SGN, the gas distribution network, said on 5 August 2025 that 95% of carbon monoxide (CO) alarms were not tested at all in 2024, and urged households to test their alarms monthly and to take one when travelling1.
The figure comes from the Carbon Monoxide Research and Analysis (CORA) platform, which is supported by Gas Distribution Networks Cadent, Northern Gas Networks, SGN, and Wales and West Utilities, and was analysed from over 50,000 digital (Internet of Things) alarms1. SGN said the results show thousands of households are putting themselves at risk of CO poisoning every day1.
The company said CO is often associated with winter, but that barbecues can give off CO in an enclosed space even after they have gone out, and that pizza ovens, camping stoves, camping heaters and lanterns can emit CO and cause similar dangers if used in an enclosed space1. It said the gas cannot be seen, smelt, heard and does not have a taste, and that symptoms including headaches, nausea, dizziness and breathlessness can be mistaken for other illnesses such as food poisoning, a cold or a hangover1.
Dan Edwards, SGN Social Impact Programme Lead, said:
"CO is known as the 'silent killer' for a reason, it's invisible, it's odourless, and it can be deadly. Having an alarm is essential, but it's just as important to test it regularly to make sure it works"
SGN also said free CO alarms are available to eligible households through its VCMA-funded projects, and that people should note an alarm's expiry date when testing it so it can be replaced before its end of use1. The source does not report how many households have received a free alarm, nor which households qualify as eligible1.
Why it matters for households
A CO alarm only provides protection while it is working, and the CORA data indicates that the great majority of connected alarms in the sample went a full year without a test1. For a home's energy independence, the alarm is the backstop for the appliances a household runs itself: boilers, cookers, fires and any portable or outdoor cooking equipment brought indoors or into a tent1. Because CO has no colour, smell, sound or taste, an untested alarm gives no warning that it has stopped detecting1.
The summer framing matters because the risks SGN lists are not confined to heating season. Barbecues, camping stoves, camping heaters and lanterns are named as sources of CO in enclosed spaces, and holiday rentals may not have an alarm fitted1. Symptoms that resemble food poisoning, a cold or a hangover can delay recognition of exposure1.
What happens next
SGN said it is working with partners through its VCMA-funded projects to get CO alarms to households that need them most, and that eligible households could receive one for free1. No closing date, allocation figure or eligibility criteria are given in the announcement1. SGN directs householders to its carbon monoxide help and advice page for further information1.
Householders can find background on carbon monoxide and home heating safety and step-by-step guidance in how to test and maintain smoke, heat and carbon monoxide alarms.