Take a look below at the many questions we frequently get asked by our customers.

The iCOquit® is a personal breath analysis monitor that measures the harmful amount of Carbon Monoxide (CO) exhaled on your breath; the more you smoke, the higher your CO reading will be. Readings are displayed in ppm and give you a visual motivational aid, in the form a traffic light system, to help you quit smoking. Each breath test result is stored within the iCOquit® app, allowing you to track your progress over time. These readings can be used as a tool and education to assist someone to quit smoking, however this still requires ‘will power’ and the ‘want’ to quit!

iCOquit®️ and iCOquit®️ Mums to Be apps are compatible with devices running Android 5 or later, and iOS 9 or later. To see the full list of compatible devices, please visit www.icoquit.com/compatibility.

Carbon monoxide (CO), known as the silent killer, is a colourless, odourless, highly poisonous gas that is produced when fuels are burned incompletely. It is produced in car exhaust fumes, faulty gas boilers and tobacco smoke1. When you inhale smoke from a cigarette, the CO is absorbed into your blood, forming %COHb, which prevents oxygen from being carried around your body to vital organs, resulting in many damaging health effects.

%COHb is the percentage of red blood cells carrying CO instead of oxygen in the blood. When you inhale smoke from a cigarette, CO is absorbed into your blood through the lungs, Oxygen (O2) is carried around the body by red blood cells. CO binds with haemoglobin in the red blood cells to form carboxyhaemoglobin, otherwise known as ‘blood CO’ or %COHb preventing red blood cells from carrying oxygen. CO binds with haemoglobin 200 times more readily than oxygen and a very heavy smoker may have 10% of their blood cells taken up by CO, depriving the body of oxygen.

When a person smokes cigarettes whilst pregnant, the foetus is exposed to elevated levels of %COHb, and as a result the foetal blood will have an increased level of %COHb3, we refer to this calculation as %FCOHb (% Foetal Carboxyhaemoglobin). Simply put, %FCOHb is an estimation of how much CO a foetus has been exposed to.

CO is eliminated through the lungs and has a half-life of approximately 4 hours1. Therefore you must not leave it too much longer than 20-30 minutes after having a cigarette to take a CO reading as it leaves the body relatively quickly. A smoker can blow non-smoker readings approximately 24 hours from going ‘cold turkey’ and quitting smoking completely.

Breath CO readings are displayed in ‘Parts Per Million’ (ppm), which is the number of CO molecules in a million parts of air. Therefore 1ppm of CO denotes 1 part CO for every 1,000,000 parts air, illustrating just how accurate and sensitive the Smokerlyzer® breath CO monitors are. The ppm reading can also tell you how much CO is in the blood (%COHb) using a conversion table.

NICE recommends the lowest threshold for a non-smoker should be 3ppm for pregnant individuals. This is to reduce the likelihood of missing potential smokers and missing opportunities to engage in conversation surrounding smoking habits, so that intervention and treatment for smoking is not delayed in pregnant individuals4.

Smoking – as you would expect, smoking is the main reason for a high CO breath reading and for that reason the CO breath test is seen as the overall best way to validate smoking status and track progress during a quit attempt.

Cannabis/marijuana – regardless of the THC (delta-9-tetrahydrocannabinol) level the levels of carbon monoxide absorbed are three to five times greater than among tobacco smokers2. This may be due to the marijuana users inhaling more deeply and holding the smoke in the lungs and because marijuana has a very high burning temperature compared to tobacco.

Hydrogen – all electrochemical sensors for CO have a certain amount of cross-sensitivity with hydrogen, this means that if there is hydrogen in the breath sample the sensor will see this as CO therefore increasing the reading. Hydrogen is produced in the gut normally in very low concentrations (5-25ppm), but if you have an intolerance to sugars such as lactose or fructose you will produce higher levels of hydrogen after eating one of these sugars. Bedfont® have spent years working with our sensor partners to ensure the lowest possible cross-sensitivity to hydrogen and as a result the iCOquit® has a cross-sensitivity of less than 10%. Therefore even for a very unusually high level of hydrogen on the breath such as 100ppm, the maximum level of ppm added to the reading would be 10ppm on the iCOquit®.

Alcohol – electrochemical sensors are affected by alcohol in high concentrations therefore cleaning wipes or hand gels containing alcohol cannot be used to clean the monitors. Alcohol can permanently damage the CO sensor but usually the sensor will recover from being saturated by alcohol after 24-48 hours left in an alcohol free environment.

