Carbon monoxide (CO) is a toxic, colorless, odorless, tasteless, and non-irritating gas. It is therefore undetectable to the person exposed to it. Because its density is similar to that of air, it spreads rapidly through the atmosphere, forming a mixture with air that is highly toxic to humans.

Carbon monoxide results from the incomplete combustion of carbon-containing materials (natural gas, wood, coal, butane, gasoline, fuel oil, petroleum, propane). This phenomenon is caused by:

• an insufficient amount of oxygen in the air (sealed room, inadequate ventilation, blocked air intake, etc.)

• the presence of impurities in the carbon-containing materials being burned

• insufficient exhaust of combustion gases (improperly connected flue, blocked or poorly swept chimney, etc.)

• prolonged or improper use of an appliance

• a malfunction of the appliance used for combustion.