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Information for customers

Carbon monoxide

Carbon monoxide is a highly poisonous gas that has no colour, taste or smell, making it impossible to detect without an alarm.


Follow our simple ABC checklist to keep yourself and your family safe


Fit an Alarm


Test it regularly and make sure the Batteries are working


Have an up-to-date gas Check

Carbon monoxide alarms must be audible – they make a loud noise if gas is present. We do not recommend the use of ‘Black Spot’ indicators as these are not as accurate and will not alert or wake you if there is carbon monoxide in your home.

In an emergency

Make sure you know what to do if your alarm goes off or how to spot signs of carbon monoxide poisoning.

If your alarm goes off or you spot other signs of carbon monoxide:

Step 1: Open doors or windows for ventilation and leave the room to get some fresh air.
Step 2: Seek medical advice from your Doctor if you are feeling unwell, or call 999 if it’s an emergency.
Step 3: Turn off all appliances and get them checked by a registered engineer – do not use them until you’re told it is safe to do so.
Step 4: Call the relevant emergency advice line:
  • Gas Emergency Service (24 hours) 0800 111 999
  • Oil (OFTEC) 0845 658 5080
Step 5: If gas appliances are in the property, do NOT smoke, do NOT turn light switches on or off and do NOT do anything to create a spark.

If you feel unwell

If you feel unwell, others or pets are suffering from headaches, nausea, vomiting, dizziness and unconcious seek medical attention immediately.

If someone is seriously ill from carbon monoxide poisoning it is vital that they are removed immediately from the contaminated area, placed into the open air and given pure oxygen, if available. People should be kept at rest, avoiding exertion. You need to call for medical help urgently.

If you receive medical attention, be sure to state that you suspect carbon monoxide poisoning to make sure you receive appropriate treatment, such as a breath or blood test.

If fire breaks out or victims need to be rescued from a property call 999 for the fire brigade.

Where to buy a carbon monoxide alarm

  • Carbon monoxide alarms are available from DIY stores and some supermarkets, or directly from energy suppliers. Portable carbon monoxide alarms are available from around £15 and can be bought from a number of DIY shops, supermarkets, high street stores, gas suppliers or heating engineers.
  • When you buy a carbon monoxide alarm, make sure it meets current European safety standards. Look for alarms marked with the ‘EN50291′ standard. This may be written as BSEN 50291 or EN50291 and with the ‘CE’ mark, both of which should be found on the packaging and product. Alarms will have either a Kitemark or Loss Prevention Certification Board (LPCB) logo to show independent testing and certification.

Where to put a carbon monoxide alarm

When placing and using an alarm in the home it is best to follow the instructions that were supplied with the alarm. If you can’t find these then here are a few guidelines that will help you install your alarm in the home:

  • Follow alarm instructions and place alarms in rooms with fuel burning appliances such as boilers in kitchens and fires in the lounge
  • If you want to fix the alarm to a wall then position it at head height ( i.e. your breathing level), however the alarm does not need to be fixed on a wall (e.g. it can be placed on a table, shelf or bookcase)
  • If you have a portable battery alarm you could place this in the room that you spend most of your time such as a lounge or bedroom – you can even move it from room to room with you
  • As with smoke alarms, test your carbon monoxide alarm regularly with the test button (follow manufacturer’s instructions) and replace the batteries annually or when the low battery signal sounds
  • Do not place the alarm in a cupboard, behind furniture, near an outside door or ventilation ( e.g. extractor fans or cooker hoods)
  • Do not place alarms directly next to fires, boilers, cookers or heaters – the alarm should be at least 1 meter away from any of these appliances
  • Do not place an alarm in areas or near sources of high condensation and steam e.g near kettles, cooker tops, or showers.
  • The alarm should not be placed on a ceiling like a smoke alarm

    You should never ignore a carbon monoxide alarm. Check the manufacturer’s instructions to make sure you can recognise the alarm sound emitted when carbon monoxide is present as well as the low battery signal to avoid any confusion. If the alarm sounds, call the relevant fuel advice line for help and seek medical advice urgently if anyone is feeling unwell.

