Why carbon monoxide is known as the silent killer

One of our specialists previously wrote about the poisonous gas H2S, also known as hydrogen sulphide. By the time you notice the smell of this quiet assassin (which is like rotten eggs), it could already be too late.

But there is another “silent killer”, a poisonous gas which develops in a completely different way. Carbon monoxide, the silent killer which claims lives every year: CO, also known as carbon monoxide.

Carbon monoxide: incomplete combustion

Carbon monoxide is a gas which is released as a result of poor or incomplete combustion. Known sources include hot water heaters, boilers, gas stoves and gas fires. However, combustion engines also produce carbon monoxide. A defect, poor maintenance or maladjustment can result in a significant amount of carbon monoxide being released. The properties of this gas and the way in which the human body reacts to it are what make it so dangerous.

Odourless and colourless

Carbon monoxide is odourless and colourless. Its relative density is almost the same as that of air which means that it does not rise or sink but simply mixes very well with air. You might think that’s nothing to worry about. But it is, as the human body reacts in a very strange way when exposed to carbon monoxide.

Carbon monoxide surpresses oxygen

A substance called haemoglobin in the blood transports oxygen around the body. The nasty property of haemoglobin is that it absorbs carbon monoxide more than 200 times faster than oxygen. Carbon monoxide suppresses oxygen in the blood and without oxygen, it is impossible to survive. It only takes a very small concentration of carbon monoxide in the air to result in a potentially fatal outcome.

Symptons of carbon monoxide poisoning

Unlike a poisonous gas such as H2S which is easy to detect because it smells like rotten eggs, carbon monoxide makes its presence known in a very different way. The symptoms of carbon monoxide poisoning include dizziness, nausea and headaches. Symptoms that you would be more likely to associate with the flu or a hangover. If you ignore these symptoms, what will follow is loss of consciousness, the brain being starved of oxygen and shortly thereafter, death.

Signs of carbon monoxide

Symptons of carbon monoxide poisoning

What should you do if you develop symptoms of carbon monoxide poisoning?

  1. Leave the room immediately and go outside into the fresh air.
  2. You should also call the emergency number 1-1-2 immediately. It is important for victims of carbon monoxide poisoning to be treated as soon as possible. Treatment will generally involve administering pure oxygen. The fire service will use special detection equipment to track down and switch off the source.


Prevention is better than cure. Our specialist Trung Phan Thanh has a number of tips on how to prevent carbon monoxide poisoning:

  • A badly installed combustion appliance such as a boiler or stove can be lethal. Always have these installed by an approved installer.
  • Have gas or other combustion appliances serviced regularly. The installer can measure whether an appliance is producing carbon monoxide. Have flue pipes checked regularly too.
  • Avoid the use of heaters and other open appliances. Choose an electric boiler instead or consider getting hot water from a combi-boiler.
  • Make sure that the area in which a combustion appliance is installed is well-ventilated. Leave grilles or windows open.
  • Keep away from exhaust gases from combustion engines. Never leave an engine running in an enclosed space where people may be present.
  • Purchase a carbon monoxide detector and install it in the vicinity of a heater, stove or boiler.

Measuring is knowledge

Gas detection systems and flue gas analysers can prevent a great deal of misery. There are various solutions that can be used for measuring and detecting carbon monoxide, ranging from gas detection for industrial application to devices for analysing the flue gas from boilers and other combustion appliances. For people who have to work in an environment where there is a risk of exposure to carbon monoxide, there are reliable personal gas monitors which use light, sound and vibration to alert the wearer if an excessive concentration is measured.

Protection against carbon monoxide

Dust masks and masks with filter cartridges are certainly not going to help you! However, there are emergency escape masks which will provide short-term protection against CO if you have to be evacuated in the event of a fire, for example. Other respiratory protective equipment includes full-face masks connected to an air line system with an external air supply or fed by compressed air bottles.

Working with carbon monoxide

Is there a risk of carbon monoxide being released at your workplace? If so, then you should always consult a specialist who will be able to advise you on making sure that your workplace is always safe.

Need advice? Call us on +31 (0)88 – 130 6030 or contact Trung (the Netherlands) or Laurent (Belgium).

Trung Phan Thanh

Trung Phan Thanh

Sales Engineer
Laurent Raes

Laurent Raes

Senior Sales Engineer Belgium
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