Discover how indoor air quality can be affected by outdoor air quality, building characteristics and activities happening indoors. Learn how to improve the air you breathe in your space.

Most people spend the majority of their time indoors. The quality of the indoor air we breathe can affect our health. Read the sections below to learn about some of the most common indoor air pollutants and review the actions you can take to improve indoor air quality in your home. For questions about indoor air quality at your workplace, please refer to WorkSafeBC.

  • Radon

    Radon is a possible silent threat in our homes

    Radon, an invisible and odorless gas, is a potential health hazard found in our homes. It enters the air during the natural decay of uranium present in some rocks and soils. When released outdoors, radon poses little health risks because it dilutes with outdoor air. However, within our homes, it can build up to dangerous levels.

    Understanding the risks

    Long-term exposure to radon is linked to lung cancer. In Canada, over 3,000 lung cancer deaths each year are attributed to radon exposure. Radon is the number one cause of lung cancer among non-smokers. People exposed to both tobacco smoke and radon have the highest risk of developing lung cancer. While a lifelong smoker carries a one in 10 risk of lung cancer, this risk increases to one in three when also exposed to high levels of radon. In contrast, a non-smoker's lifetime lung cancer risk at the same high radon level is one in 20.

    Protect yourself and your family

    To safeguard your loved ones, consider these tips:

    1. Test your home for radon:
      • Radon levels vary from one home to another, so it is crucial to test your home.
      • Radon testing is simple. Kits are available from sources like the BC Lung Foundation, online or by calling 1-800-665-LUNG (5864), Health Canada (Take Action On Radon) and from most home hardware stores.
      • Testing should span at least three months, including some winter months, for an accurate assessment.
      • Some libraries offer short-term radon detectors free of charge, providing a preliminary glimpse of radon concentrations. If elevated levels are found, conduct a long-term test for confirmation.
      • In the Fraser Health region, you can find short-term detector lending programs at Coquitlam and Fraser Valley Regional libraries and other libraries may also have similar programs.
      • Additional resources for radon testing are available for renters, through the BC Lung Foundation.
    2. Mitigate high radon levels:
      • Radon is measured in units of Becquerels per cubic metre (Bq/m3). Health Canada recommends that homes with levels above 200 Bq/m3 be mitigated.
      • Radon enters buildings through cracks and openings in walls and foundations that are in contact with radon-containing soil. Therefore, mitigation typically involves the installation of a system to vent radon from beneath the home to the outdoors.
      • Post-mitigation testing should be done to ensure radon levels have been lowered.
      • Mitigation should be done by a professional. You can find a qualified radon professional at Take Action On Radon.
      • The Canadian Lung Association offers a grant to help with radon mitigation.
    3. If you smoke, consider quitting:
      • Lung cancer risks are significantly higher for people who smoke cigarettes and are exposed to radon.
      • Connect with your primary care provider to discuss smoking cessation options. You can also access a free provincial program to help you quit or reduce smoking at
      • Find more support options at

    Find out more

    To learn more about radon and its risks, visit the following resources:

    • Radon Map: This resource from the BC Centre for Disease Control features a map showing radon risk by area in British Columbia. While no areas are entirely free of radon, some regions are at higher risk of elevated radon levels in homes and buildings. You'll also find comprehensive information on testing and mitigation.
    • Take Action on Radon: A national initiative, funded by Health Canada, to bring together radon stakeholders and raise awareness on radon across Canada.
  • Carbon monoxide

    Carbon monoxide: A silent household threat

    Carbon monoxide is an invisible, odourless and tasteless gas that can pose a serious danger in the home.

    It is produced whenever fuels such as natural gas, gasoline, oil and wood are burned. In homes, carbon monoxide can be released from malfunctioning or poorly vented fuel-burning appliances, such as furnaces and fireplaces. Using outdoor appliances like BBQs and camp stoves indoors during power outages can also increase carbon monoxide to dangerous levels.

    Understanding the risks

    Inhaling carbon monoxide can reduce the blood’s ability to carry oxygen, leading to carbon monoxide poisoning, a potentially life-threatening condition. Risk is higher in winter, when windows and doors tend to be closed and outdoor air vents are more likely to be blocked by debris, ice or snow, causing carbon monoxide concentrations to build up indoors.

    Carbon monoxide poisoning can also occur in summer when exhaust fumes from boats and vehicles, as well as use of camp stoves and portable fuel-burning appliances in enclosed spaces like tents, become significant sources of carbon monoxide.

