With the heating being turned up all around the country and more of us staying indoors for longer this Christmas, there's never been a more important time to have a working carbon monoxide (CO) alarm in your home.
So, we've pulled together our top five CO alarm tips and checks to make this winter to help you to feel safe and protected from the dangers of a CO build-up.
We've also spoken to the Council for Gas Detection and monitoring (COGDEM) to find out more about the importance of regularly testing your CO alarms.
Where the CO alarm is located really matters. You'll need a CO alarm anywhere in your home where there's a potential source of CO and this means anywhere that fuel will be burned.
So, if you have a gas boiler in your kitchen and log fire or log burner in your lounge, you'll need two CO alarms.
Testing a CO alarm is dead easy - all you need to do is to hit the test button. If the alarm sounds, you know the product is working. Scroll down for more on CO alarm testing.
CO alarms have a limited life of between five and ten years. After this time, you'll need to replace the alarm with a new one.
The lifetime of the alarm will be clear to see on the box and in the instructions and the alarm will chirp to tell you when its time is up.
But a useful aide memoire is to write the end-of-life date on the alarm itself, that way you'll be able to see when it's approaching the end of the road.
Alarms using replaceable batteries, rather than the sealed variety which work for the lifetime of the alarm, will need to have their batteries replaced every 12 months.
And if you have a mains powered CO alarm, it will also come with a backup battery - to step-in should there be a power cut - and again, this battery will need to be replaced every year.
So, think about the annual battery-replacing process as an MOT for your CO alarm.
Holiday accommodation in the UK should have CO alarms installed, but to make sure you're safe, why not pack a battery powered CO alarm in your case the next time you get a chance to get away? And the same is true of students returning to University - having their own CO alarm is no bad thing.
We spoke to Andy Curtis of the Council for Gas Detection and Monitoring (COGDEM) - the industry body for carbon monoxide alarm manufacturers - about the importance of regularly testing the CO alarms in your home.
Andy told us that testing alarms needs to become second nature and that we should all be testing the alarms in our homes weekly. Andy told us: 'Generally, all you need to do to find out if your alarm will work when you need it to, is to press the test button. And all certified CO alarms run regular self-tests, where they test their battery and circuitry, including the sensor. So, they're also designed to let you know when there's a problem.'
He went on to say: 'But make sure that you follow the instructions in the manual, as alarm testing guidance can differ slightly from manufacturer to manufacturer.'
Last year we tested seven unbranded CO alarms that were purchased from online marketplaces. Each of the seven dangerously unreliable alarms failed to detect CO in our tests at least once and every one of them is a Don't Buy.
So, if the alarm in your home looks like any of those pictured above, you will need to replace it with an alarm that you can rely on.
The good news is there are 16 Best Buy CO alarms on our site which detected the killer gas in every one of the tests we run.