Carbon dioxide in your home

Carbon dioxide (CO2) is an odourless, colourless and non-flammable gas. Learn about sources of CO2, its health effects and how to lower exposure to CO2 in your home.

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Sources of CO2 in indoor air

Carbon dioxide is a pollutant found in indoor and outdoor air.

Indoors, CO2 is mainly produced through the respiration (breathing) of occupants, but can also come from:

The level of CO2 in indoor air depends on 3 main factors:

The amount of indoor CO2 is often used:

Outdoors, CO2 comes mainly from:

Health effects of CO2

As CO2 increases, you may be at increased risk of:

These effects may not be from CO2 exposure, but from poor indoor air quality in general.

How to lower exposure to CO2 in your home

You can lower levels of CO2 indoors by increasing ventilation and controlling the sources of CO2.
You can increase ventilation by:

You can control indoor sources of CO2 by:

Exposure limit for CO2 in indoor air in Canada

We developed an exposure limit for CO2 in Canadian homes based on:

The long-term exposure limit is 1800 µg/m3 or 1000 parts per million (ppm) based on a 24-hour average. This exposure limit:

This limit protects the health of Canadians including vulnerable populations such as:

The recommended exposure limit allows public health officials and other professionals to assess the risk from indoor air pollutants.

CO2 values in other countries

Canada's long-term exposure limit (1000 ppm) is in line with standards from other countries and organizations.

Countries with established standards or guidelines for CO2 of 600 to 1000 ppm include:

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends maintaining indoor CO2 levels no greater than 700 ppm above ambient levels (assumed to range between 300 and 500 ppm).

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