Exhaled carbon monoxide level as an indicator of cigarette consumption in a workplace cessation program in Taiwan

J Formos Med Assoc. 2006 Mar;105(3):210-3. doi: 10.1016/S0929-6646(09)60307-7.


Background: Smoking cessation programs are critical to the safety and health of workers. Exhaled carbon monoxide (CO) is an effective indicator of smoking in clinics and hospitals. Its application in the community and workplace, however, remains limited. This study assessed whether exhaled CO concentration can be used as an objective indicator of the amount of daily cigarette consumption among smokers in the workplace in Taiwan.

Methods: A total of 150 workers from a chemical manufacturer in Taiwan were included; there were 27 nonsmokers and 123 current smokers. The number of cigarettes smoked daily by each subject was reported, and exhaled CO concentration was measured in each subject using the Micro CO meter (Micro Medical Ltd, Chatham, Kent, UK).

Results: Exhaled CO levels were associated with the number of cigarettes consumed daily, with a correlation coefficient of 0.73 (p < 0.01) and an adjusted R-square (simple linear regression model) of 0.44. The mean exhaled CO level of nonsmokers was 4.2 ppm (95% confidence interval, 3.3-5.1). A reading of > 6 ppm had a sensitivity of 84% and specificity of 85% in detecting workplace smoking.

Conclusion: Exhaled CO level can be used as an objective, noninvasive indicator to determine the smoking status of an individual in the workplace.

MeSH terms

  • Adult
  • Breath Tests*
  • Carbon Monoxide / analysis*
  • Feasibility Studies
  • Humans
  • Male
  • Occupational Health Services*
  • Smoking / epidemiology
  • Smoking Cessation*
  • Taiwan


  • Carbon Monoxide