Carbon Monoxide

What causes carbon monoxide?

Carbon monoxide (CO) is produced when fuels like gas, oil, coal and wood don’t fully burn. In the home there are several appliances which can potentially cause a carbon monoxide leak.

These include:

  • Boilers
  • Fires (gas and solid fuel)
  • Furnaces
  • Gas or kerosene heaters
  • Water heaters
  • Gas tumble dryers
  • Charcoal grills
  • Wood stoves
  • Gas cooking stoves
    However, other sources include:
  • BBQs
  • Lawn mowers
  • Camp stoves
  • Motor vehicles
  • Some power tools with internal combustion engines
  • Paint fumes
  • Smoking (particularly shisha pipes)

What are the signs of carbon monoxide in the home?

One of the ways to tell if a gas appliance is working properly is by looking at the flame. If it’s bright blue, it’s likely to be working correctly. If it’s yellowy orange, CO may be present.

Other signs of a carbon monoxide leak include:

  • Brownish-yellow or sooty stains around the appliance
  • Pilot lights that frequently blow out
  • Heavy condensation in the room where the appliance is installed
  • Fumes or smoke in the house
  • Slower than usual burning of solid fuel fires
  • Absence of an upward draft in chimney flues
  • Fallen soot in fireplaces
  • The only definitive way to detect a CO leak and protect your home is to get CO alarm.

The first symptoms of carbon monoxide poisoning include:

  • Chest tightness or shortness of breath
  • Tiredness
  • Nausea
  • Confusion
  • Headaches
  • Dizziness

How to avoid carbon monoxide leaks:

Regular checks and careful attention to ventilation can be all it takes to avoid the risks associated with carbon monoxide poisoning.

  • Get your gas appliances serviced annually by a Gas Safe registered engineer. If you’re responsible for your gas appliances (this is likely to be the case if you own your home)
  • Make sure rooms are well ventilated
  • Never use BBQs, grills or charcoal fuel burners inside, or in unventilated spaces
  • Fit at least one carbon monoxide detector on every level of your home and test them regularly.
  • Have your chimneys and flues checked regularly


This is what can happen when a flue is blocked. The fumes have no way of escaping, so instead they leak into the room.

It’s important to be aware that even in summer, when your heating is likely to be off, it’s still possible to be affected by a CO leak especially as boilers are used regularly to heat water and people are likely to have more BBQs.

If you’re camping, never take a BBQ inside your tent, even if it’s gone out. As the fumes will have no way of escaping, you could suffer from CO poisoning inside your tent.

Carbon monoxide can also seep into properties via shared flues or chimneys and can even permeate through brick walls and plaster, so you could be poisoned in your own home by CO produced next door.

Find out what to do if you suspect a carbon monoxide leak in your home