    If you are a tenant, carbon monoxide alarms may also be available to you from your landlord or local council.

    If you are worried about the threat of carbon monoxide poisoning whilst on holiday in the UK or abroad, you may wish to take a battery-operated carbon monoxide alarm with you. Just take out the batteries whilst travelling. The same battery alarms can be used at home and on holiday.

    Remember that carbon monoxide alarms must never be used in place of annual safety checks. They are a second line of defence. There is no alternative to proper installation and maintenance of your appliances.

    For more technical information and help about alarms and their use contact CoGDEM (the Council for Gas Detection and Environmental Monitoring) on freephone 0800 1694 457.

    Unblock ventilation

    It is dangerous to block ventilation to fires and stoves. If you block ventilation to your appliances it can lead to carbon monoxide poisoning.

    They need a consistent supply of air in order for complete combustion to happen and for the appliance to work correctly. Make sure rooms and heaters are well ventilated and not blocked to stop draughts or to dry clothes.

    If you have a fire or a stove you should empty and check the ash can daily, clean the flue ways at the back of the boiler weekly and clean the throat plates at the top of the room heater monthly. Also check outside vents to ensure that vegetation has not grown over the outlets and blocked air flow.

    Chimneys should be swept at least once a year, preferably before winter, or more often if used heavily. This is important as birds’ nests, falling stonework and rubble, spider webs and leaves can block chimneys and stop or reduce the flow of air.

    Any blockage can alter the combustion balance or can cause carbon monoxide to come into the home instead of being safely vented from the property outside.

    If you are worried about draughts in your home that might be affecting your fuel burning appliances, you should speak to an installation specialist who may be able to recommend a different place for the appliance to be located.

    Know the signs

    Recognising the symptoms of carbon monoxide poisoning and knowing the danger signs around your appliances is the last line of defence.

    The six main symptoms of carbon monoxide poisoning are:

    • Headaches
    • Dizziness
    • Nausea
    • Breathlessness
    • Collapse
    • Loss of consciousness

    Many of the symptoms of carbon monoxide are similar to those of flu, food poisoning, viral infections, or simple tiredness. Other warning signs that suggest carbon monoxide poisoning include symptoms that:

    • Only occur when you are at home
    • Disappear or get better when you leave the home and come back when you return
    • Are seasonal – e.g. headaches during the winter when the central heating is used more often
    • Or other people in your household (including your pets) are experiencing similar symptoms
    • Carbon monoxide poisoning can affect people’s mental ability before they are aware that there is a problem. Any effort that increases the body’s need for oxygen only makes the problem worse, rapidly leading to collapse and potentially death.

    If you experience any of these symptoms, seek immediate medical advice from your Dr, call NHS Direct on 0845 46 47 (NHS 24 in Scotland on 08454 242424) or if it is urgent, call 999 for an ambulance.

    Although you can’t see or smell carbon monoxide, it is possible to identify signs that there may be a strong risk of it being produced.

    Danger signs to look out for around gas and other fuel-burning appliances include:

    • Sooting or yellow/brown staining on or around your appliance
    • Excessive condensation in the room where the appliance is installed
    • Lazy yellow / orange coloured gas flame rather than a sharp blue one
    • Pilot lights that frequently blow out

    Service appliances

    For protection from carbon monoxide poisoning you must have all fuel-burning appliances – including stoves, fires, boilers and water heaters – serviced annually by a qualified and registered engineer.

    All gas appliances should be serviced and safety-checked annually by a Gas Safe registered engineer. Gas Safe Register replaced CORGI in Great Britain and the Isle of Man on 1 April 2009. To check if an engineer is Gas Safe registered visit or call 0800 408 5500.

    For solid fuel appliances, contact HETAS (Heating Equipment and testing approval scheme for solid fuel and biomass heating systems, fuels and services) or 0485 634 5626 and for oil appliances contact OFTEC (Oil Firing Technical Association) or 0845 658 5080.

    If you live in rented accommodation with gas appliances your landlord must provide you with proof that a Gas Safe registered engineer has safety-checked the appliances within the last 12 months.