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piCO
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Operating Manual
English
Frequently Asked Questions (FAQ)
Frequently asked questions about breath carbon monoxide (CO) monitoring in smoking
cessation:
Q What is carbon monoxide?
A
Carbon monoxide (CO) is a poisonous
gas that you cannot smell or see. When
smoke is inhaled from a cigarette, CO is
absorbed into the blood through the lungs.
CO is dangerous because it binds with
haemoglobin in the red blood cells about
200 times more readily than oxygen,
depriving the body of vital oxygen.
Q What does a breath CO test show?
A
It shows the amount of carbon monoxide
in a person’s breath (ppm CO), which is
a measure of blood carboxyhaemoglobin
(%COHb). It acts as an indicator of
the possible level of some 4,000 toxic
substances in cigarette smoke, 60 of
which can cause cancer.
Q What does ppm and COHb mean?
A
Ppm means parts per million, i.e. one
part of CO in one million parts of air
(breath). This might not seem like very
much, but ppm has a direct correlation
with %COHb – the percentage of CO
combined with haemoglobin in the blood.
If a patient gives a reading of 20ppm (that
of a frequent adult smoker), it means that
their oxygen carrying capacity is reduced
by 5%. It also indicates a high level of
addiction to nicotine.
Q How quickly does CO disappear from the
body when someone stops smoking?
A
It takes about 5-6 hours for the original
level to reduce by half. Usually, an
ex-smoker will show the level as a non-
smoker living in the same environment
after a maximum of 48 hours.
Q How long after a cigarette should the
test be conducted?
A
After a minimum of 10 minutes.
Q What levels of breath CO do you expect
to see?
A
A guideline based on clinical research is
shown in the table on page 10.
Q What is the best time to take a CO
reading?
A
The best time to take a CO reading is as
late as possible in the day.
