Carbon monoxide alarms: where you need one and what the law says

Why it matters

Carbon monoxide is a poisonous gas made by fires and appliances that burn gas, wood, oil or coal. It is colourless and does not smell. Appliances can make it if they are not installed properly, are faulty or are poorly maintained. Using a barbecue or camping stove inside, or running an engine in an enclosed space such as a garage, can also cause a build-up.

The risk tends to rise during power cuts and cold snaps, when people use stoves, heaters or generators they do not normally use.

Which rooms need an alarm

The NHS advises an alarm that makes a loud sound in each room of your home that has an appliance burning gas, oil, coal or wood. That typically includes:

• the room with your gas or oil boiler
• rooms with a gas, wood, coal or multi-fuel fire or stove
• rooms with a gas or paraffin heater

What the law says

England: rented homes

Under the Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022, private and social landlords must fit a carbon monoxide alarm in any room used as living accommodation that has a fixed combustion appliance, such as a boiler or fire. Gas cookers are excluded. Landlords must repair or replace alarms once told they are faulty. The government booklet says alarms should meet British Standard BS EN 50291, and gives positioning advice: at head height, between 1 and 3 metres from the appliance. These rules do not apply to owner-occupiers, but the NHS advice above still does.

Scotland: all homes

Every home in Scotland must have a carbon monoxide detector in any room with a carbon-fuelled appliance, such as a boiler, fire, heater or flue. A detector is not needed for a cooker or hob. See the Scottish Government guidance.

Wales and Northern Ireland

Different rules apply. If you rent, ask your landlord. Otherwise, follow the NHS advice above.

If an alarm sounds or you have symptoms

Symptoms include headache, dizziness, feeling or being sick, weakness, tiredness and confusion, chest and muscle pain, and shortness of breath. They may get better when you go outside and worse when you go back in.

1. Stop using the appliance you think is causing it, if you can.
2. Go outside into fresh air.
3. If you think a gas appliance is leaking, call the free National Gas Helpline on 0800 111 999, 24 hours a day. In Northern Ireland, call 0800 002 001.
4. Get medical advice. Call NHS 111 if you think you have symptoms. Do not go back inside until you have had advice.
5. Call 999 or go to A&E if someone finds it hard to breathe, has become confused, has lost consciousness, or feels weak or has chest or muscle pain. Do not drive yourself to A&E.

Prevention

• Have boilers, heaters and cookers installed properly and serviced regularly by a qualified, registered engineer. For gas, use a Gas Safe registered engineer.
• Keep rooms ventilated and chimneys and flues clean.
• Never use a barbecue or camping stove indoors or inside a tent.
• Never leave engines running in enclosed spaces such as a garage.
• Do not use oversized pans that cover more than one gas ring.

We do not test or recommend specific alarm brands. Check the alarm states it meets BS EN 50291, and follow the maker’s instructions on fitting, testing and replacement.