Carbon Monoxide Monitoring

Carbon monoxide (CO) is an odourless, tasteless and poisonous gas which is present in tobacco smoke. Carbon monoxide reduces efficiency in breathing and makes blood more sticky, increasing risk of coronary heart disease (CHD) and other circulation problems.

The carbon monoxide in end expired breath is measured in particles per million (ppm). 6ppm corresponds to approximately 1% carboxyhaemoglobin (COHb), and the CO levels reflect the amount of smoke inhaled. This is a more accurate indicator of smoke intake than number of cigarettes per day. The following affect CO levels and need to be taken into consideration when interpreting a reading:

  • Number of cigarettes smoked so far today
  • Time since last cigarette
  • Time of day (CO levels rise during the smoking day and decline overnight)

The good news:

  • CO levels will return to non-smoking levels after about 24 hours of not smoking
  • This improvement is permanent unless further smoking occurs
  • This can increase motivation to stop, and reinforce abstinence

What can affect an accurate reading:

  • Unusually high ambient CO concentrations due to weather conditions or air pollution (do not recalibrate the monitor, just record the ambient and the therapist’s reading)
  • Levels above the cut-off point in genuine abstainers due to faulty heating, car exhaust leaks or (rarely) lactose intolerance (some monitors confuse CO with hydrogen)

If you need to loan a CO monitor from us, please download the  CO Monitor  Loan Form 2015.doc and we'll be in touch.

You may also find the following downloads useful:

Infection Control and Maintenance Guidelines
PiCO+ Operating Manual
Smokerlyzer Catalogue
Carbon Monoxide Chart.pdf

Design: Postscript