Photo: The air we breathe

Air pollution is a significant environmental health problem. (Credit: trotskyite via Flickr.)

It's free, it's all around us and we can't live without it for more than a few minutes. But we often take the air we breathe for granted.

Air pollution is an umbrella term for airborne chemicals, particulate matter and biological materials that have a negative impact on human health, the environment and the economy. The subset of air pollutants that cause smog and acid rain (sometimes referred to as Criteria Air Contaminants or CACs) include:

  • Carbon monoxide (CO);
  • Nitrogen oxides (NOx);
  • Sulphur oxides (SOx);
  • Particulate matter (PM);
  • Volatile organic compounds (VOCs); and
  • Ground-level ozone (O3) — a secondary pollutant formed when NOx and VOCs react.

According to the most recent environmental indicators, 5.5 per cent of cardiopulmonary (heart and lung disease related) deaths can be attributed to ground-level ozone exposure, which has increased over the past decade. During the same period, exposure to fine particulate matter has remained unchanged (i.e., did not improve) and accounts for three per cent of cardiopulmonary deaths. The Canadian Medical Association estimates that Canada's air pollution is responsible for 21,000 premature deaths, 92,000 emergency-room visits and 620,000 visits to a doctor's office in a year, and that the economic cost of air pollution-related illness and death in Canada tops $8 billion a year.

Smog is a persistent problem in many places and takes a toll on the health of Canadians. The U.S. has recently updated critical air quality standards, but Canada's National Ambient Air Quality Objectives date back to the 1970s.

Where does it come from?

Criteria air contaminants share a number of common sources, notably the combustion of fossil fuels. These sources are also the leading contributors of greenhouse gases that cause climate change, so taking action on air pollution is win-win. Some common sources include:

Industrial emissions

About half of Canadian air pollution is produced by large industry, including industrial combustion systems. Industrial emissions from the United States also contribute to smog and acid rain in some parts of Canada. Ontario estimates that half of the air pollution in the province blows in from the U.S.

Coal and gas-fired power plants

Electricity generation from fossil fuels is responsible for a large share of Canadian carbon monoxide, nitrogen oxides, sulphur dioxide and fine particulate matter emissions. Electricity generation is also a significant source of mercury emissions. Mercury is a toxic heavy metal that can harm the brain.

Vehicle emissions

Transportation is one of the largest sources of air pollution in Canada. This is of particular concern in dense urban areas with many vehicles on the road and high traffic congestion.

Burning wood for heating or for waste disposal

This is a significant source of particulate matter pollution in parts of Canada. For example, in British Columbia, residential wood heating accounts for approximately 15 per cent of total PM emissions. In Quebec, it is the leading source of fine particulate emissions associated with human activity, at 47%. In addition, burning wood can release other toxic substances into the air if the wood has been treated with chemicals, glue or paint. Inefficient wood stoves and fireplaces can seriously compromise air quality inside homes, as well as contribute to outdoor air pollution problems. Even cleaner-burning wood stoves emit fine particles into the air.

How to protect yourself from air pollution

  1. Watch out for local air quality advisories. Environment Canada has developed an Air Quality Health Index to alert the public during times of high exposure to ozone, particulate matter and nitrogen dioxide. The AQHI offers advice for limiting physical and outdoor activity when local air quality is deteriorated.
  2. Burn wise — or don't burn at all. If you burn wood for home heating, opt for a more efficient woodstove or a pellet stove. A non-certified woodstove can emit as much fine particlulate pollution in nine hours as a car does in a year (driving 18,000 km). Check for a Canadian Standards Association or U.S. EPA certification label on the back of the appliance. Never burn garbage, painted or treated wood, plywood, particle board, or wet or rotten wood, which can emit harmful chemicals and fine particles. Use alternatives to burn barrels for waste disposal. Older adults, children and people with heart or lung diseases should be particularly careful to limit their exposure to smoke and other sources of air pollution.
  3. Take alternative transportation, conserve energy. Making less pollution is one of the best ways to reduce exposure to its effects.
  4. Swap your old gas-powered mower for an electric or push model. Mowers with two-stroke gas engines can emit as much smog-forming pollution in one hour as driving a car more than 320 kilometres!

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