CO safety: Everything you need to know about carbon monoxide

Almost every household in the UK relies on gas to heat their homes, cook their food, and provide their hot water. We take it for granted that these appliances are completely safe, but, if something goes wrong, deadly levels of carbon monoxide (CO) can build up in your home.

This guide will explain everything you need to know about carbon monoxide, share tips on understanding the potential signs of carbon monoxide, and discuss the importance of carbon monoxide alarms.

What is carbon monoxide?

Carbon monoxide is a toxic and potentially deadly gas that is produced during incomplete combustion. It is colourless, odourless, and humans can breathe it in without ever knowing it. Low levels of CO are found naturally in the atmosphere, and it’s believed the chemical plays some part in our normal bodily functions, but high levels of exposure to CO can be fatal.

How is carbon monoxide produced?

When a fuel source such as gas, oil, coal, or wood burns, it begins to use up nearby oxygen and replaces it with carbon dioxide. As the amount of oxygen available for combustion decreases, the fuel begins to burn differently. Without enough oxygen, the carbon dioxide will turn into carbon monoxide instead, changing from complete to incomplete combustion.

Carbon monoxide poisoning in the home usually occurs due to poorly fitted or faulty appliances in areas with low ventilation. These scenarios allow the appliance to become starved of oxygen and, rather than producing the non-harmful carbon dioxide, they will produce carbon monoxide. Other activities in the home, such as using pots that are too large for the stove, can have the same effect.

In a standard property, there are many appliances that rely on burning fuels that could put you at risk of exposure to this poisonous gas, including:

  • Fireplaces
  • Boilers
  • Cookers
  • Water heaters
  • Central heating systems

Problems generally only tend to arise when appliances aren’t maintained or are kept in areas of poor ventilation.

Why is carbon monoxide dangerous?

Inhaling carbon monoxide reduces the amount of oxygen that’s able to be absorbed by your blood, preventing your body from getting this valuable resource. This can eventually cause death.

The human body relies upon its red blood cells to carry oxygen from the lungs to the areas of the body that need it. A molecule in red blood cells, called haemoglobin, is responsible for carrying the oxygen molecules. The problem is that carbon monoxide binds to haemoglobin over 200 times more easily than oxygen does, taking up space in the red blood cells that would usually be reserved for oxygen. This makes it harder for oxygen to get to where it needs to be, and parts of the body will begin to shut down and die.

A person who is exposed to low levels of carbon monoxide may eventually realise that something is wrong, but it will be hard to determine the exact cause. Because CO has no taste or smell, it can be almost impossible for a human to detect. Understanding the symptoms can help you to detect low levels of CO in your home, but only a carbon monoxide detector can help you if levels begin to rise quickly.

If it’s allowed to build up in the home, CO levels can become fatal. According to the NHS, there are around 60 deaths in England and Wales each year as a result of carbon monoxide poisoning. For this reason, it is recommended that every home has at least one carbon monoxide alarm.

What are the symptoms of carbon monoxide poisoning?

It’s important to be aware of the symptoms of CO poisoning. It is not always obvious, especially if there is only a low-level in your home, so arming yourself with this knowledge could be life-saving.

The most common symptoms are:

  • nausea
  • dizziness
  • tiredness
  • confusion
  • headaches
  • breathlessness

These low-level exposure symptoms can often be mistaken for food poisoning or flu; however, carbon monoxide poisoning will not cause you to have an elevated temperature. Typically, the longer you are exposed to carbon monoxide, the worse your symptoms will become, eventually leading to neurological symptoms, such as:

  • difficulty thinking or concentrating
  • increased irritability
  • frequent emotional changes

In cases of high-level exposure to carbon monoxide, symptoms can onset rapidly and even prevent escape to safety. This can include:

  • impaired mental state
  • feelings of vertigo
  • loss of coordination
  • breathlessness
  • rapid heart rate (over 100 beats per minute)
  • severe chest pain caused by angina or heart attack
  • muscle spasms and seizures
  • loss of consciousness

In severe cases of extreme carbon monoxide exposure, death can occur within minutes. For this reason, it is vital that carbon monoxide detectors are fitted in rooms with potentially dangerous appliances. Every death caused by carbon monoxide poisoning in the home is preventable, and, in the vast majority of cases, a detector would have alerted the victim to the danger.

