Carbon monoxide: odorless, colorless, lethal | Science| In-depth reporting on science and technology | DW | 21.11.2017
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Carbon monoxide: odorless, colorless, lethal

Carbon monoxide can be a nightmare for unknowing victims. Even the air in shisha bars can put you in the hospital. DW has the facts surrounding CO poisoning.

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Carbon monoxide detectors for hookah bars

Dizziness, nausea and severe headache - three symptoms you're unlikely to be looking for at a shisha smoking lounge. 
But they are what you may very well get. This year alone, 40 people have been admitted to just one university clinic in the German state of North Rhine-Westphalia (NRW) for complications arising from the inhalation of flavored tobacco at shisha bars. They were found to have carbon monoxide poisoning. Doctors in NRW are now calling for CO detectors to be installed at shisha bars in the state to help monitor the odorless, colorless gas which is released when shisha tobacco is burned.

Carbon monoxide can be lethal

In January 2017, six teenagers died in the southern German town of Arnstein after they had spent the night in a garden shed with a defective wood-fired heater. And last week, three migrants had died in a refugee camp on the Greek island of Lesbos because they were using makeshift stoves in tents, according to news agency AFP. 

Carbon monoxide poisoning is associated with a dangerous collection of symptoms - lightheadedness, confusion, headaches and dizziness can all occur from mild acute poisoning,

Greater exposure can result in toxic levels in the heart and central nervous system, which ultimately leads to death.

Schornsteinfeger Schornsteinfeger bei der Arbeit (picture-alliance/dpa/N. Bachmann)

A chimney sweeper measures the CO levels of a heating vent

Although the gas is extremely toxic it is completely odorless, tasteless, colorless and non-irritating, making it extremely difficult to detect, or for someone to notice that they're breathing it in. 

After someone breaths in carbon monoxide it enters the bloodstream, where it then bonds with the haemoglobin in the blood stream to form carboxyhaemoglobin.

As carbon monoxide molecules has a stronger affinity to haemoglobin than oxygen, the oxygen get "crowded out." There's essentially no space left for it on board the red blood cells. It means the oxygen can't be carried in the blood, which ultimately leads to the death and failure of other cells and tissues in the body.

Carbon monoxide is primarily released in to the air when fuels such as gas, oil and coal don't burn completely. Poorly installed or badly maintained boilers, gas fires, water heaters or cookers are common sources of accidental leaks of the dangerous gas.

How do you cure a poisoned patient?

The initial treatment for carbon monoxide poisoning is oxygen therapy in a hospital. This involves asking the patient to breath in 100 percent oxygen to allow the body to gradually replace the carboxyhaemoglobin.

Since normal air contains around 21 percent oxygen, it means the body can flush out the toxic chemicals. Therapy usually continues until the levels of carboxyhaemoglobin in the bloodstream is less than 10 percent. 

In some cases hyperbaric oxygen therapy (HBOT) is used. This process floods the body with oxygen in a pressurized room or tube and can be used if the patient has been under exposure to carbon monoxide for a long period of time or is suspected of having nerve damage. 


If a patient avoids critical damage from poisoning they can often recover, with the time dependent on how much of the gas was in the body. However there are often long-term complications after treatment.

These can involve breathlessness, chest pains, seizures and often loss of consciousness. As well as brain damage in the form of vision loss, hearing loss or even the development of Parkinson's disease. Over exposure can also effect the heart, with many survivors developing coronary heart disease, which can lead to heart attacks. 

According to the British National Health Service 10-15 percent of survivors tend to develop some form of long-term effects of carbon monoxide poisoning. 

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