A guide to carbon monoxide safety: how to spot carbon monoxide poisoning

25 October 2021 | Celia Topping

Every year, around 60 people die of carbon monoxide poisoning, and thousands more are hospitalised. Being aware of the causes, signs and symptoms of carbon monoxide poisoning could save your life. 

Read on to find out how to protect yourself, your family and your home from carbon monoxide poisoning. 

What is carbon monoxide?

Carbon monoxide (chemical formula, CO) is a highly toxic gas. It’s known as the “silent killer” because it can’t be seen, smelt or tasted. Breathing in this poisonous gas for even a short time can cause long-term organ damage, or even death. 

How does carbon monoxide affect the body?

You can unknowingly breathe in carbon monoxide as easily as normal air, because it causes no irritation to your nose or throat. The carbon monoxide then builds up in your bloodstream – your body replaces the healthy oxygen in your red blood cells with toxic carbon monoxide, starving your organs of the oxygen they need. This can very quickly lead to serious damage. 

How is carbon monoxide produced?

Carbon monoxide is produced when carbon-containing fuels, such as coal, oil, charcoal, wood, kerosene, natural gas and propane, are not burned fully. 

Common myths about carbon monoxide

  • Carbon monoxide (CO) is sometimes confused with carbon dioxide (CO2). CO2 is the gas breathed out by humans. It’s also a greenhouse gas that occurs when fossil fuels are burned, contributing to climate change. Carbon monoxide isn’t a direct greenhouse gas. 
  • Carbon monoxide poisoning is not always caused by faulty appliances. It can simply be caused by lack of good ventilation. A gas boiler might be operating normally, but if the ventilation system is blocked, carbon monoxide could vent back into your home. 
  • Many people don’t consider carbon monoxide a serious problem. But it affects 1,000s of UK residents every year. 

What is gas used for in our homes?

man looking in oven

Two-thirds of UK homes use gas appliances for heating, or cooking, or both – as well as for other everyday domestic appliances like clothes dryers or lighting fixtures. It’s the second most common fuel in UK homes after electricity. Any faulty gas appliance has the potential to leak carbon monoxide. And even appliances that aren’t faulty could cause problems if they’re not ventilated properly. But by following simple gas safety advice, you can keep your home safe, and avoid any unnecessary risks.

Gas is created from fossil fuels, and it’s the burning of these fossil fuels that’s accelerating climate change. At OVO we offer our green upgrade, OVO Beyond, which offsets 100% of the gas you use. 

What are the risks of using gas in our homes?

Modern gas appliances are rigorously checked to a high industry standard, so are as safe as possible. But many homes have old appliances. There are 2 potential dangers:

  1. If an appliance is broken, it can cause a gas leak, which you can smell. This can lead to a fire or explosion if not dealt with immediately. 

If you think you can smell gas, call your regional gas emergency number, and they'll give you advice on what to do to stay safe. 

  1. If an appliance, such as your hob, or boiler, isn’t maintained properly, the gas might be burning incompletely. When gas isn’t burned fully, carbon monoxide is released. This has no smell or taste. 

What are the signs of a carbon monoxide leak? 

It’s vital that you’re aware of any signs of carbon monoxide in your home. So check regularly for:

  • An orange or yellow flame on your gas hob, instead of the usual blue
  • Dark, sooty stains around gas appliances
  • More condensation than normal inside your windows
  • The pilot light on your boiler frequently blowing out

If you notice any of the above, please call your regional gas emergency number, and they'll advise you what to do. 

Can you smell carbon monoxide? 

No. One of the reasons carbon monoxide detectors are so vital is because, unlike natural gas, carbon monoxide is odorless.

What are the symptoms of carbon monoxide poisoning?

The symptoms of carbon monoxide poisoning can easily be mistaken for something else, like a flu, food poisoning, a hangover, or just feeling “under the weather”. It’s crucial that you do not ignore any of these signs. Your life could depend on it.

The 6 main symptoms are:

  • Headaches
  • Dizziness
  • Nausea
  • Breathlessness
  • Loss of consciousness
  • Collapse

Signs that indicate carbon monoxide poisoning, rather than something else include: 

  • Symptoms at home, but which seem to disappear when you leave
  • Other members of your household (including pets) feel unwell with the same symptoms, at the same time

Check the NHS website for more information. 

How long does it take to get carbon monoxide poisoning?

