Carbon dioxide, also called carbonic acid gas, is a naturally occurring colourless, odorless, incombustible gas formed during respiration, combustion, decomposition of organic substances, and the reaction of acids with carbonates. It is present in the Earth’s atmosphere at low concentrations and acts as a greenhouse gas. (Government of Canada, 2015. Toxic substances list: carbon dioxide https://www.canada.ca/en/environment-climate-change/services/management-toxic-substances/list-canadian-environmental-protection-act/carbon-dioxide.html)
