Carbon Monoxide
The exhaust pipe gas. When you smoke, directly into your lungs.
At a glance
- Also known as
- CO · Kohlenmonoxid
- CAS number
- 630-08-0
- Toxicity
Very high
- Carcinogenic
- Not classified for cancer
- In cigarette smoke
- 13-23 mg per cigarette (ISO 3308 / Health Canada)
What is Carbon Monoxide?
Carbon monoxide (CO) is a colourless, odourless, tasteless gas that forms during incomplete combustion of any carbon-containing material. In blood, CO binds 200 to 300 times more strongly to haemoglobin than oxygen — pushing oxygen out of its transport function. Each cigarette delivers 13 to 23 milligrams of CO directly into the lung (source: ISO 3308 / Health Canada).
Why is Carbon Monoxide in cigarettes?
When tobacco burns, the reaction with oxygen runs oxygen-starved — typical of any glowing ember. Instead of reacting fully to CO₂, a significant fraction remains as CO. With every puff this CO crosses the alveolar membrane into the blood and binds to haemoglobin, forming carboxyhaemoglobin.
What Carbon Monoxide does to your body — short term
Carboxyhaemoglobin transports no oxygen. Smokers typically show CO-Hb levels of 4 to 8 percent in their blood, heavy smokers higher — compared to under 1 percent in non-smokers. Concretely: less oxygen in tissue, faster pulse to compensate, headache, reduced concentration, reduced physical performance. After 8 hours smoke-free, the CO level normalises (source: NHS).
What Carbon Monoxide does long term
Chronically reduced oxygen supply to vessel walls promotes atherosclerosis. Studies document a markedly elevated risk of coronary heart disease, heart attack and stroke — independent of other tobacco toxins. CO is also the main suspect behind the typical reduced endurance and shortness of breath under exertion in smokers.
Where else do you know Carbon Monoxide from?
CO is the gas from car exhaust and forms in any oxygen-starved combustion — faulty gas heaters, closed rooms with charcoal heaters, house fires. Hundreds die annually from acute CO poisoning in Germany alone. Smoking isn't an acute poisoning — it's a chronic, dosed variant.
How it compares
The workplace exposure limit for CO is 33 mg/m³ over 8 hours (DFG MAK). 20 cigarettes a day deliver over 250 milligrams of CO directly into the lung — concentrated into a few minutes of inhalation per day, without the dilution an air-filled room provides.
Workplace exposure limit: 33 mg/m³ (30 ppm, 8 h, DFG MAK)
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