility. Calm days are often the times that people choose for open burns, because they are concerned about forest fires and do not want to blow smoke into their neighbours' yards.

Closing doors and windows will not help. Smoke can easily waft through small cracks and holes, resulting in polluting your indoor air as well as the outdoor air.

Symptoms caused by open burning

Even smoke from leaf burning can irritate the eyes, nose and throats of healthy adults. Smoke from open burning can be much more harmful to small children, the elderly, and people with lung problems such as asthma or chronic obstructive pulmonary disease (COPD). This is because the visible smoke from leaf fires is made up almost entirely of tiny particles that can reach deep into lung tissue and cause symptoms such as coughing, wheezing, chest pain and shortness of breath. These symptoms may not occur until several days after exposure to large amounts of leaf smoke.

What's in smoke form open burning?

Besides being an irritant, smoke contains many hazardous chemicals potentially harmful to human health. These include:

  • Acrolein is an alcohol aldehyde that smells bad, and irritates eyes and airways.
  • Formaldehyde is a preservative and a carcinogen, and can cause headaches and airway irritation.
  • Carbon monoxide
  • Nitrous oxides are gases that make it difficult to breathe and trigger asthma attacks.
  • Particulate matter are microscopic particles that can be breathed deep into the lungs
  • Polycyclic aromatic hydrocarbons (PAH's)
  • Volatile organic compounds (VOCs)
  • Dioxins can cause a variety of health problems. Dioxin exposure has been linked to: increased risk of cancer, developmental problems in children, heart disease, diabetes and harm to the immune system.
What you can do about open burning
  • Don't burn if you don't have to. Many urban areas have by-laws banning open burning.
  • Instead of burning debris, start a compost pile in your backyard for organic materials.
  • Reduce, reuse, and recycle products whenever possible.
  • Clean up wood debris by using a chipper to make mulch or decorative chips. If you heat with wood, you should only use wood that has been properly dried and seasoned.
  • Sawmill waste does not need to be burned at all. This residue can be recycled as chips for pulp and fiberboard, and compost and mulch.
  • Support efforts to reduce smoke pollution. Spread the news! Tell your friends, family, and neighbours how they can improve air quality.
If you must burn:
  • Follow the open burning rules that apply to your community and/or your industry. Contact your local fire services and/or Department of Environment for information on burning regulations.
  • Be aware of temperature inversions when smoke won't dissipate. (*Temperature inversions occur when the air near the surface of the earth is cooler than the air above, trapping air pollutants close to the ground and allowing them to build up.)
  • Be aware of "no-burn" periods.
  • Never burn toxic materials, such as plastics, tires, construction and demolition waste, treated and painted wood, and rubber. Find out where you can recycle these products or dispose of them safely.
  • Make sure that any debris that you burn from gardening, agriculture, and land development is only organic material (e.g. leaves, grass clippings, branches and weeds). Make sure the debris is dry. Wet and damp materials create more smoke.
  • For prescribed burning, the size of such a burn can be limited. It should never be allowed to smoulder or to include non-organic materials.
What about chimineas?

Chimineas are ceramic wood burning appliances that people use outdoors, often on patios. The same concerns apply here as to other open burning. The open design of these devices leads to inefficient burning of the wood. Wood smoke from chimineas may stay closer to the ground since they have low chimney stacks, and can pose a problem for neighbours.

Burning unwanted crop residue (Stubble burning)

Stubble burning is the practice of burning the residue of a crop rather than bailing it for livestock use or working it back into the soil. It has been a part of agricultural practice for many years. Crop residue refers to the straw, stubble and chaff from any agricultural crop following harvest. The remains of unharvested crop can be included.

The problem with stubble burning

Although it has been part of agriculture for many years, it is a practice used only by a small percentage of farmers. According to Agriculture Canada crop residue burning is not good farming practice because crop residue:

  • Helps prevent soil erosion
  • Absorbs the energy of raindrops
  • Binds soil particles and improves soil structure
  • Protects long term viability of the soil

In spite of its effect on agricultural land, this practice has continued as a matter of convenience and because some products, notably flax and canary straw are slow to break down and thus difficult to incorporate back into the soil.

The issue is not just soil management, it impacts on greenhouse gas emissions, safety risks and fire management, reduced visibility on roads, respiratory health impact and on waste management.

Health effects of stubble burning

The crop residue smoke, that is produced, is a health issue for all persons downwind of this activity. We must be aware of both the environmental and the human health effects when crop residues are burned. All burning creates harmful by-products, resulting in air pollution. It matters not whether oil, gas, wood or stubble is burned, there will be combustion products formed. The difference will be the amount of particles and gases formed. Oil and gas, for example burn much more cleanly and more closely achieve complete combustion, stubble burning is a dirty procedure that produces large amounts of fine particles that can be carried for long distances suspended in the wind.

Studies have indicated that short-term exposure to low-level increases in particles in the air is associated with an increase in illness and death, particularly in individuals with heart and lung conditions. Hospital emergency wards see an increase in asthma admissions during the burning season. People with lung diseases, such as asthma and chronic obstructive pulmonary disease (COPD) are more quickly affected by these tiny particles entering their breathing system. Children and the elderly are particularly sensitive.

Symptoms that can come from stubble burning:
  • More cases of lung disease
  • Coughing and shortness of breath; decreased lung function
  • Increase in emergency department visits
  • For people with allergies: sore eyes, sore throat, coughing, and nasal and sinus congestion.
  • In people with lung disease: need more medication, shortness of breath, sick enough to miss school and work. For people with lung diseases, one day of breathing crop residue smoke can mean one week of feeling sick.
Alternatives to stubble burning
  • Return crop residue into the soil using cropping devices and harrowing
  • Bale straw for livestock use.
  • Sell excess straw for industrial use such as straw particle board, ethanol production, etc.
If you must burn
  • Never burn at night. Damp conditions produce more harmful smoke emissions. Temperature changes and calmer conditions often cause smoke retention or poor dispersal. Burn only between 11:00 a.m. and sunset.
  • Have adequate fireguard and water supply.
  • Burn only when wind conditions allow for quick upward dispersion of smoke. It is imperative that Environment Canada be consulted regarding wind conditions in your area. Smoke should never be allowed to drift over neighboring communities or roads.
  • Do not burn across an entire field. A large field, stubble or windrow burn produces more smoke. Piled or baled straw will burn hotter and faster and produce fewer pollutants.
What you can do about stubble burning

Contact your Public health office and provincial agriculture representative and ask:

  • What legislation is in place to protect their health with respect to crop residue burning
  • If enforcement legislation to prohibit indiscriminate burning of crop residues is used.
  • If the province is actively discouraging these practices through education and assistance.
  • What farming groups are doing to discourage their members burning practices allowing controlled burning when weather conditions are ideal and impacts extremely low.
  • If there is research methods of utilizing crop residues for industrial purposes.

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