top of page

Carbon Monoxide: the hidden killer

Updated: Sep 17, 2020

Carbon monoxide is a deadly gas that has no colour, smell or taste. Breathing it in can kill you if you're exposed to high levels.

There are around 60 deaths from carbon monoxide poisoning in England and Wales every year. Many occur in winter months when heating systems are in use, but they can occur all year.

When you breathe it in, it enters the bloodstream and mixes with haemoglobin to form carboxyhaemoglobin. This means that the blood is no longer able to carry oxygen, causing the body's cells and tissue to fail and die.

The symptoms of carbon monoxide poisoning aren't always obvious. Symptoms include:

  • dizziness

  • tension-type headaches

  • feeling and being sick

  • tiredness and confusion

  • stomach pain

  • shortness of breath and difficulty breathing

  • loss of balance, vision and memory

  • difficulty thinking or concentrating

  • frequent emotional changes - easily irritated, depressed or making irrational decisions.

  • intoxication

  • vertigo

  • loss of physical co-ordination (ataxia)

  • breathlessness and a fast heart rate

  • chest pain

  • seizure

  • loss of consciousness / death

Your symptoms may be less severe when you're away from the source of the carbon monoxide, so you should investigate the possibility of a carbon monoxide leak and ask a suitably qualified professional to check any appliances you think may be faulty and leaking gas.

You can lose consciousness within 2 hours if there's a lot of carbon monoxide in the air.

When fuels such as gas, oil, coal and wood do not burn fully, carbon monoxide is produced. Charcoal burning, running vehicles, and cigarettes also produce the deadly gas. It is therefore vitally important that you regularly service and maintain the following using a fully qualified Gas Safe Engineer:​

  • boilers

  • gas fires

  • central heating systems

  • water heaters

  • cookers

  • open fires

Incorrectly installed, poorly maintained or poorly ventilated household appliances are the most common causes of accidental exposure to carbon monoxide.

The risk of exposure to carbon monoxide from portable devices may also be higher in caravans, boats and mobile homes.

Other possible causes of carbon monoxide poisoning include:

  • blocked flues and chimneys

  • burning fuel in an enclosed or unventilated space

  • faulty or blocked car exhausts

  • paint fumes

  • smoking shisha pipes indoors

If you suspect someone may have been exposed to carbon monoxide, remove them from the area immediately, and open windows and doors. Seek immediate medical help. If the person is losing consciousness or suffering from numerous symptoms, dial 999 immediately. Evacuate the building.

Do not attempt to install or service appliances yourself. Anyone carrying out work on installations and appliances in your home must be registered with a relevant association, such as the:

Make sure all chimneys and flues are swept regularly by a qualified sweep who's a member of the:

Protect yourself from carbon monoxide poisoning caused by exhaust fumes:

  • do not leave petrol-fuelled lawnmowers or cars running in the garage

  • make sure your car's exhaust is checked every year for leaks

  • make sure your exhaust is not blocked before turning the engine on (for example, after heavy snowfall)

Install a carbon monoxide alarm in your home to alert you if there's a carbon monoxide leak. They can be purchased from a DIY or hardware store. Many supermarkets also sell them in the hardware section. Make sure it's approved to the latest British or European Standard (EN50291).

Follow the safety tips below to help protect yourself at home and in the workplace:

  • Never use ovens or gas ranges to heat your home.

  • Never use oversized pots on your gas stove or place foil around the burners.

  • Make sure rooms are well ventilated and do not block air vents. If your home is double glazed or draught proofed, make sure there's still enough air circulating for any heaters that are in the room.

  • Do not use gas-powered equipment and tools inside your home if you can avoid it. Only use them in a well-ventilated area, and put the engine unit and exhaust outside.

  • Always wear a safety mask when using chemicals that contain methylene chloride.

  • Do not burn charcoal in an enclosed space, such as on an indoor barbecue.

  • Do not sleep in a room that has an unflued gas fire or paraffin heater.

  • Fit an extractor fan in your kitchen if not already present.

If your carbon monoxide alarm sounds or you suspect a leak:

  • stop using all appliances, switch them off, and open doors and windows to ventilate the property

  • evacuate the property immediately – stay calm and avoid raising your heart rate

  • call the gas emergency number on 0800 111 999 to report the incident

  • do not go back into the property – wait for advice from the emergency services

  • seek immediate medical help – you may not realise you have been affected by the carbon monoxide, and going outside into fresh air will not treat any exposure by itself

Always be aware of the risk of carbon monoxide poisoning and to look out for warning signs.

Pets are often the first to show signs of carbon monoxide poisoning. The smaller an animal or a person is, the faster they'll be affected. Investigate the possibility of a carbon monoxide leak if your pet suddenly becomes ill or dies unexpectedly and their death is not related to old age or an existing health condition.

The above information is gathered from numerous sources, most notably the NHS website.

This article is part of KSH Safety Services' The Four Seasons of Health and Safety campaign.


The Content on Our Site,, including this blog post, does not constitute advice on which you should rely.  It is provided for general information purposes only.  Professional or specialist advice should always be sought before taking any action relating to health and safety in the workplace. We make no representation, warranty, or guarantee that Our Site will meet your requirements, that it will not infringe the rights of third parties, that it will be compatible with all software and hardware, or that it will be secure. We make reasonable efforts to ensure that the Content on Our Site is complete, accurate, and up-to-date.  We do not, however, make any representations, warranties or guarantees (whether express or implied) that the Content is complete, accurate, or up-to-date. If you subscribe via this site, we store your email with our email marketing and website provider Wix. The EU General Data Protection Regulation (GDPR) is a data privacy regulation to protect all EU citizens’ data. It gives our customers, among other requirements, the right to receive or delete all their personal data. If you wish to do this please email us via the Contact us page and we will request this from Wix. This website is © KSH Safety Services

bottom of page