Carbon Dioxide is a gas that is both colourless and odourless. Not only is CO2 produced naturally in the environment, but it can also be created. CO2 can be created through human activities like burning gasoline, oil, coal, and wood. Respiration increases the level of CO2 in air as an individual exhales.

Comfort

The measure of carbon dioxide in a room signifies the amount of fresh air available. Common complaints, due to uncomfortable levels of carbon dioxide, include headaches, an increasing pulse rate, particularly high fatigue, and breathing difficulties. In extreme cases, high levels of carbon dioxide can induce heavy nausea, dizziness, vomiting, and even loss of consciousness. However, this is unlikely in most residential buildings.

Note: The included diagram to the right illustrates how Carbon Dioxide concentration levels have increased over the last 50 years. 

Residential

• Most homes contain carbon dioxide ranging from 300 to 1,000 ppm depending on numerous factors such as how many people are occupying an area, ventilation, internal vegetation, and much more.
• Since CO2 is heavier than other gases found in air it tends to sink, thus high amounts of CO2 can be found in basements.
• Children take in more air per unit body weight at a given level of exertion than adults which is why high levels of CO2 can affect children more significantly.

Commercial

• The EPA reported that the air found within office buildings can be up to 100 times more polluted than the outside air.
• Having plants around a building can help maintain and lower levels of carbon dioxide because they absorb it during photosynthesis to make sugars. These plants will then release much needed oxygen back into the air, promoting good indoor air quality.

Clean Rooms

• ASHRAE has identified carbon dioxide as the only measurable variable in hospitals concerning acceptable indoor air quality.