Carbon Monoxide

What is Carbon Monoxide?

Carbon Monoxide, or known as CO, is a poisonous, colourless and odourless gas. It is produced by the incomplete burning of carbon-containing fuels. Cigarette smoke contains very high levels of CO. Because Carbon Monoxide can not be smelt or seen and is deadly, it is known as "the silent killer ". Over 200 people die from Carbon Monoxide poisoning each year.

How does Carbon Monoxide relate to smoking and what are the effects?

CO attaches to the haemoglobin in red blood cells this prevents the affected cells from carrying a full load of oxygen around the blood. Carbon Monoxide is actually 200 times more likely to bind itself together with haemoglobin then the oxygen molecule is, and for this reason it is highly toxic. Basically smoking tobacco largely increases the amount of CO substance in your blood. Having too much CO makes it difficult to carry oxygen through the bloodstream . Having less oxygen in your bloodstream can be very harmful.
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Carbon monoxide pays its part in blood clotting as it also thickens the blood by stimulating the production of fribinogen . The outcome is increase in thickness of the blood as it flows through tightened arteries. This results in a decrease of blood flow and then of course the tissues of the human body now lack oxygen. The further the tissues are away from the heart and lungs the greater the effect. It affects the tissues of the feet and hands the most but all tissues in the body are affected.

People with high CO levels in their blood will feel very tired and fatigued. For people with chronic heart disease , it increases chest pain. In healthy people, inhaling higher levels of carbon monoxide may cause flu-like symptoms but with no fever. These are symptoms such as:

- Headaches
- Dizziness
- Weakness
- Sleepiness and loss of energy
- Nausea and vomiting
- Depression
- Confusion
- Disorientation
- Rapid or irregular heartbeat
- Shortness of breath
- Loss of hearing
- Blurry vision
- Seizures
- Cardiac arrest
- Respiratory failure
- Ringing in the ears

With very high levels of CO in the body, perhaps from a heavy smoker, it will cause loss of consciousness or death, it can also cause heart disease. The health effects of CO however varies for each person.

What are levels of CO in a smoker and non smoker?

The normal levels of CO for a non smoker differs on the levels in the air but it is usually between 0 and 8 parts per million . The CO level for a smoker varies on the time of day, the number of tobacco products smoked and how the smoke is inhaled. For someone who smokes a packet of cigarettes per day will likely have the CO level of about 20 parts per million. If they smoke two packs a day the may have a level of about 40 parts per million.

Where is Carbon Monoxide is normally found?

Carbon Monoxide is found in of course tobacco smoke, but it can be found and emitted in places such as:
  • car exhaust
  • indoor charcoal grills
  • faulty fireplaces and chimneys
  • fires
  • fuel burning equipment such as gasoline engines, gas logs, and gas space heaters
  • faulty gas water heaters or clothes dryers
  • gas appliances and heaters in cabins or campers, pools, and spas

How to test for CO levels in a person

Many years ago there was only one way to measure how much smoke and CO someone had absorbed. It was to take a blood sample and send it into a lab for analysis. Now we can test for CO by a quick and simple breath test . Most smoking cessation clinics use a CO monitor when assessing smokers to get an estimate of how much smoke they are inhaling and it is a way to also monitor the progress of the smoker’s treatment.
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Take a look at some informative pictures about smoking


These two images are titled 'Cigarettes Smoke People'

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This is a very powerful video on smoking and can be found also by visiting

Anti Smoking Australian Commercial (2008)

This is a very short video on Carbon Monoxide and Tar from a smoker
Carbon Monoxide and Tar Dangers

This video talks about cars however the things he says at the start of the video about Carbon Monoxide don't just relate to cars but to smoking too and shows how dangerous CO is.

Cars and Carbon Monoxide

Staying Safe In Your Car:
Cars And Carbon Monoxide Poisoning

What is a Carbon Monoxide Monitor

Quit Smoking:
What is a carbon monoxide monitor?

"A carbon monoxide monitor is a very good way of measuring the levels of carbon monoxide that you have in your system. Once a smoker has actually stopped smoking, the carbon monoxide levels are actually significantly reduced after 48 hours and it's one of the many, very quick and immediate health benefits of stopping smoking."
Ruth Bosworth

This video is found at
It would be worth having a look at as there are other videos on the same site with information on different topics about smoking.

Handy Links For Further Information