Boilers get all the attention, but gas cookers can produce carbon monoxide too – and unlike a boiler, your cooker vents straight into the room where you cook, eat and sometimes sleep. Around 60 people die from unintentional CO poisoning in the UK each year, and thousands more attend A&E with symptoms that first present as flu. This is what to watch for, and how to keep your kitchen safe.
Quick answer
Carbon monoxide from a gas cooker is produced when gas burns incompletely – usually because of a blocked burner, poor ventilation or an incorrect installation. Symptoms mimic flu: headache, dizziness, nausea, tiredness. Fit a CO detector certified to BS EN 50291 at head height 1 to 3 metres from the cooker, service the appliance annually with a Gas Safe engineer, and always cook with the extractor on or a window cracked.
How a gas cooker produces CO
Natural gas that burns completely produces carbon dioxide and water vapour. When combustion is incomplete, carbon monoxide (CO) is released instead. CO is colourless, odourless and roughly the same density as air, which is why it kills people who are otherwise alert – there is no warning smell, no colour, no obvious taste.
Incomplete combustion in a cooker is usually caused by:
- Blocked burner caps or clogged jets from years of spillages and overflowing pans
- Yellow or orange flame instead of a steady blue one
- Poor kitchen ventilation with all windows closed and no extractor running
- An extractor drawing air but no replacement air coming in (a “starved” kitchen)
- Incorrect gas pressure or a non-Gas Safe installation
- LPG cookers set up for natural gas or vice versa
The blue-flame test is a rough but useful indicator. A tidy, sharp blue flame is good combustion. Yellow, floppy or sooty flames are your cue to stop, turn off the appliance and call a Gas Safe engineer.
Read also: Gas Safe Register: how to verify your engineer
Symptoms in humans
CO poisoning is easy to miss because it feels like something else. Common symptoms include:
- Persistent headache, especially when you are at home and lifting when you leave
- Dizziness, nausea, breathlessness
- Confusion, poor concentration, memory lapses
- Tiredness that lifts as soon as you leave the property
- Symptoms shared by multiple people in the same house
- Pets seeming listless or unwell for no obvious reason
That penultimate point is the giveaway. When more than one person in a household – or the family pet – shows the same symptoms and improves outdoors, treat it as CO until proven otherwise. Chronic low-level exposure over weeks can cause long-term neurological damage even if no individual episode is severe.
Where to put your detector
A CO alarm is not the same as a smoke alarm and both are needed. In a kitchen with a gas cooker:
- Fit an audible CO alarm certified to BS EN 50291.
- Mount it 1 to 3 metres horizontally from the appliance.
- Place it at head height – CO diffuses, it does not pool at the ceiling like smoke.
- Never right above the cooker or in the direct blast of the extractor.
- Test it monthly using the test button. Replace the whole unit every 5 to 7 years, or per the label.
- Buy from reputable UK retailers – counterfeit alarms sold cheaply online often fail certification.
Read also: Kitchen fire safety: 15 rules everyone forgets
What to do if the alarm sounds
If your CO alarm goes off, treat it as a genuine emergency, not a false positive. In order:
- Turn off all gas appliances at the wall.
- Open windows and doors to ventilate.
- Get everyone out of the property – people and pets.
- Ring the National Gas Emergency Service on 0800 111 999 (24/7, free).
- If anyone is unwell, dial 999 and mention suspected CO exposure – it changes the medical response.
- Do not re-enter until a Gas Safe engineer or the emergency service has cleared the property.
Never assume the alarm is faulty. False alarms exist but are rare. Better to lose an evening than lose a life.
Prevention as a routine
Detection is the last line of defence. Prevention is the first. Get into the habit of:
- Annual Gas Safe service for the cooker, especially in rented homes – this is a legal requirement for landlords via the CP12
- Cleaning burner caps and crowns weekly – a stiff brush and warm soapy water lift most spillages
- Never blocking air vents, even in winter (external air bricks are there for combustion air)
- Cracking a window while cooking on gas, particularly in small kitchens or basement flats
- Getting installations done by a certified Gas Safe engineer only
- Replacing yellow-flaming burners the same week they start playing up
Read also: How to clean a gas hob (safely and thoroughly)
Higher-risk kitchens
Some households need extra vigilance. If any of the following apply, install a second alarm and service the cooker more often than annually:
- Basement or below-ground kitchens with limited natural ventilation
- Studio flats where the kitchen shares space with sleeping areas
- HMOs and shared houses where multiple people cook heavily
- Older properties with original ventilation blocked up during renovations
- Kitchens that share a flue or vent with an older solid-fuel appliance
London flats in period conversions are a particular risk group; original air bricks are often plastered over during refurbs, leaving no combustion air.
Conclusion
Carbon monoxide from gas cookers is preventable. Blue flame, clean burners, working alarm, annual service. If your cooker is new, old, or being moved between properties, book a certified fitter through our gas cooker installation service in London so combustion is set up right and safe from the very first meal.