This depends largely on how much carbon monoxide is in the air, as well as your age, gender, and general health. The longer you inhale the gas, the worse yoursymptoms will get, until you can lose consciousness. This can happen within 2 hours, or even 5 minutes if the concentration of carbon monoxide is very high1.   

What to do if you suspect carbon monoxide poisoning

Every second counts if you suspect carbon monoxide is in the air. Follow these steps:

  • Stop using all gas appliances. You can turn off all gas appliances at once by using the “emergency control valve”, found on the pipes leading into your gas meter.
  • Open all doors and windows to get fresh air inside. 
  • Get outside as soon as possible. Stay calm and try not to raise your heart rate. 
  • Call your regional gas emergency number.
  • Seek immediate medical help, as you may not know how badly you’ve been affected. Just being in fresh air alone isn’t enough. 
  • DO NOT go back into your home. Wait for the emergency services. 

Read more about what to do in a gas emergency in our guide. 

How is someone with carbon monoxide poisoning treated?

If you suspect carbon monoxide poisoning, you must get to a hospital as soon as possible. There you’ll be given a blood or breath test. 

The only treatment is inhaling 100% concentrated oxygen. This will be given to you through a tight-fitting mask. Breathing in high-dose oxygen lowers the carbon monoxide in your bloodstream. Although the immediate danger may be over, exposure to carbon monoxide can have very serious long-term effects – such as brain damage and heart problems. 

How to protect you and your family from carbon monoxide poisoning

There are some common-sense steps you can take to minimise the risk of a potentially dangerous situation:

  • Have all your fuel-burning appliances inspected by a trained Gas Safe -registered expert every year.
  • Make sure any new fuel-burning appliances are professionally installed and ventilated. Get them regularly serviced by a Gas Safe-registered expert. 
  • Get carbon monoxide detectors installed in your home by a Gas Safe-registered expert. 

How to become gas safe around your home

As well as getting appliances regularly checked and installing alarms, here are some simple guidelines to follow, to keep your home safe:

In your garage

  • Never leave your car in the confined space of your garage to let it warm up. Carbon monoxide is found in car exhaust fumes. 
  • Don’t run lawnmowers or other gas-powered engine devices in your garage or shed. Confined spaces allow too much carbon monoxide to build up. 
  • Never use an oven or grill to heat your garage or home. 

In your car

  • Don’t ignore even a minor collision. If the prang has caused a break in the exhaust system, you wouldn’t know if it’s leaking carbon monoxide into your car. 
  • If you’re stationary in the car, and decide to keep the engine running to stay warm, make sure there’s nothing blocking the exhaust pipe. A blocked exhaust pipe can cause carbon monoxide to circulate inside the car. 

In your home

  • Never use a cooking appliance – oven, grill or camp stove – to heat your home
  • Replace old heating and air-conditioning units with modern models
  • Check  your heating and air-conditioning system is installed and inspected every year by a trained professional

How can I book a gas safety check? 

If you own your home, you can book an annual gas safety check. The Gas Safe Register has a list of certified engineers in your area. Prices start at around £45, and go up depending on how many gas appliances you own. 

If you rent your home, ask  your landlord when the next gas safety check is coming up. It would also be a good time to ask about installing a carbon monoxide detector. 

If you’re an OVO Energy member on our Priority Services Register, you might qualify for a free gas safety check. Call us on 0330 303 5063 to see if you’re eligible. Or check out our booklet for more information. 

OVO’s eco-friendly upgrade, OVO Beyond, offers 100% carbon-neutral gas, including 15% green gas. And we offset the rest. Plus, you get 5 carbon-busting trees planted every year in your name!

FAQs for staying gas safe at home

Opening a window will help the carbon monoxide disperse a little. But if your detector has sounded the alarm, it’s best just to leave the house as quickly as you can.

With a flow of fresh air, it takes around 5 hours to get rid of half the carbon monoxide in the air2

Yes. Any fire that’s burning something containing carbon, can produce carbon monoxide.

Carbon monoxide has a half-life of 4 hours. So however much you have in your blood stream, it’ll take 4 hours to get rid of half of it3.

Yes. Symptoms of mild carbon monoxide poisoning can easily be mistaken for viral colds, flu, or even just general tiredness. You might get headaches, dizziness, a sore throat, a dry cough, and/or nausea4.

Yes they do, in small amounts. That’s why you shouldn’t burn candles in a room without ventilation5.

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