How long does CO last in the body?

How long does Carbon Monoxide (CO) stay in the body?

CO is eliminated through the lungs and has a half-life of approximately 4 hours(1). Therefore you must not leave it too much longer than 20-30 minutes after having a cigarette to take a CO reading as it leaves the body relatively quickly. A smoker can blow non-smoker readings approximately 24 hours from going ‘cold turkey’ and quitting smoking completely.

If the problem persists or has not been resolved by the information provided above, please contact Bedfont or your local distributor for more advice.


1. Andrew H. Carbon Monoxide ‘The Silent Killer’ Feasibility Study 2009/2010. 1st ed. London: London Ambulance; 2017