carbon monoxide monitoring in smoking cessation

Last reviewed 02/2023

  • biochemical measures are generally used in smoking cessation studies rather than in routine clinical practice
  • one of the available biochemical measures is exhaled carbon monoxide. Measurements are not specific to cigarettes and half-life is short (3 to 5 hours).
    • levels fall to normal in 24 hours

Exhaled carbon monoxide in nonsmokers and smokers

Exhaled carbon monoxide (ppm) Exhaled carbon monoxide (ppm)
Nonsmoker 0-6
Light 7-10
Moderate 10-20
Heavy > 20

Another biochemical marker of smoking is cotinine, the primary metabolite of nicotine, which can be detected in serum, saliva, and urine

  • it has a long half-life (16 hours) and can detect smoking in the preceding 3 to 4 days, but requires laboratory analysis
  • cotinine will generate a false-positive test result in patients using nicotine replacement

Reference:

  • 1.Brunnhuber K et al. Putting evidence into practice: Smoking cessation. BMJ Group (Summer 2007).