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New guidance around preventing exposure to carbon monoxide in commercial kitchens has important implications for UK sports stadia

New guidance around preventing exposure to carbon monoxide in commercial kitchens has important implications for UK sports stadia, says ductwork specialist Francesca Smith.

The Health and Safety Executive (HSE) has released guidance for establishments that use solid fuel appliances such as tandoori ovens, charcoal grills and wood-fired pizza ovens. By following the guidance, stadia and arenas with solid fuel appliances on their premises can prevent workers, customers, and even members of the public in neighbouring properties 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. This can result in serious, permanent ill-health effects, or even death, to anyone nearby.

This is particularly important within arenas and stadia as the kitchens, and grease extract, are generally located on the outside of the premises, with the customers inside. If carbon monoxide were to leak, or a fire break out in the grease extract, customers would have to go through danger areas to access the outside.

Stadia managers should also be aware that the issues addressed in the guidance are the tip of the iceberg.


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 & 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. However, many kitchen extraction systems are made from galvanised steel, which is liable to corrosion. This 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. Also ensure 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 commercial 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.

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.


Carbon monoxide gas can build up quickly and overcome people without warning. 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.

Repeated activation of the alarm indicates a problem, which should be thoroughly investigated before the appliance is put back into use. Battery – rather than mains-operated – devices should be tested regularly. If possible, the appliance/alarm should be interlocked with any fitted mechanical ventilation.

Make sure that the extraction system fan stays switched on until all solid fuel has been extinguished, even if nobody is on the premises, by running it 24 hours a day or by interlocking the extraction fan to the carbon monoxide detector. This will protect people in neighbouring properties from any carbon monoxide leaks, and the building will be safe to enter for the next shift, and safe to access out of hours.

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.

Burn only the amount of fuel you need to minimise the amount of carbon monoxide produced and to keep your costs down. Store solid fuel in a dry and ventilated area, or in line with the manufacturer/supplier’s storage instructions.

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.

Tip of the iceberg

What many arena managers don’t know is that cleaning a ventilation system, which can collect highly-flammable grease, can do more damage than good in some instances.

Cleaning usually has to be done with a caustic based chemical, which is highly corrosive. 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. Grease builds up irrespective of the fabrication, which introduces the need for cleaning with a potentially corrosive chemical.

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.

Also, while the guidance states that extraction systems must be examined and tested, at least once every 14 months, and cleaned regularly, stadia 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.

And finally, don’t assume that everything is OK simply because disaster hasn’t yet struck. A ventilation system, or even just a component such as a fire retardant sealant, could be quietly corroding away out of sight, with possibly fatal consequences. Take great care in picking the right suppliers for installation, design, positioning, maintenance and cleaning, to keep people out of harm’s way.


Francesca Smith is Managing Director of ductwork specialist Bright Hygiene.