How to protect residents from carbon monoxide poisoning

What is carbon monoxide?

Carbon monoxide is colourless, odourless and tasteless. Mild poisoning can cause headaches and flu-like symptoms, whilst higher concentrations can lead to collapse, coma or death.

Sometimes referred to as the 'silent killer', it's estimated that around 20 people die from accidental carbon monoxide poisoning every year in England with around 200 major injuries requiring hospitalisation and around 4,000 minor injuries. The view of some medical experts is that some carbon monoxide poisonings are being wrongly diagnosed and therefore under-reported.

How is carbon monoxide able to leak into a room?

Carbon monoxide is produced by incomplete combustion. It can make its way into a room if:

• A combustion appliance such as a boiler or fire is faulty, poorly installed or maintained
• A flue or chimney is blocked or leaky

Carbon monoxide can be generated by any combustion fuel so it’s important that all appliances are installed and maintained correctly.

Carbon monoxide alarms/detectors

Audible CO alarms can be used to detect when CO reaches hazardous levels. They are a useful back-up precaution, but they are not a substitute for the proper installation and maintenance of the combustion appliances (the paragraph below explains what these are).

CO detectors can sense small amounts of carbon monoxide in the air and give occupants early warning of the potential risk of CO poisoning.

Carbon monoxide is slightly lighter than air and can also be found within warm, rising air – such as that from a fire or boiler. For this reason, detectors should be sited and installed in accordance with building regulation guidance.

The building regulations cover carbon monoxide detectors in requirement J3 – in England states 'Where a fixed combustion appliance is provided, appropriate provision shall be made to detect and give warning of the release of carbon monoxide.'  

And in Wales requirement  J3, the requirement states “ Where a fixed combustion appliance is provided, appropriate provision having regard to the design and location of the appliance shall be made to detect and give warning of the release of carbon monoxide at levels harmful to persons”. 

However, this building regulation requirement is currently only limited to CO detectors in newly built dwellings; those created by way of a conversion; or where a new or replacement appliance is being installed. 

Combustion appliances

A combustion appliance is defined in Approved Document J of the building regulations in England and Wales  as being – an 'apparatus where fuel is burned to generate heat for space heating, water heating, cooking or other similar purpose. The appliance does not include systems to deliver fuel to it or for the distribution of heat. Typical combustion appliances are boilers, warm air heaters, water heaters, fires, stoves and cookers.'

Where to fit a CO detector

In England, a carbon monoxide detector should be provided in the room where the appliance is located. In Wales, from the 6^th of January 2025, it is now a requirement that a carbon monoxide detector is fitted in the following: 

(i) In every space (including connected spaces for example attached garages and loft spaces) containing a fixed combustion appliance (including a fixed flued combustion appliance used for cooking), and  

(ii) in high-risk accommodation, that is, a bedroom or principal habitable room (e.g., living room), where a flue serving a combustion appliance passes through these rooms. 

In both cases the carbon monoxide detector should be located; 

• at least 300mm from any wall (for ceiling mounted alarms) 
• at least 150 mm from the ceiling, above the height of any door or window (for wall mounted alarms) 
• between 1m and 3m (measured horizontally) from the appliance. 

Additional guidance on the siting of carbon monoxide detectors can be found in BS EN 50292, this standard also gives recommendations on how and where an alarm is fitted. It states that an alarm shouldn't be fitted:  

• in an enclosed space 
• where it can be obstructed 
• directly above a sink 
• next to a door, window, extractor fan, air vent or similar ventilation opening 
• where the temperature may drop below –10 ºC or exceed 40 ºC 
• where dirt and dust may block the sensor 
• in a damp or humid location 
• in the immediate vicinity of a cooking appliance 

How should it be powered?

Carbon monoxide alarms can be powered by:

• A battery designed to operate for the working life of the alarm. The CO alarm should incorporate a warning device to alert users when the working life of the alarm is due to pass.
• Mains power using fixed wiring (not plug-in types) provided they are fitted with a sensor failure warning device.

Additional rules and guidance apply to residential landlords on the installation of CO detectors for any property that they rent out.

Disclaimer:  

Every care has been taken to ensure that the above content is correct at the time of publication.  Any reliance on the content should be verified by the dutyholder(s) and their professional advisers.  It is the responsibility of the dutyholder(s) and/or person carrying out the work to ensure compliance with the relevant building regulations and associated legislation.

This content is given in good faith by LABC. It is not definitive, and compliance will be a matter for the relevant building control authority to decide as the enforcing body for the building regulations, and ultimately for the appropriate tribunal or court to determine.   

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