Where does carbon monoxide come from?

 It is a natural by-product of incomplete combustion.

Carbon Monoxide can be produced by gas or oil appliances like a furnace, clothes dryer, range, oven, water heater or space heater. When appliances and vents work properly, and there is enough fresh air in your home to allow complete combustion, the trace amounts of CO produced are typically not dangerous.

These conditions can cause CO levels to rise quickly:

  • Appliance malfunction, i.e. the heat exchanger on your furnace cracks.
  • Vent, flue, or chimney is blocked by debris or even snow.
  • Fireplace, wood burning stove or charcoal grill is not properly vented.
  • Vehicle is left running in an attached garage and CO seeps into the house.
  • Several appliances are running at the same time, competing for limited fresh air. This can cause incomplete combustion and produce CO, even if all appliances are in good working condition.