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Assessment of Tobacco Use
The best way of determining smoking status is to ask people: “Do you smoke?”
The exhaled carbon monoxide (CO) test detects exposure to CO in the last 12-18 hours. This can be used to assess smoking status AFTER a quit attempt and used prior to a quit attempt as a motivational tool. Higher levels (parts per million) equate with greater inhalation of tobacco smoke assuming the cause is tobacco smoking. It must be noted that the exhaled CO test indicates recent exposure to CO and will not indicate smokeless tobacco use and is not a measure of dependency. In pregnancy, a CO of 3 ppm has been proposed as an appropriate cut-off for referral to stop smoking services.
The cotinine test is more specific for nicotine exposure and ay be useful in the context of infrequent waterpipe use or smokeless tobacco use and can also be collected via a urine sample in the case of children who may be exposed to environmental tobacco smoke. It is not useful for people who use NRT or e-cigarettes and is a laboratory-based test.
Pack years provides a measure of exposure; this calculator also allows the evaluation of cigars, roll-up cigarettes, pipes, tobacco by weight and water pipe use and converts them to pack-year equivalents).
Number of years a person has smoked.
Clinical resource or information
PCRS Produced / Collaboration
Tobacco smoking and nicotine