Carbon Monoxide in the Home: How to Detect and Prevent It

Updated December 2025

Carbon monoxide is a gas you can’t see, smell, or taste, but it can be extremely dangerous. Because it’s invisible, many people don’t realise it’s present until symptoms appear. Understanding what causes carbon monoxide, how it affects your health, and how to remove it from your home is essential for keeping everyone safe.

What Is Carbon Monoxide?

Carbon monoxide (CO) is a colourless, odourless gas produced when fuels such as gas, oil, coal, wood, or petrol don’t burn properly. It can quietly build up indoors, especially in enclosed or poorly ventilated spaces. Breathing in carbon monoxide prevents your blood from carrying enough oxygen, which can lead to serious illness or even death. This is why it’s often referred to as the “silent killer.”

What Causes Carbon Monoxide in the Home?

Carbon monoxide usually comes from everyday household appliances or activities that involve burning fuel. Common sources include:

1. Gas Appliances

Gas cookers, ovens, water heaters, and gas fires can release carbon monoxide if they’re faulty, poorly maintained, or incorrectly vented.

2. Fireplaces and Wood-Burning Stoves

Blocked chimneys, closed flues, or a build-up of soot can prevent fumes from escaping properly, causing carbon monoxide to flow back into your living space.

3. Furnaces and Boilers

Old or poorly serviced boilers and furnaces are a common cause of carbon monoxide leaks, especially during colder months when they’re used more often.

4. Cars in the Garage

Running a car, even for a short time, in a closed or attached garage can allow carbon monoxide to seep into your home. This risk remains even if the garage door is open.

5. Portable Generators and Fuel-Burning Tools

Generators, barbecues, and fuel-powered tools should never be used indoors or near open windows or doors, as they produce high levels of carbon monoxide very quickly.

Health Effects of Carbon Monoxide Exposure

Carbon monoxide exposure reduces the amount of oxygen reaching your organs and brain. Symptoms can develop gradually or very quickly, depending on the level of exposure.

Early Warning Signs

• Headaches

• Dizziness or light-headedness

• Nausea or vomiting

• Fatigue or weakness

More Serious Symptoms

• Chest pain

• Confusion or difficulty concentrating

• Shortness of breath

• Blurred vision

Severe and Life-Threatening Effects

• Loss of consciousness

• Seizures

• Long-term organ damage

• Death in high concentrations

Because symptoms can feel similar to flu or tiredness, carbon monoxide poisoning is often missed—making early detection crucial.

How to Clear Carbon Monoxide from Your Home

If you suspect carbon monoxide in your home, act immediately:

• Open doors and windows to let fresh air in

• Turn off fuel-burning appliances if it’s safe to do so

• Leave the property immediately if a CO alarm sounds

• Seek medical advice if anyone feels unwell

• Contact a qualified professional to inspect and repair the source

How to Prevent Carbon Monoxide Build-Up

• Install carbon monoxide detectors on every level of your home

• Service boilers, fires, and gas appliances annually

• Keep chimneys and flues clean and clear

• Never use generators, barbecues, or camping stoves indoors

• Avoid running vehicles in enclosed spaces

Understanding carbon monoxide and taking simple preventative steps can make a life-saving difference. With the right awareness, regular maintenance, and proper ventilation, you can keep your home safe, healthy, and protected.

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Carbon Monoxide Safety Checklist (UK Homes)

Use this checklist to help keep your home and family safe from carbon monoxide.

✅ Install Carbon Monoxide Alarms

• Fit carbon monoxide alarms in every room with a fuel-burning appliance (gas, oil, coal, or wood).

• Place alarms near boilers, fires, wood burners, and in bedrooms.

• Test alarms weekly and replace batteries as needed.

• Replace alarms according to the manufacturer’s guidance (usually every 5–10 years).

✅ Service Appliances Annually

• Have boilers, gas fires, and heaters serviced once a year by a Gas Safe registered engineer.

• Ensure oil appliances are serviced by an OFTEC-registered technician.

• Keep service records for peace of mind.

✅ Check Chimneys, Flues & Vents

• Have chimneys swept at least once a year, especially if you use open fires or wood burners.

• Make sure flues and air vents are never blocked or covered.

• Look out for signs of soot, staining, or poor airflow.

✅ Use Appliances Safely

• Never use barbecues, camping stoves, or portable heaters indoors.

• Do not run cars, motorbikes, or lawn equipment in a closed or attached garage.

• Only use fuel-burning appliances as intended.

✅ Ventilate Your Home

• Open windows regularly to allow fresh air to circulate, especially when cooking or heating your home.

• Ensure extractor fans are working properly in kitchens and utility rooms.

✅ Know the Warning Signs

Be alert to symptoms of carbon monoxide exposure, including:

• Headaches

• Dizziness

• Nausea

• Tiredness or confusion

If your alarm sounds or symptoms appear:
➡️ Open windows and doors immediately
➡️ Turn off appliances if safe
➡️ Leave the property
➡️ Call the Gas Emergency Service on 0800 111 999

✅ Extra Tips for UK Homes

• Renters: Check that your landlord has provided CO alarms where required by law.

• Homeowners: Consider upgrading to smart CO alarms for added peace of mind.

• During winter months, be extra vigilant as heating systems are used more frequently.

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