Getting to grips with carbon monoxide guidelines

New guidance around carbon monoxide exposure in kitchens has important implications for schools, says Francesca Smith

Property managers have a duty of care to keep their people and places safe and nowhere is this more important than in the school environment.

The school kitchen is one area where risk is high. Recently, the Health and Safety Executive (HSE) released guidance for all establishments that use solid fuel appliances. By following the guidance, schools with solid fuel appliances on their premises can prevent pupils, staff and visitors from being exposed to harmful levels of carbon monoxide.

The highly poisonous gas, which has no taste, smell or colour, is released when solid fuel is burned and can quickly build up without proper ventilation.


The guidance in Catering Information Sheet No 26 affects the installation, design, positioning and maintenance of solid fuel appliances and their ventilation systems.


When obtaining a solid fuel appliance, seek competent advice on all technicalities relating to installation, ventilation, extraction and maintenance, from organisations such as the official body to approve biomass and solid fuel heating appliances HETAS, Catering Equipment Distributors Association (CEDA), Catering Equipment Suppliers Association (CESA) and the Building and Engineering Services Association (B&ES).


Determine what material your flue/extraction system is constructed from. Stainless steel is not corroded by the gases released during solid fuel combustion. Galvanised steel is liable to corrosion and can potentially leak carbon monoxide, and other toxic gases, into the surrounding areas.

An extraction system and its components, such as induction fans, should be designed to withstand high temperatures and corrosive flue gases. Make sure there is minimal risk of heat being transferred to any combustible materials close to the flue/ductwork.

Ventilation and extraction

Your flue should be located outside the building and must terminate to the external of the building at a safe atmosphere or discharge point. Seek advice from your local authority building control department to make sure that you are compliant with their requirements.

In school kitchens with both a natural draught flue and a mechanical extraction system, gases can be drawn back down the flue into the room. In this instance, having an equal supply of make-up air to compensate for combustion and removal of resulting gases is very important. A competent engineer can advise you on how best to achieve this.

Maintenance, testing and cleaning

Extraction systems for commercial solid fuel appliances must be thoroughly examined and tested, by an expert, at least once every 14 months. School managers should be careful to check for specific stipulations in their buildings insurance warranty. Most insurers won’t pay out in the event of a fire or a carbon monoxide leak, citing non-compliance.

Also have an appropriate regular cleaning and maintenance programme, carried out by professionals, to ensure that your extraction system continues to function properly. A specialist contractor may be needed to clean the extraction system.


A functioning audible carbon monoxide alarm complying with BS EN 50291 should be fitted, in accordance with the manufacturer’s instructions, and people should be evacuated if the alarm goes off.

Selection and storage of fuel

Only use fuel suitable for your appliance, recommended by responsible suppliers/manufacturers, unless your extraction system can safely remove the products of combustion from alternative fuels.

Information, instruction and training

Ensure that workers are aware of the risks and control measures required to operate the solid fuel appliance safely, of the signs and symptoms of carbon monoxide exposure, and how to follow the emergency procedures.

When cleaning needs to be done with a caustic based chemical, any residue can significantly speed up the rate of corrosion and can corrode stainless steel as well as galvanised steel. This can inadvertently worsen a carbon monoxide leak into a building.

Regardless of whether galvanised steel, stainless steel or another material is used, the system needs to be checked for corrosion as part of a rigorous planned safety check.

Cleaning must therefore be tackled by fully trained, skilled and accredited specialist cleaners whose methodology is exact enough to remove all traces of caustic based chemicals.

Francesca Smith is managing director of ductwork specialist Bright Hygiene


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