    Know the signs and symptoms of carbon monoxide poisoning:

    • Dull headache
    • Weakness
    • Dizziness
    • Nausea or vomiting
    • Shortness of breath
    • Confusion
    • Blurred vision
    • Loss of consciousness

    If you suspect carbon monoxide poisoning, leave your home immediately and seek medical attention without delay.

    Protect yourself and your family

    Take action to prevent carbon monoxide exposure in your home:

    1. Install carbon monoxide detectors in your home. Because carbon monoxide is invisible, the only way to know if harmful levels are present is to install detectors. These detectors will sound an alarm if carbon monoxide concentrations reach dangerous levels. You can buy carbon monoxide detectors at most home hardware stores.
    2. Have your furnace and fireplace cleaned and inspected before each heating season.
    3. Only use fuel-burning space heaters in well-ventilated areas. Electrical space heaters pose no danger of CO poisoning, unlike those that burn fuels, such as kerosene.
    4. Do not start or leave vehicles running in a garage, even with the garage door open.
    5. When using a gas-powered generator for electricity, be sure to keep it a safe distance away from the home.
    6. Ensure heating vents are clear of snow, ice and debris.
    7. If your home loses power, do not use fuel-burning appliances meant for outdoors to warm your home or to cook. Instead, check with your local government to see if warming centres are available in your area.
    8. Do not use portable heaters or lanterns in enclosed areas, such as tents, campers and other vehicles. This is even more important at high altitudes, where the risk of carbon monoxide poisoning is increased.

    Learn more:

  • Mould


    Moulds are fungi naturally found both indoors and outdoors. Warm and moist conditions promote mould growth. Mould is often not dangerous; however, it can cause allergic reactions and illness in people with pre-existing conditions or weak immune systems. Some studies have found increases in common symptoms such as coughing, wheezing and headaches in people who live in homes with dampness and visible mould.

    See HealthLink BC’s page on preventing mould.

    Related resources

  • Asbestos

    Asbestos is a mineral used for its insulating properties. It is in certain vinyl floor tiles, soundproofing ceiling tiles, roof shingles, insulation, drywall and other materials. If inhaled, asbestos can cause cancer and other illnesses. You can be exposed to asbestos when a building is being renovated or demolished. You can also be exposed during car maintenance. Asbestos can cause cancer and other diseases. Always hire a professional to test for it if you are renovating or repairing a building.

    Related resources

  • Improving indoor air quality

    Actions you can take to improve your air quality at home

    • Get your home tested for radon (radon is low in most areas of the Fraser Health region, but some areas have higher levels).
    • Get a carbon monoxide alarm.
    • Use a hood fan when cooking and a fan when showering.
    • Do not leave cars idling in your garage.
    • Improve ventilation. You can do so by leaving indoor doors open, opening windows and keeping vents clear.
    • Repair water leaks right away.
    • See this Health Canada webpage for more information.
    • See the York Region Clean air at home guide.
  • Cooking and heating

    Poor indoor air quality from combustion

    When we burn any fuel, such as wood, natural gas, propane, kerosene, charcoal or tobacco, it can make pollutants and particles that are harmful to our health.

    We do not always think of the pollutants that are created when we cook or heat our homes, but wood stoves and gas appliances can create indoor air pollution. Natural gas and propane can also release carbon monoxide and other harmful chemicals into the air which can harm people and pets.

    The best ways to improve air quality are to control sources and have proper ventilation.

    To control sources:

    • Follow the manufacturers’ instructions for all combustion appliances.
    • Regularly service and clean appliances and vents such as chimneys.
    • Use only fuels recommended for each appliance.
    • Make sure that wood stoves are installed and maintained correctly. Doors should be tight fitting to prevent leakage.
    • Use only aged or dried wood, not pressure treated or painted wood that may form more toxic compounds when burned.
    • Inspect furnace and flues, and repair cracks and damaged parts. Open the flue when using your fireplace. Do not let a fire within a wood heater smolder, especially just before opening the firebox.
    • Change your furnace and air conditioning filters every couple of months if using them often. Consider using a more effective furnace filter.
    • Never allow smoking in or near the home.
    • When you are cooking, cook on the back burners where possible.

    Improve ventilation

    • Use a stove hood and fan that vents outside when cooking with gas stoves and ranges.
    • When you need to replace a space heater, buy a vented heater.
    • Make sure enough fresh air gets into your home from the outdoors, especially when using combustion appliances.
    • Make sure fresh air intake vents are not blocked or covered.
    • Do not have air intake vents coming into your home from your garage. Never idle a vehicle in an attached garage.

    More information is available from


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