Please note: Children, the elderly, and those with heart or respiratory problems are more at risk of carbon monoxide poisoning and can be more quickly overcome by the symptoms.

Signs that carbon monoxide is present in your home

It is incredibly important to understand the potential risk factors of CO poisoning so you can look out for any warning signs. Signs that indicate unsafe levels of carbon monoxide in your home include:

  • Your symptoms only occur when you are at home
  • Your symptoms disappear or improve when you leave home
  • Other people in the household are experiencing the same symptoms (including pets)
  • Your symptoms occur seasonally (such as when central heating is used more in winter)

Other physical signs may also indicate that there is an unsafe level of carbon monoxide in your home, including:

  • Soot or yellow/brown staining around or on appliances
  • Pilot lights that frequently blow out
  • Increased condensation inside windows
  • Smoke build-up in rooms due to poor ventilation

Do you live in rented accommodation? Ask your landlord or warden for an up-to-date annual gas safety record to show that your accommodation is gas safe. For more information on this, please read our gas safety for landlords guide.

What to do if you suspect carbon monoxide in your home

If your carbon monoxide alarm sounds or you suspect there may be unsafe levels of carbon monoxide in your home, do the following:

  1. Turn off all appliances
  2. Open all doors and windows
  3. Evacuate the property

Once you are safely outside, call the gas emergency number on 0800 111 999 and report the incident. Even if you feel fine, call your doctor or an ambulance and seek immediate medical attention, as you may still have dangerous levels of carbon monoxide in your system.

How to prevent carbon monoxide poisoning

Understanding how carbon monoxide poisoning can occur is key to being able to identify any potential problems. Servicing your appliances regularly, maintaining your chimneys and flues, and protecting your home from engine exhaust fumes could save the life of you and your family. Our guide to homeowner gas safety will provide you with more advice on keeping your loved ones safe.

Servicing appliances

Your boiler, fireplace, cooker, and central heating system should all be installed by a reputable and fully-qualified engineer. Never attempt to install or service appliances yourself and do not use appliances that have not first been assessed by a professional.

All servicing and installations should be carried out by someone registered with:

It is good practice to be aware of the potential warnings signs that could indicate one of your gas appliances need to be serviced, including:

  • Your appliance is not working properly
  • Your appliance is burning with a lazy yellow or orange flame instead of a crisp blue flame
  • You can see soot or yellow/brown staining around or on appliances
  • The pilot light keeps going out
  • There is increased condensation inside windows

If you notice any of these signs or anything else that seems unusual, get a qualified engineer to check your appliances as soon as possible. Not only will this ensure they are safe to use, it will also improve your appliances’ efficiency and performance.

The easiest way to keep your appliances in top condition is with ‘All England Gas’ homeowner boiler cover. We have a range of plans covering everything from your boiler and gas appliances all the way to your plumbing and electrics.

Maintaining chimneys and flues

Proper ventilation is essential when it comes to protecting your home from the build-up of dangerous gases. It is recommended that all chimneys and flues are maintained regularly by a qualified professional. It is best practice to have your chimneys and flues swept by a professional chimney sweep at last once a year. Qualified chimney sweeps should be a member of one of three professional bodies:

Engine exhaust fumes

Aside from your household appliances, exhaust fumes from petrol- or diesel-powered engines can also emit dangerous levels of carbon monoxide. This is typically not a problem when used outside, but when carbon monoxide is released in an enclosed space, such as a garage or car, serious problems can occur. To protect you and your home from dangerous levels of carbon monoxide poisoning caused by exhaust fumes, keep in mind the following best practices:

  • Don’t leave petrol- or diesel-fuelled lawnmowers or cars running in the garage
  • Regularly check your car’s exhaust for leaks or deficiencies
  • Ensure that exhausts are not blocked before turning the engine on

Carbon monoxide detectors

To keep you and your family safe from potential danger, it is recommended that you install a carbon monoxide detector in every room that contains a gas appliance. Below you will find important information regarding carbon monoxide detectors.

