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Air pollution



  1. Home
  2. Cancer information
  3. Reduce your risk
  4. Know your environment
  5. Air pollution

What is air pollution – and why is it dangerous?

Air pollution is a mixture of chemicals, particles and other materials in the air in amounts that could damage the environment or harm the health or comfort of humans, animals and plants.

If you already have lung disease or a heart problem, air pollution makes it worse. Air pollution has also been linked to certain cancers.

Outdoor air pollution

The air outside gets polluted in many ways. Sometimes the pollution comes from natural sources, such as forest fires and volcanoes. But more often, people create pollution through activities that send harmful substances into the air. These activities include:

  • running gasoline and diesel engines
  • generating power (such as smoke from coal-burning power plants)
  • industrial manufacturing
  • agricultural processes (such as managing soil or raising animals)
  • home heating and cooking
Air pollution coming from an industrial area

Air pollution in your community can be affected by:

  • some types of local businesses
  • local traffic patterns (vehicle type and how heavy traffic is)
  • whether you live in an urban or rural location
  • geography (valleys versus plains)
  • weather patterns (especially wind direction)
Air pollution coming from an industrial area

Indoor air pollution

Air inside your home can also be polluted. Major sources of indoor air pollution include:

  • second-hand smoke
  • radon from the ground
  • indoor burning of coal or wood
  • chemicals from paint or cleaning products
  • biological pollutants that come from living organisms (mould or dust mites)

Air pollution and cancer

Most types of air pollution are a mixture of many harmful substances, including small particles in the air, sulphur oxides, carbon monoxide, nitrogen oxides, volatile organic compounds (VOCs), benzene and polycyclic aromatic hydrocarbons (PAHs).

The International Agency for Research on Cancer (IARC) classifies types of air pollutants based on their link with cancer. For example, gasoline engine exhaust is classified as a possible carcinogen. Radon, diesel engine exhaust and outdoor air pollution are classified as known carcinogens.

IARC has also classified individual parts of air pollution as known carcinogens. These parts include:

  • particulate matter
  • some volatile organic compounds (such as benzene)
  • certain PAHs (such as benzo[a]purene)

Outdoor air pollution causes lung cancer

We know that smoking is the biggest risk factor for lung cancer in Canada. There is now strong evidence that outdoor air pollution also increases lung cancer risk. The more you’re around air pollution, the higher your risk of lung cancer will be. Researchers have also found that radon gas in indoor air can lead to lung cancer.

Research has also found a link between outdoor air pollution and a higher risk of bladder cancer. More research is needed to study the link between cancer and other parts of air pollution.

4 ways to reduce your exposure to air pollution – outside

Check daily air quality levels and air pollution forecasts in your area.
This information is usually provided with your weather forecast as the Air Quality Health Index. Follow the advice given with the forecast.
Try to plan strenuous outdoor activities at times when the air quality is best, especially if you’re sensitive to air pollution.
Avoid exercising near areas where traffic is heavy.
Lower how much you add to air pollution.
Use public transit, cycle or walk instead of driving. If you have to drive, don’t leave the engine running when you’re parked. And reduce the amount of heating and cooling in your home by making sure it is properly insulated.

7 ways to reduce your exposure to air pollution – indoors

Don't allow smoking in your house or vehicles.
Test your home for radon.
Buy a test kit or hire a certified radon professional to make sure the radon levels in your home are effectively reduced.
Make sure that appliances that run on or burn wood, coal, kerosene or gas are properly installed and ventilated, working properly, well maintained and inspected regularly.
Make sure your home is well ventilated.
Ventilation increases the amount of outdoor air that comes inside. It removes stale indoor air and reduces indoor air pollutants.
Switch from a coal- or wood-burning heat source to an electric, natural gas or oil heat source.
If you cook or heat with coal or wood, lower your risk by using efficient stoves and fireplaces with effective chimneys. Rather than high-temperature frying, use lower-temperature cooking methods (such as steaming, boiling, poaching, stewing, casseroling or braising).
Consider using an air cleaner, which removes particles from the air.
Unfortunately, most air cleaners are not very good at removing gases. That’s why controlling the source of indoor air pollution and having good ventilation are much better options for improving indoor air quality.
Don’t idle your vehicle or run other fuel-burning engines in a closed garage or workshop.