Carbon monoxide is often given the name ‘the silent killer’ because it’s odourless, tasteless, invisible, and can kill with incredible speed.

If you have gas appliances in the home then carbon monoxide poisoning, though not common, is a very real risk.

Understanding how carbon monoxide poisoning can harm you, how you can prevent it and what to do when you think you may have a leak is important. Even if carbon monoxide doesn’t kill, it can still cause severe health problems.

How does carbon monoxide kill?

Time for some biochemistry.

Your red blood cells contain a protein molecule called haemoglobin that binds to the oxygen you breathe in, circulating it through the body before carrying carbon dioxide back to the lungs. But when you breathe in carbon monoxide something disastrous happens: haemoglobin binds preferentially to carbon monoxide over oxygen. This means that the amount of oxygen in your system decreases and leads to oxygen starvation.

How quickly carbon monoxide poisoning takes effect depends on the concentration of the chemical in the atmosphere and in your blood stream. At low levels you will experience several symptoms that you should use as warning signs, which are:

  • Headaches
  • Feelings of nausea and sickness
  • Tiredness

As exposure increases, further symptoms will develop:

  • Dizziness
  • Breathlessness
  • Physical weakness
  • Confusion and disorientation
  • Collapse/fainting

If you continue to breathe in carbon monoxide then you will eventually become unconscious or slip into a coma. The end result could be permanent brain damage or death.

These symptoms can occur in a matter of minutes with high levels, but low level exposure can still lead to gradual organ and neurological damage and eventual death.

One thing to be aware of is that animals and children are at the highest risk of dying quickly from carbon monoxide poisoning and will exhibit symptoms before adults. If you see any symptoms in them then get out of the house as fast as possible and call an emergency plumber to shut off the gas and locate the cause. You should also go to the doctor or hospital and tell them you suspect you have suffered carbon monoxide poisoning.

Common causes of carbon monoxide poisoning in the home

Carbon monoxide poisoning in the home will typically come from any of three sources.

  • Faulty gas appliances, such as a boiler
  • Improperly vented wood-burning stoves
  • Blocked or faulty chimneys with a live fire

What is a carbon monoxide detector?

  • Faulty gas appliances
  • Improperly vented wood-burning stoves
  • Blocked or faulty chimneys with a live fire

The easiest way to have early warning of a carbon monoxide leak is to install a carbon monoxide detector.

Carbon monoxide detectors come in various forms but look a bit like a smoke alarm, and can be fitted to the wall or be freestanding.

Carbon monoxide poisoning

Carbon monoxide poisoning

How carbon monoxide detectors work

There are different types of carbon monoxide detector, all of which work slightly differently. However, they all monitor the level of carbon monoxide in a room, and then emit an audible alarm when these levels exceed certain levels.

The three types are:

  • Biomimetic. Synthetic haemoglobin interacts with an opto-chemical sensor and darkens as levels of carbon monoxide rise. A sensor monitors this and trips the alarm when the synthetic haemoglobin darkens.
  • Semiconductor. A circuit with tin dioxide wires rest on a ceramic baseplate. As the wires are exposed to carbon monoxide their resistance to the electricity flowing through the circuit drops and triggers the alarm.
  • Electrochemical. A fuel cell that will produce a current in relation to the carbon monoxide in the atmosphere. When this reaches a certain level the alarm sounds.

Where to put a carbon monoxide detector

Which? recommends placing a carbon monoxide detector in each room that has a potential source of carbon monoxide. In most homes, this will be where the boiler is located. The detector should be placed:

  • At least one metre away from boilers, cookers and fires
  • At least 15cm from the ceiling
  • Not directly above a source of heat or steam

If you choose a free-standing detector it can also be taken with you when you go on holiday.

What other checks can you do?

Aside from having carbon monoxide detectors, there are some other checks you can do which might reveal a potential leak.

  • Look at the pilot light on your boiler. If everything's fine this should burn blue, but if it's yellow or orange then you might have a leak.
  • If you see any stains or soot around appliances or fires then be sure to get them checked immediately.
  • Check for smoke build‐up in rooms that have working fireplaces and chimneys.

If you suspect you have a carbon monoxide leak then you should leave your home immediately before calling a professional in for help.