Carbon monoxide safety: what Sussex households need to know

Carbon monoxide has no smell. You cannot rely on noticing an odour to know it is there. CO can be produced by faulty or poorly maintained fuel-burning appliances, and you may have no obvious warning before it starts making someone unwell.

The useful precautions are straightforward: look after your appliances, fit suitable CO alarms and make sure everyone knows what to do if an alarm sounds. We're sharing this advice for Gas Safety Week 2026 to help households around Haywards Heath and the surrounding villages feel better prepared.

If your CO alarm is sounding, get outside

Get everyone into fresh air straight away. Do not stay indoors to investigate or try to silence the alarm. If a gas appliance may be responsible, call 0800 111 999 from outside. Do not re-enter until you have been told it is safe.

If you think you have symptoms of CO poisoning, call NHS 111. Call 999 if suspected exposure is accompanied by difficulty breathing, sudden confusion, loss of consciousness, weakness, or chest or muscle pain. Do not drive yourself to A&E. The NHS carbon monoxide advice explains when urgent medical help is needed.

What is carbon monoxide, and where does it come from?

Carbon monoxide forms when fuel does not burn completely. Gas boilers, fires and cookers can produce it, as can appliances burning oil, coal or wood. Correct installation, maintenance and ventilation all matter. HSE explains the causes and risks.

This is also why barbecues and camping stoves must stay out of houses and tents. Never run a vehicle or generator in an enclosed space. Equipment designed for outside use can become dangerous when its fumes build up indoors.

Would I know if something was wrong?

Possible symptoms include a headache, dizziness, feeling sick, unusual tiredness and breathlessness. They can resemble other illnesses. Symptoms that affect more than one person at home, get worse in a particular room or improve outside deserve attention.

Do not wait for every symptom on a list. If you suspect exposure, leave and follow the urgent advice above. Feeling better outdoors is a reason to get advice, not to go back in and try the appliance again.

Changes around an appliance can also be worth reporting, including soot, unusual staining or a pilot that keeps going out. Flame colour alone is not a reliable safety check: some decorative gas fires are designed to have yellow flames. Never remove a boiler cover to look for a flame. HSE's warning signs are useful background, but they do not replace an engineer's assessment.

Choosing and fitting a CO alarm

Look for an audible alarm that meets BS EN 50291 and carries an appropriate approval mark. A colour-change spot detector will not give the same audible warning. Buy from a reputable supplier and keep the instructions. HSE recommends suitable audible CO alarms.

Follow the manufacturer's guidance for the exact position. The height and distance from an appliance depend on the alarm and the room, so do not simply copy where a smoke alarm has been fitted.

If someone at home is deaf or hard of hearing, ask about suitable visual or vibrating alerts. The government's alarm guidance includes advice on meeting residents' needs. Our guide for carers and families may also help you plan how the warning will be recognised and acted on.

Testing it takes a moment, but the instructions matter

Use the test button as the manufacturer recommends and check the replacement date. Replacing a battery does not give an expired sensor a new life. Do not use flames, exhaust fumes or a gas appliance to test the alarm.

Get familiar with the different sounds your model makes. A low-battery chirp and a CO warning may be different, but do not assume an unfamiliar sound is harmless. If you are unsure whether it is a CO warning, get outside and seek advice.

Why an alarm and a service do different jobs

A CO alarm provides a warning in the home. A service gives an engineer the opportunity to inspect and maintain the appliance, including the checks required by its manufacturer. You need the appliance looked after even when the alarm has been quiet.

After a gas-valve replacement in Burgess Hill in June 2026, our team carried out a gas tightness test and flue gas analysis before returning the boiler to use. The flue gas test checks the gases produced as the boiler burns fuel. It is one of the ways we assess the appliance's operation after that work.

That care continues between repairs through regular maintenance. HSE strongly advises at least annual servicing of gas appliances by a suitably qualified Gas Safe registered engineer. Our boiler service guide explains what a service involves.

Renting your home?

Report a faulty alarm or an appliance concern to your landlord or managing agent promptly. For rented homes covered by England's alarm regulations, landlords must provide a CO alarm in a room used as living accommodation containing a fixed combustion appliance, excluding gas cookers. That legal exception does not mean a gas cooker cannot produce CO.

Our landlord and tenant guide explains the alarm rules alongside annual gas safety checks and records, with links to the government guidance.

One useful job to do today

Find your alarm instructions and replacement date, then check when your appliances were last serviced. If you're unsure what maintenance is due, our local heating team can help you arrange a planned boiler service.

For the rest of this week's advice, visit our Gas Safety Week guide. If an alarm is sounding or someone may have been exposed, use the emergency and medical advice at the top of this page first.