CO is a product of incomplete combustion. Any fuel-burning device has the potential to produce dangerous levels of CO gas. Examples of common devices that may emit CO include:

• Fuel-fired furnaces (not electric)
• Gas water heaters
• Fireplaces and wood stoves
• Gas stoves
• Non-electric space heaters
• Gas dryers
• Charcoal grills
• Lawnmowers, snowblowers, etc.
• Automobiles
• Gas powered generators