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Carbon monoxide and gas at home: how to protect your family from a silent killer

Carbon monoxide and gas alarms: a practical guide

⏱ 2 min read

Alarms, chimney checks, symptoms. A guide based on official advice. The same text is in the free SurvivalZone.app and works without internet.

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Carbon monoxide has no smell, colour or taste. It forms when something burns without enough oxygen: in a boiler, fireplace or water heater, but also from a car in a closed garage.

Every heating season it kills people across Europe. Almost all of those deaths could have been prevented.

A carbon monoxide alarm

  1. A CO alarm is the most important protection. Fit one in the room with the boiler or fireplace and near the bedrooms. Choose alarms marked with the EN 50291 standard. Test them monthly and replace them when the manufacturer says.
  2. If you have mains gas or bottled gas, add a gas alarm. Natural gas is lighter than air, so the alarm goes high; propane and butane are heavier, so low down.

Servicing and ventilation

  1. Have flues and chimneys checked by a sweep every year.
  2. Do not block air vents, even when it is draughty in winter.
  3. After fitting airtight windows, check that the boiler still gets enough air.
  4. Have the gas boiler and water heater serviced as the manual says.

Things never to do

  1. Never use a barbecue, generator, camping heater or gas cooker indoors for heat. Do not leave a car engine running in the garage.

Symptoms

  1. Headache, dizziness, nausea, sleepiness and weakness that ease outdoors may mean carbon monoxide, especially when several people in the house feel the same or a pet is ill too. Open the windows, get outside and call 112.

Checklist

  1. CO alarm by the boiler and the bedrooms
  2. Gas alarm if you have gas
  3. Alarms tested monthly
  4. Chimney checked every year
  5. Air vents kept clear
  6. Boiler and water heater serviced
  7. No barbecues or generators indoors

See also

Frequently asked questions

Where should I fit a carbon monoxide alarm?

In the room with the boiler, fireplace or water heater and near the bedrooms. Follow the manufacturer's instructions.

What are the symptoms of carbon monoxide poisoning?

Headache, dizziness, nausea, sleepiness, weakness. If several people have them at once, get outside straight away and call 112.

Does a smoke alarm detect carbon monoxide?

No. A smoke alarm detects smoke and a CO alarm detects carbon monoxide. A home with a boiler needs both.

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Sources

Official sources are checked automatically every day. Last check: 2026-11-04.

General guidance only; it does not replace the emergency services. If a life is in danger, call 112.