Carbon monoxide: What are the symptoms of poisoning and how to tell if I have a leak?

ITV News Consumer Editor Chris Choi explains how lethal carbon monoxide can be


Millions of people across the UK are at potential risk of becoming victims of carbon monoxide poisoning as the number of faulty appliances has increased during the Covid-19 pandemic.

Carbon monoxide is produced when a fuel is not burnt properly. The most common sources are faulty boilers, gas fires and cookers.

New research by Project Shout shows engineers are finding more unsafe appliances than ever before, after regular carbon monoxide checks were paused by coronavirus.

Carbon monoxide is a highly poisonous gas that has no colour, taste or smell and is invisible to human senses. 

Every year in the UK, more than 200 people are hospitalised with suspected carbon monoxide poisoning, which leads to around 50 deaths.

Charities now fear that number could increase with the winter months approaching, along with spiralling energy prices, and cash-strapped families are at further risk of putting themselves and their loved ones in danger.


Julie Fellows told ITV News she was left "gasping for breath" and feeling "really ill" after her boiler leaked carbon monoxide


Julie Fellows told ITV News she became seriously ill and "couldn't breathe" after her boiler leaked carbon monoxide. Her boiler had been due to be serviced in January but it was pushed back until March due to Covid restrictions.

Julie had been feeling severely unwell for a few weeks - but put her symptoms down to Long Covid - and only realised what was happening when her husband heard the carbon monoxide alarm one evening in February. They threw open all windows in the house and within two hours engineers capped the gas supply.

The mother told ITV News: "I really was very poorly, I had visual disturbances, my concentration was going, the room was going round, and I didn’t realise...

"It’s quite scary that if it hadn’t have been for that alarm, well I wouldn’t be here talking now."

The mother believes she would have died without the alarm alerting her and her husband and is urging everyone to get an alarm and to check their devices.

"In the middle of the night for quite a few days before all this happened I was flinging the windows open at night because I couldn’t breathe, I was literally gasping for breath," she added.

“It [an alarm] will save your life. This gas travels all over the house, it doesn’t matter where it is."

What are the symptoms of carbon monoxide poisoning and who is at risk?

According to the NHS, symptoms of carbon monoxide poisoning can sometimes be mistaken for other ailments like the flu, but some signs to look out for are:

  • Headache and tiredness

  • Confusion

  • Dizzy spells

  • Stomach pain, nausea and vomiting

  • Shortness of breath and difficulty breathing

Everyone is at risk of being poisoned, but some groups are more vulnerable than others.

Young children take breaths more frequently than adults do, so are more at risk. 

Those suffering from heart or respiratory problems are more vulnerable to this poisonous gas than healthy adults, while older people are also more likely to develop brain damage.

Pregnant women who inhale carbon monoxide could risk making their unborn children ill. 



What appliances emit carbon monoxide and what are the signs it's faulty?

Carbon monoxide is produced when a fuel is not burnt properly. The most common sources are faulty boilers, gas fires and cookers. Other devices can include:

  • Portable generators

  • Barbecues

  • Clogged chimneys

  • Wood fires

  • Gas or paraffin heaters

It can be hard to tell if an appliance is leaking carbon monoxide, but possible cues can be:

  • Black, sooty marks on the front covers of gas fires

  • Sooty or yellow/brown stains on or around boilers, stoves or fires

  • Smoke building up in rooms because of a faulty flue

  • Yellow instead of blue flames coming from gas appliances

  • Pilot lights frequently blowing out

Wood fires and clogged chimneys can be sources of carbon monoxide

What to do if I think I have a leak?

If you don't have an alarm, it can be hard to tell if you have carbon monoxide poisoning until it's too late.

If you do have an alarm, the device will alert you if there is a leak. A loud alarm is a warning that there are potentially lethal levels of carbon monoxide present. Never ignore this alarm, as further exposure can be fatal.

The first thing to do when an alarm goes off is to open all the doors and windows to try and filter the air.

Stop using all fuel-burning appliances and leave the property. It's important to not turn on any electrical appliances or to smoke, as a spark could ignite a gas explosion.

In you are feeling unwell, call 999. If not, contact the National Gas Service on 0800 111 999.

Don’t re-enter the property until the alarm has stopped and don’t use the appliance again until it has been checked by an expert.



What can I do to prevent carbon monoxide poisoning?

The only effective way to stay safe from carbon monoxide is to have an alarm installed as you can't see it, smell it or taste it. Alarms are reasonably priced, typically around £20.

More than half of homes in the UK (56%) are unprotected, leaving around 40 million people at risk.

Alarms should be installed between one and three metres away from any fuel-burning appliance, as well as in areas like bedrooms and living rooms.

Gas appliances should also be installed and serviced regularly by a Gas Safe registered engineer.

Experts are urging households to check their carbon monoxide alarms are working Credit: PA

How often should my appliances be checked and who pays for it?

You should get your appliances tested every year, according to the Gas Safe Register.

In a rented property, it is the landlord's responsibility to ensure that all equipment is properly maintained. This applies to any heat-generating appliance, regardless of the fuel it uses.

Landlords should provide a gas safety certificate to say an inspection has been done.

If you own your home, you'll need to pay for servicing and maintenance yourself.