Carbon Monoxide
Carbon monoxide (CO) is a colourless, odourless gas that, while naturally present in small amounts in the air, can pose serious health risks when concentrated within home environments. It is produced by the incomplete combustion of fuels such as gas, oil, wood, and coal, commonly from household appliances like cookers, heaters, wood burners, boilers, and fireplaces.
Did you know?
Carbon monoxide is often referred to as the “silent killer” due to its undetectable nature by human senses. It is odourless, invisible and has no taste. When inhaled, CO binds with haemoglobin in the blood more effectively than oxygen, forming carboxyhaemoglobin, and reducing the blood’s ability to carry oxygen to cells and tissues. Initial symptoms of CO poisoning include headaches, dizziness, weakness, nausea, and confusion. People often report flu-like symptoms. Prolonged exposure can lead to unconsciousness, brain damage, or even death.
Impact on Domestic Properties:
Indoor CO can accumulate to dangerous levels if homes have poor ventilation or improperly maintained appliances. This is particularly concerning during colder months when doors and windows are often kept closed and heating appliances are used more frequently. Homes with attached garages also pose higher risks if vehicles are left running inside them.
KEY ADVICE
Ensure that you test your carbon monoxide alarms regularly and replace the batteries at least once a year.
How to avoid carbon monoxide poisoning:
Install CO Detectors: In England, all new homes and existing homes where new or replacement fixed combustion appliances are installed must have carbon monoxide detectors installed, as required under Part J of the Building Regulations 2010.
Read Approved Document J here.
In existing homes, you should install carbon monoxide detectors on every level of the house and near sleeping areas. The alarms should be ideally installed on the ceiling, at least 300mm away from any wall, or on a wall, as high as possible above doors and windows, but not within 150mm of the ceiling.
They should be placed at least one foot away from fuel-burning appliances and not obstructed by furniture or curtains.
If you have a garage or attached shed that contains fuel-burning devices, it is essential to install an alarm in those areas as well. Ensure that you test your carbon monoxide alarms regularly and replace the batteries at least once a year. Unlike smoke alarms, CO detectors have a limited life span, so they should be replaced regularly.
Regular Appliance Maintenance: Have a qualified professional inspect and maintain heating systems, water heaters, and any gas, wood, oil, or coal-burning appliances on an annual basis.
Adequate Ventilation: Ensure proper ventilation in appliance areas. Never use portable fuel-burning heaters or barbeques indoors.
Safe Practices in Garage: Never run vehicles or generators inside an attached garage, even if the door is open.
Be Aware of Symptoms: Educate all household members about the signs of CO poisoning and prepare a response plan, including evacuating the home and calling the free National Gas Emergency Helpline 0800 111 999.
Are you a landlord or living in rented accommodation?
The Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 came into force on 1 October 2022.
From that date, all relevant landlords must:
Ensure that at least one smoke alarm is installed on each storey of their homes where a room is used as living accommodation. This has been a legal requirement in the private rented sector since 2015.
Ensure a carbon monoxide alarm is equipped in any room used as living accommodation which contains a fixed combustion appliance (excluding gas cookers).
Ensure smoke alarms and carbon monoxide alarms are repaired or replaced once they are found to be faulty.
The requirements are enforced by local authorities who can impose a fine of up to £5,000 where a landlord fails to comply with a remedial notice.
In the UK, it is estimated that approximately 4,000 cases of carbon monoxide poisoning occur each year, resulting in hospital visits. A significant number of these cases stem from faulty home appliances, underscoring the importance of regular maintenance and the installation of carbon monoxide detectors. The exact number of cases can vary yearly and may be underreported, as symptoms of CO poisoning can resemble those of common illnesses, leading to misdiagnosis.
Further Measures for Safety
In addition to monitoring appliances, ensuring good ventilation in the home is crucial for preventing carbon monoxide (CO) build-up. Adequate ventilation allows fresh air to circulate and helps disperse any hazardous gases that may be released, particularly from heating systems and kitchen appliances. Keeping vents clear and unobstructed can significantly reduce the risk of carbon monoxide accumulation indoors. By using carbon monoxide detectors, following safety guidelines, and maintaining proper ventilation, households can take essential steps to safeguard against the risk of CO exposure.
In conclusion, awareness and proactive measures are key in safeguarding homes from the unseen threat of carbon monoxide.
For more information
Visit: CORGI Services Limited
Visit: CO Research Trust
The NHIC would like to thank the RMI WG2 Consumer Voice members for their contributions to this guide.
Please note that this guidance document, produced by the NHIC, was accurate at the time of its creation. However, information and regulations may have changed since this document was published. Therefore, seeking the most up-to-date information and expert advice is always advisable before making any decisions related to improving your home.
Copyright National Home Improvement Council 2025. Published: June 2025.