What is a carbon monoxide detector? How do they work?

A carbon monoxide detector is the name for a number of devices that can detect levels of carbon monoxide in your home. These work by sounding an alarm whenever they sense a certain level of CO in the atmosphere of your home.

Broadly, there are three kinds of carbon monoxide detector:

  • Biomimetic sensors change colour when they absorb carbon monoxide, which triggers an alarm.
  • Metal oxide semiconductors use a silica chip to detect carbon monoxide, which triggers an alarm.
  • Electrochemical sensors use electrodes in a chemical solution to sense changes in electrical currents and triggers an alarm.

Do I need a carbon monoxide detector?

The best way to ensure that both you and your family are kept safe from deadly levels of carbon monoxide is to install a detector and alarm in every room that contains a gas appliance in your home. Saying that, a carbon monoxide alarm is your last line of defence and should not be substituted for proper maintenance and regular servicing of your appliances, flues, and chimneys.

You can buy a carbon monoxide detector fairly cheaply at any DIY or hardware store. If you find it difficult to get to the shops, you can also buy them online. You need to check that it has been approved to the latest British or European Standard (BS Kitemark or BS EN50291) and has a battery life of at least five years. For people with hearing difficulties, there are a number of specialist carbon monoxide alarms on the market.

Where should I place a carbon monoxide detector?

It is wise to fit an alarm in each room of the home that contains a gas appliance — this way you can be sure that any detection will occur as quickly and efficiently as possible.

Always read the manufacturer’s instructions before installing your carbon monoxide alarm. Do not use the ‘black spot’ detectors that change colour when carbon monoxide is present, as they don’t make a sound. You want an alarm that will wake you up if you’re asleep, or you may not be aware of early CO symptoms until it is too late.

How to test carbon monoxide detectors

It’s vital that you know your carbon monoxide detector is working, and you can do this by testing it regularly. Every detector has a ‘test’ button, which will let you know whether the device has sufficient power. The only way to check that the detector will set off the alarm is to do just that, and we recommend doing so every month.

You can buy carbon monoxide detector test kits from the same place you bought your detector. This will include a small container full of a high concentration of CO, as well as a plastic housing to surround the alarm. Full instructions will be provided with each kit.

Will a carbon monoxide detector detect a gas leak?

Carbon monoxide detectors are designed to detect CO and will not alert you to a natural gas leak. Fortunately, gas companies use additives in their supply to give it a distinct unpleasant smell, letting you know of its presence.

Please note: A carbon monoxide alarm is no substitute for the proper installation and servicing of your gas appliances. Gas appliances that are left unchecked could be leaking carbon monoxide. If you do not have your gas appliances serviced every year, you could be putting you and your family in danger of carbon monoxide poisoning.

Other carbon monoxide safety tips

Whether you are at home, at a friend’s house, or in the workplace, there are some general carbon monoxide safety tips and best practices that you should follow.

  • Always use appliances for their intended job (don’t use your oven to heat your home).
  • Do not use oversized pots on your stove or place foil around the burners.
  • Do not block air vents or prevent proper ventilation.
  • Avoid the use of gas-powered equipment or tools in the home.
  • Never burn charcoal in an enclosed space, such as on an indoor barbecue.
  • Avoid sleeping in a room that has a gas fire or paraffin heater without a flue.
  • Fit an extractor fan in your kitchen to improve ventilation.

You now know all about the effects of carbon monoxide and how you can keep yourself and your family safe from this potentially deadly gas.

Here at All England Gas, we offer homeowners and landlords year-round cover for boilers and other household appliances, so you can rest easy knowing everything is covered.

Please note: The advice given above it intended as a general guide to carbon monoxide and its effects. For more information on this gas, please visit the NHS or Gas Safe Register.

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