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Carbon Monoxide (CO) Information

You can't smell, hear or see Carbon Monoxide… How can you protect yourself and your family?

What is Carbon Monoxide?

Carbon Monoxide (chemical symbol: CO) is a colourless, odourless, tasteless and toxic gas created by the incomplete combustion of fossil fuels (gas, oil, coal and wood), as used in our everyday appliances such as heaters, engines and boilers.

Why is Carbon Monoxide dangerous?

Having no colour, smell or taste means that it is very hard to detect.

Inhaling carbon monoxide reduces the blood's ability to carry oxygen, leaving the body's organs and cells starved of oxygen.

Each year, over 50 people die in the UK as a direct result of exposure to Carbon Monoxide Gas (CO). Many more people die through strokes and respiratory illness made worse by inhaling low levels of CO over prolonged periods. Still, more are left with permanent damage and invalidity. Pregnant women are particularly at risk.


The symptoms of mild Carbon Monoxide poisoning are similar to those of viral cold infections: headache, nausea, dizziness, sore throat and dry cough.

More severe poisoning can result in a fast and irregular heart rate, over-breathing (hyperventilation), confusion, drowsiness and difficulty breathing. Ultimately it leads to coma and death.

Concentration of CO in the air Implications of Exposure
50 parts per million (ppm) Safety level as specified by the Health and Safety Executive for a maximum of 30 minutes.
200 PPM Slight headache within 2-3 hours.
400 PPM Frontal headache within 1-2 hours, becoming widespread in 3 hours.
800 PPM Dizziness, nausea, convulsions within 45 minutes, insensible in 2 hours.

Source From:

How to protect yourself and your family

  • Make sure rooms and heaters are well ventilated.
  • Have your chimneys and flues checked regularly.
  • Make sure boilers and heaters are maintained and serviced regularly.
  • Buy a Carbon Monoxide Detector. A Carbon Monoxide Detector will measure the concentration of Carbon Monoxide in a room and sound an alarm if the CO concentration is higher than permitted (as indicated below)

What to do if your carbon monoxide detector goes off

  • Open the doors and windows to ventilate the area.
  • Turn off all fuel appliances where possible and stop using them
  • Evacuate the property immediately leaving the doors and windows open (make sure everybody is accounted for)
  • Call Gas Emergency Services: 0800 111 999   If you believe that the source of carbon monoxide is not a gas appliance, contact either:
    • Oftec (oil) - 0845 658 5080 or
    • HETAS (solid fuel) - 0845 634 5626
  • Get medical help immediately for anyone suffering the effects of carbon monoxide poisoning (headache, nausea), and advise that carbonmonoxide poisoning is suspected.
  • Do not re-enter the property until it has been declared safe.
  • If a faulty gas appliance has been identified call Gas Safe Register - 0800 408 5500 - who will give you names of registered engineers in your area. Or go to its website:
  • Many of the Fire Services in the UK have carbon monoxide testing equipment and can be called in emergencies

Reviewed: 17/10/2017 (doc:49 V1.0). Our articles are reviewed regularly. However, any changes made to standards or legislation following the review date will not have been considered. Please note that we provide abridged, easy-to-understand guidance. To make detailed decisions about your fire safety provisions, you might require further advice or need to consult the full standards and legislation.


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