for Carbon Monoxide in exhaled breath
The Micro CO meter rates Carbon Monoxide in exhaled breath
in parts per million (ppm)
Health New Zealand Ltd has two of these machines.
Supplier: MicroMedical Ltd now
CardinalHealth.com firstname.lastname@example.org, email@example.com
CO in exhaled breath is used for:
Checking for overnight abstinence in research projects. Confirming
that a smoker has not smoked in the past eight hours. Before
first cigarette in the morning, when the cut off was 15 ppm:
we found mean = 9.5, median 10.5 ppm, with 10%
recording the maximum of 15 ppm.)1
After 1st cigarette
after overnight abstinence CO mean was 14.3 ppm,
median 14 ppm, maximum
23 ppm. After excluding those testing with CO =
15 ppm before first cigarette, then the
remainder, after 1st cigarette, averaged 13.3, with median 14 ppm. Thus accepting only volunteers with 0-14 ppm CO excludes only half of those who have already
smoked one cigarette since waking. On the other hand, setting the cutoff
at 10.5 would exclude 42% of smokers with CO under 15 ppm
who claim not to have smoked their first cigarette since waking.1
In short, CO is not
accurate in detecting overnight abstainers, only in detecting quitters
not smoking for at least 24 hours.1
2) Testing for CO poisoning: Diagnosing
excess CO inhaled (for example in a poorly ventilated room or car) in the
previous few hours.
3) Smoking cessation:
Confirming a nonsmoker has not smoked in the past 8 hours. (3-6 ppm, and certainly < 10 ppm)2
CO ppm in exhaled breath
> 20 5
11-20 5 minutes
23: after first 4 cigarettes of the day (half hourly)1
(46 max, 5 minimum)
>3<7 and certainly under 10
Non-smokers, not exposed to second-hand tobacco smoke
Breath holding for 20 seconds
before blowing into the device gives a result close to alveolar CO levels,
in agreement with blood measurements of blood COHb.
In estimating exposure to smoke toxicants, the alveolar resting levels of
CO (as per a smokelyser), can be used to indicate
the depth of inhalation, and without such data, other smoking parameters
such as the amount of smoke inhaled, may be misleading as a measure of
exposure of the lung to inhaled gases.3
CO has a half life of 5 hours,4 suggesting a 25% fall in 2.5 hours. Hourly
smoking will thus result in increasing levels of CO in exhaled breath. The
ratio of exhaled CO, after versus before, is likely to be the same across
After finishing a cigarette the CO in expired air falls
rapidly to the five minute mark, then slowly in the next hour. The
after-cigarette reading should not be made until 5 minutes after the
cigarette is finished.5
CO boost per cigarette The increase in CO from 5 minutes before
to 5 minutes after finishing smoking is 8 ppm,6
but it may be less. Smoking one cigarette every half hour, CO increased by
4.3 ppm per cigarette, with no real difference
between RYO and factory made cigarettes.1
Emissions In tobacco mainstream (mouth) smoke, up to 26 mg
(8700 ppm) is found in the mainstream smoke (max.
1L) of a Holiday cigarette tested in HCI mode.7
(1 ppm =1.15 mg/m3
at 25degC). Of estimated mouth smoke CO, a fifth is detected in
exhaled breath; 79% is retained in
1. Laugesen M, Epton M, Frampton C, Glover M, Lea RA. Hand-rolled
cigarette smoking patterns compared with factory-made cigarette smoking in New Zealand men. BMC Public
2 McEwan A, Hajek P, McRobbie H, West R. Manual of Smoking Cessation.
Addiction Press, 2006. Blackwell Publishing.
Pirogowicz I, Jezowiecka M, Pomorski M, et al. Przegl
Lek. 2004; 61: 1016-9. PMID 1579428 (PubMed
indexed for Medline)
PJ. The effects of a reduced draw resistance cigarette on human smoking
parameters and alveolar CO levels. Imperial Tobacco Research Laboratory.
1978. Bates No. 402424624. http://bat.libary.ucsf.edu
4 Jo WK,
Oh JW. Evaluation of CO exposure in active smokers while smoking using
breath analysis technique. Chemosphere 2003; 53: 207-16.
G. Wintoniuk DM, Taylor RG et al. Time course of end-expired
carbon monoxide concentration is important in studies of cigarette smoking.
Clin Sci (Lond) 1987; 73: 553-5.
Dixon M. Kochhar N. Prasad K et al. Psychopharmacology
2003; 170: 434-442.
Laugesen M. Fowles J. Scope for regulation of cigarette smoke
toxicity according to brand differences in toxicant emissions NZMJ
15 April 2005. www.nzma.org.nz/journal/118-1213/
Feng S, Plunkett SE, Lam K et al. A new method for estimating the retention
of selected smoke constituents in the respiratory tract of smokers during
cigarette smoking. Inhal Toxicol
2007; 19: 169-79.