Carbon monoxide (CO) poisoning

Last updated: 05/03/2023

Symptoms of carbon monoxide poisoning (CO)

Clinical signs of carbon monoxide poisoning may include:

Numéros pompiers

  • Feeling faint
  • Loss of consciousness
  • State of confusion
  • Muscle weakness
  • Headaches, dizziness
  • Asthenia
  • Anxiety
  • Palpitations
  • Vision problems
  • Abdominal pain
  • Nausea
  • Vomiting without diarrhoea
  • Hypertonic agitated coma

Where symptoms appear in the same place, at the same time of day or of the week, this strongly suggests carbon monoxide poisoning.

First aid treatment

In cases of carbon monoxide poisoning, you should:

  • Immediately ventilate the area by opening doors and windows
  • Evacuate everyone from the area
  • Not return to the premises until a qualified professional has visited to investigate the cause of the poisoning and propose work to be carried out

Causes of poisoning

Each year, 6,000 people in France are victims of carbon monoxide (CO) poisoning, and 300 people die as a result. It is an extremely toxic, asphyxiating gas which is absorbed by the body in a few minutes, and attaches to haemoglobin :

  • 0.1 % of CO in the air kills in 1 hour
  • 1 % of CO in the air kills in 15 minutes
  • 10% of CO in the air kills immediately

In most cases, incidents are the result of:

  • Poor extraction of combustion gases (obstructed or badly proportioned flue)
  • Lack of ventilation in room where the appliance is installed (draught proofed room, blocked air vents)
  • Poorly maintained heating and hot water appliances, wood-burners, stoves, cookers, portable back-up heaters
  • Dilapidated appliances
  • Improper use of some types of appliances (constant use of back-up equipment for example, generators)
  • Incompatibility of different equipment used in the same house (for example, open fireplace and boiler)

Precautions to prevent CO poisoning

  • Check your boiler before the cold weather period. Once a year, get a qualified professional to carry out a thorough check. If you have to be away, you can leave the boiler on low to protect your heating system from freezing
  • Ensure that the chimney flue is in good condition if the boiler is connected to it, whatever material it is made of (brick flue, boxed sections or casings made from aluminium or stainless steel) and that it is completely clear. It must be swept twice a year
  • Check that fumes are vented to the outside of the building. Portable back-up heaters which run on butane, propane or oil and produce combustion gases containing carbon monoxide and nitrogen oxides, should be used only occasionally and in well-ventilated areas. They must be equipped with safety features with atmospheric controls
  • Never use panel heaters designed for large, very well-ventilated rooms to heat your home, even if they have safety features, or camp heaters designed to be used outside. Do not use your oven with the door open as a means of heating. Do not use radiant construction heaters which have no safety features
  • New appliances which run on natural gas must have a CE marking and some top-of-the-range cooking equipment should also carry the NF GAS Selection marking
  • Do not use small, unvented water heaters except occasionally and for short periods of time, 8 minutes at most. They must be installed in a room which is suitably large and ventilated. The minimum room size is 8m3 for a cooking appliance and 15m3 for a small water heater. It is prohibited to install such appliances in a bathroom or shower room, bedroom or living room, and in residences with only one room (studios)
  • It is prohibited to install an extractor hood connected to the outside in a room where there is also an appliance connected to a flue, as this could interfere with the function of the appliance connected to the flue. Opt instead for a recirculating extractor hood and consult a fitter (it could cause problems)
  • Ensure that your building manager carries out maintenance and checking of individual and communal safety devices
  • New gas appliances which are connected to a natural draught flue system already have a safety system to prevent backdraught of combustion gases, called SPOTT (permanent monitoring system for stack ventilation). The operation of this system must be tested when the appliance is serviced
  • Clean burners on gas cookers regularly (there should be a small, blue flame from each outlet). If they are clogged, the air and gas will not be able to mix properly and the burner could be extinguished, particularly when operating on low. A well-regulated flame should not blacken the bottom of a saucepan