Gas network chiefs have issued a warning after a survey revealed that one in ten boilers inspected in Leicester were faulty.
National Grid said that when more than 11,000 gas boilers, cookers and fires were inspected in the city one in ten were found to be faulty.
The findings come from emergency incidents attended by National Grid and inspections by Gas Safe Registered engineers in Leicester between 2010 and 2013.
The statistics were collated by Gas Safe Register – the official list of engineers qualified to work safely and legally on gas appliances.
Following the ninth annual Carbon Monoxide (CO) Awareness week, in November, National Grid is hoping people will take action before Christmas and buy themselves an audible CO alarm.
James Harrison, Head of Network, said: "We want everyone to have a happy, safe Christmas but faulty appliances could lead to gas leaks, carbon monoxide poisoning or even fires and explosions.
"People should make sure all gas appliances are serviced annually by a Gas Safe Registered engineer and, as a back-up, buy an audible carbon monoxide alarm.
"A carbon monoxide alarm may not be top of people's Christmas shopping list but it could save a life."
Every year 40 people in the UK die of carbon monoxide, 200 are hospitalised and a further 4,000 visit accident and emergency departments with the symptoms of carbon monoxide poisoning.
Mr Harrison said: "Our engineers will be working 24/7 over the Christmas and New Year periods responding to emergencies.
"Our contact centre at Hinckley, Leicestershire, is on standby to receive tens of thousands of emergency calls from the members of the public across the country over the festive season.
"If anyone smells gas or experience the symptoms of carbon monoxide poisoning call the National Gas Emergency Service on 0800 111 999 immediately."
National Grid are urging people to follow simple steps to stay gas safe this Christmas which include making sure gas appliances, such as boilers, fires and cookers, are serviced annually by a Gas Safe Registered Engineer.
People should also install an audible carbon monoxide alarm as a back-up and check for warning signs that appliances aren't working correctly, such as lazy yellow or orange flames instead of crisp blue ones, black marks on or around the appliance and too much condensation in the room.
For more information about gas safety and carbon monoxide poisoning go to www.nationalgrid.com.
A list of Gas Safe Registered engineers is available from the Gas Safe Register website at www.gassaferegister.co.uk. Sign up at www.staygassafe.co.uk for a free reminder service.
If anyone has a gas-related emergency they should call 0800 111 999 to report it.
