What is carbon monoxide?



Carbon Monoxide (CO) is a highly poisonous substance produced by the incomplete burning of gas, Liquid Petroleum Gas (LPG), oil or solid fuel. If you have a faulty gas appliance in your home, it could lead to carbon monoxide poisoning.

The most likely situations where this happens is:

  • when a gas appliance or boiler has been incorrectly fitted, badly repaired or poorly maintained
  • flues, chimneys or vents become blocked

Carbon Monoxide poisoning occurs when you breathe in, even a small amount of, the gas. Breathing in CO means it gets into your blood stream and prevents your red blood cells from carrying oxygen around the body. Without this oxygen your body tissue and cells die – so it’s very important you recognise the signs of Carbon Monoxide early. Because even levels that do not kill can cause serious harm to your health when inhaled over a long period of time.

How do I detect Carbon Monoxide in my home or office?

Carbon Monoxide has no smell, taste or colour – but there are two key signs to look for – these are:

  • the flame on your gas appliance (ie a gas cooker) or boiler is lazy, meaning it could be described as bobbing or swaying side to side when there is no apparent “breeze” or strong directional air flow.
  • there is dark staining around or on gas appliances/your boiler, which could signify leakage of combustion into the room

Even if you do not spot either of these signs, there are six main symptoms to look out for:

  • headaches
  • dizziness
  • nausea
  • breathlessness
  • collapse
  • loss of consciousness

A Carbon Monoxide Alarm will give you peace of mind

The Gas Safety Register strongly recommends that all home owners, tenants, landlords and businesses – basically any place where people spend long periods of time during the day and/or night, fit an audible Carbon Monoxide alarm.

A Carbon Monoxide (CO) alarm looks very similar to a smoke alarm and is very easy to fit by following the manufacturer’s instructions. Fitting should take no more than 5-10 minutes and you can purchase a CO Alarm from £15 at any local DIY store or supermarket.


Before purchasing a Carbon Monoxide alarm always make sure it is marked to EN 50291 and have the British Standards’ Kite mark or other European approved organisation mark.

Please remember: While an alarm will alert you to the presence of Carbon Monoxide in your home, or business premises it is no substitute for having an annual gas safety check and regular servicing by a Gas Safe registered engineer.

Further information about Carbon Monoxide

We’ve got lots of useful information on our website, here are just some of the pages you might be interested in:

What you need to know about an annual boiler service from Clarity Heating
Find out what’s involved, what makes and models of boiler we can service, how long it takes and if you have to have one.

Saving energy, saving pennies
Understanding the benefits of a regular boiler service, one of which is the cost savings of having an efficient heating system in your home or office.

What to do if you smell gas
Don’t panic. We’ve got some useful advice on what to do next.

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