Carbon Monoxide


The silent killer, Carbon Monoxide, you can’t see it, smell it or taste it. Without an alarm, it is near impossible to detect.  Carbon monoxide is produced when carbon fuels like coal, wood, gas and oil are burnt.  So any device that has a naked flame in the home can produce it.  In fairly small doses, <10 parts per million (ppm), it is not that harmful.  Most alarms are triggered around concentrations of 20ppm and greater.

How does it occur? When you burn carbon fuels in oxygen, then ideally you make carbon dioxide and water, but in the instant a reaction occurs there is not always the correct amount of oxygen available and the carbon only fixes to half the oxygen needed to make the more stable carbon dioxide.

How is it poisonous to us? It is toxic because it saturates our red blood cells and stops our bodies transporting oxygen to our organs. Symptoms include

  • dizziness
  • nausea (feeling sick) and vomiting
  • tiredness and confusion
  • stomach pain
  • shortness of breath and difficulty breathing


Get an alarm! If your home has an oil or gas boiler, gas cooker, a working fireplace or other device that burns fuel inside the dwelling you should have carbon monoxide alarms.  The best type are the sealed battery powered type.  These have an integrated battery that lasts for 5-10 years and notifies you when it needs replaced. Plug in types and non-sealed battery types can both let you down, either by power out or battery fault.

Where to fit an alarm? You should have one in the area of the source like in your living room if there is a fire or stove fitted.  If you have a boiler in your garage which is attached to your house then there should be one fitted near the garage door. Not inside the garage. Also at the top of the stairs or near the bedrooms to wake you should it go off in the night.


What a lot of people don’t know is that there are right and wrong positions in the room for an alarm.  Corners can have poor air circulation and may not therefore give a good reading.


In the busy winter heating season, it is easy to forget about the possible causes, perhaps an un-serviced boiler or an un-swept flue.  Always make time to get your heating appliances serviced and your chimney swept, and test your carbon monoxide alarm regularly. It could save your life.

Test Your Smoke Alarm