Atmospheric CO – after all the above aspects have been considered, atmospheric CO should be investigated. Vast amounts of CO are released into the atmosphere by burning fossil fuels (forest fires, car exhaust emissions, and burning natural gas). People may be chronically exposed to CO as a result of smoking or from the atmosphere7.

CO Poisoning

The answer to this question is subject of some debate, but from over 35 years of experience in breath CO monitoring Bedfont® recommend waiting at least 10 minutes after a cigarette to take a breath CO reading. This is to avoid a higher CO reading than is accurate due to CO being left in the lung from the cigarette rather than CO that has been metabolized and secreted back into the lung.

In short… NO!

E-Cigarette’s (unless quite unique) do not cause combustion to happen, which generally happens when burning a substance, therefore the levels of CO produced are too low to affect an iCOquit® Smokerlyzer. Therefore E-Cigarette users would blow the reading of an non-smoker on these devices.

When testing breath CO, a breath hold needs to be performed in order for the CO level in your blood to equilibrate to the level of CO on your breath. This was clinically evaluated in 1984 by Robert West where he found that ‘CO increased systematically up to 25 seconds of breath holding, with the curve beginning to flatten off at 15 seconds’5. This was supported in 1986 when Anthony Biglan et al writes that the use of 15 second breath hold is acceptable for discriminating between smoker and non-smokers6.

Therefore the manufacturers, Bedfont®, have adopted 15 seconds as our recommended breath hold time period as this appears to be both clinically correct as well as most acceptable for patients using the device.

We recommend that if you are unable to hold your breath for the recommended 15 seconds, to hold your breath for 10 seconds before exhaling into the device. However, it is still advised that a 15 second breath hold time is favourable where possible. It has been shown by studies that a minimum breath hold time of 15 seconds allows the CO in the breath to equilibrate with the CO in the blood8, giving a much more accurate CO result.

Yes, the device is now Bluetooth® compatible and you will no longer need a headphone jack or adapter to operate the iCOquit® Smokerlyzer®.

Please Note: If you are using an Android device, please ensure that location services are enabled when trying to connect via Bluetooth®.

Make sure your Bluetooth® is enabled and that your phone has enough battery. Make sure that you have an internet connection. If you are using an Android device, please ensure that location services are enabled, before pressing the retry button.

Simply wipe the outside of the device with a lightly damp cloth, ensuring that you do not allow water to enter the breath or exhaust ports in the device.  NEVER  use  alcohol  or  cleaning agents  containing  alcohol  or  other  organic  solvents  as  long-term exposure  to  these vapours  will  damage  the CO sensor  inside. NEVER immerse or splash the device in liquid. For more information on cleaning your device, please refer to the ‘Cleaning’ section in the iCOquit® user manual.

Please check your email for a verification email from signup@icoquit.com. The email may be in your junk/spam folders so please mark them as ‘Not Spam’. Once you have received the verification email, follow the instructions in this email to complete registration.
If you have not received the email, please ensure you are using a personal email address (not belonging to a work domain, e.g. janedoe@NHS.net).
For further help, please email help@icoquit.com.

For more help or information, please email help@icoquit.com.


1. Andrew H. Carbon Monoxide ‘The Silent Killer’ Feasibility Study 2009/2010. 1st ed. London: London Ambulance; 2017

2. Blumenthal I. Carbon monoxide poisoning [Internet]. PubMed Central (PMC). 2017 [cited 23 April 2021]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1281520/

3. Causes and clinical significance of increased carboxyhemoglobin [Internet]. Acutecaretesting.org. 2021 [cited 23 April 2021]. Available from: https://acutecaretesting.org/en/articles/causes-and-clinical-significance-of-increased-carboxyhemoglobin

4. Smoking: stopping in pregnancy and after childbirth | Guidance | NICE [Internet]. Nice.org.uk. 2021 [cited 23 April 2021]. Available from: https://www.nice.org.uk/guidance/ph26/chapter/1-recommendations

5. R West 1984. The Effect of Breath-Holding on Expired Air Carbon Monoxide Concentration in Cigarette Smokers. Addictive Behaviors, Vol. 9, pp. 307-309.

6. A Biglan et al 1986. First Versus Second Portion of Expired Air and Duration of Breath Holding in the Sample of Expired Air Carbon Monoxide.

7. Wright, J., 2020. Chronic And Occult Carbon Monoxide Poisoning: We Don’t Know What We’re Missing.

8. West, R., 1984. The effect of duration of breath-holding on expired air carbon monoxide concentration in cigarette smokers. Addictive Behaviors, 9(3), pp.307-309.