I particularly like the comparison between CO and Natural gas, and the claim that CO has an odour :-
WHAT IS CO ? - THE FACTS !! CO is not Well Understood: Misconceptions: Properties, Presence & Detection:
CO is easy to detect.
CO is lighter than air and therefore rises (to the ceiling) and stays there.
CO is not combustible.
CO and natural gas are the same thing.
You can always tell if CO is present because of a peculiar odour that will be present.
A brand new, well designed, perfectly "tuned" heating/cooking device cannot produce toxic/lethal amounts of CO.
Diesel engine exhaust never contains adequate CO to cause harm.
HVAC and gas company personnel always check for CO when performing maintenance/service on home heating systems.
CO will be detected immediately by service personnel if it is present in a home heating system.
When your home CO detector shows low levels of CO, it is probably just an instrument malfunction.
Cracks in heat exchangers are responsible for production of CO.
Home CO detectors/sensors are the best devices to ferret out CO because they react to very low levels of the gas.