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Prevent CO poisoning

Carbon monoxide (CO) is a poisonous gas that is released during incomplete combustion due to a lack of oxygen.

Poison Control Center
Flemish Institute for Healthy Living

You can read here how and where carbon monoxide is created , what the risk factors and alarm signals are. How you can prevent it and the use of a CO detector are also discussed.

What is carbon monoxide?

It is a colorless, odorless and tasteless gas so you don't notice it. Carbon monoxide is released from fuels such as coal, gas, fuel oil and wood. CO is found in fires, in industrial flue gases, but also in cigarette smoke and car exhaust.

It causes many accidents every year, of which approximately three percent are fatal . In Belgium and France, CO is the most common cause of fatal poisoning accidents.

CO intoxication occurs in all age groups, but two out of three of the fatal cases involve people over 65 and a poorly functioning heater is the main cause.

How and where is carbon monoxide formed?

CO is created:

  • incomplete or poor combustion of all fuels such as coal, gas, fuel oil, petroleum coke, wood and pellets;
  • where the flames are present and therefore always in the room where the (water) heater is located.

But CO can also come through cracks in the chimney (e.g. in the bedroom) or through ceilings, floors or together with combustion gases from an adjacent room. CO can also end up in rooms where there is no flame .

CO cannot be produced by radiators and electric heaters because there is no flame. With central heating, carbon monoxide can only be produced in the room where the boiler is located.

CO is released:

  • naturally , as a result of volcanic eruptions, swamp gas, forest fires;
  • in many industrial activities (e.g. oil refinery, incinerators);
  • by car traffic ;
  • with tobacco smoke ;
  • by motorized equipment powered by fuel;
  • in case of fire ;
  • for heating appliances (both all kinds of stoves and central heating on fuel oil/gas) and water heaters (boilers).

Risk factors

CO poisoning usually occurs with a combination of several risks . You can live at risk for years without being poisoned. But if there is an added risk, things can end less well.

Lack of air supply

Nowadays people insulate their homes very well. This sometimes means that little fresh air is allowed into the room. This shortage of fresh air (oxygen) causes CO formation in the heating device. If this carbon monoxide is released into space, there is a real risk of CO poisoning.

Problems with devices

A problem with a (water) heater can cause CO to be released into the home. In particular , hot water production equipment (water heaters and bath water heaters) remain the most important source of intoxication. Older devices are generally less safe.

The most common problems with these devices are:

  • are not connected to a chimney that removes the combustion gases;
  • poorly controlled, installed or maintained appliances;
  • misuse ;
  • use in a room that is too small and poorly ventilated.

Problems with flue gas discharge or chimney

Many houses still have a chimney built for coal-fired appliances. But often a high-efficiency gas or fuel oil appliance is now connected, meaning the chimney is not adapted to the needs of the new appliance. The maintenance of the chimney is also important and must be done regularly.

Unfavorable weather conditions

Most accidents due to CO poisoning occur between November and April . In some weather conditions, combustion gases are not removed as well or less ventilation is possible. These conditions result in an increasing risk of CO poisoning.

The risk is greatest:

  • in cold weather when you keep all doors closed and cover the cracks;
  • when it gets a little warmer and the heaters are turned off, which means there is little oxygen supply and combustion takes place very incompletely;
  • in calm and stable weather when the chimneys draw less well;
  • in very windy weather when the combustion gases are blown back into the exhaust.

The weather causes both a setback and an inversion.

  • Backwash means that the combustion gases end up in the home via the chimney instead of into the outside air. This risk of kickback is greatest in calm, foggy weather or on sunny days during a colder period (mainly in autumn, winter and spring).
  • Normally, the temperature decreases with height. With temperature inversion this does not happen, which creates a layer of warm air to a certain extent (especially in winter). This warm layer ensures that chimneys 'draw' less well and that the air in the area is not refreshed much. As a result, combustion gases are poorly removed and the risk of CO poisoning is much greater.

During the weather forecast , a warning triangle indicates that the weather is an additional risk factor for CO poisoning. If there are already a few risk factors in the house, the weather can be a decisive factor for CO intoxication.

Human behavior

A higher CO risk arises from improper or incorrect use of equipment such as:

  • leaving the additional heat on for too long;
  • long-term use of a kitchen geyser without a chimney connection for a shower or bath;
  • setting a heater that is too powerful in a room that is too small on too low a setting;
  • seal all cracks with draft strips ;
  • appliances and chimneys poorly or not maintained;
  • Seal ventilation grilles because of the cold.

Alarm signals

  • The same complaints such as headache, nausea, dizziness, vomiting or fatigue in different people at the same time or pets that act strangely.
  • Complaints that always occur under the same circumstances (e.g. when taking a shower).
  • The disappearance of complaints when you leave a certain place may indicate too high a concentration of CO in that room.
  • Soot deposits on the walls around the gas water heater at the connection to the chimney.
  • Yellow instead of blue flames on a gas burner.
  • Abnormally high humidity or condensation in the home.

Prevention

Provide fresh air

  • Do not close all the cracks in windows and doors.
  • Well ventilate every room you visit regularly.
  • Place a special ventilation grille in small rooms and especially in bathrooms where there is a water heater and in rooms that are heated with a portable gas and kerosene heater.
  • Also provide an air supply and exhaust in the outside wall of a kitchen geyser .

Use the device correctly

  • Use a kitchen water heater (smaller than 5 litres) only for the sink.
  • Always consult a professional for advice when purchasing, installing and maintaining your heating appliances and water heaters.
  • Avoid purchasing second-hand equipment as much as possible.
  • Do not use portable heating appliances (unless electric).
  • When using it after a rest period (first use after the summer months), let the stove burn thoroughly to allow the flue gas discharge to dry and the chimney to draw better.
  • Clean the ash pan of a wood or coal stove daily.

Ensure a properly functioning flue gas discharge

  • Never connect appliances with different fuel supplies to the same chimney flue.
  • Do not connect a range hood or dryer to the chimney.
  • Have the chimney swept and checked annually by a professional. This also allows cracks or tears to be quickly detected and repaired. If your chimney is damp, have it checked immediately.

Check your device

  • Provide annual maintenance by a professional for water heaters and heating boilers (both gas and fuel oil).
  • Regularly check the color of the flame of your gas appliance . A blue flame is normal, a yellow flame indicates incomplete combustion and a risk of CO.
  • Check your device regularly for traces of soot or rust .

Avoid dangerous situations

  • Never run the car engine in a closed garage.
  • Do not use a barbecue in the garage or porch, even with the door open.
  • Do not use steam generators or other appliances powered by a motor (other than electricity) indoors . If this is necessary, ensure good air supply and exhaust.
  • Never sleep in a room where a water heater is on or where a portable gas or kerosene heater is burning.
  • Never place a range hood or tumble dryer in an insufficiently ventilated space.

CO detector

A CO detector measures the amount of carbon monoxide (CO) and gives an alarm signal if it detects too much CO . This does not happen at very low quantities (e.g. if there is smoking in the room), but it does happen in time so that you can leave the room if necessary.

It is best to place a CO detector in any room where a combustion appliance and/or chimney is present. Since CO is mainly located in the upper parts of a room, it is preferable to place the device on the ceiling and, if that is not possible, at least 1.5 meters from the floor.

A CO detector for household use must meet the standards NBN EN 50291 and NBN EN 50292 and carry the CE label . In Belgium, such a device costs between 30 and 80 euros.

A CO detector works on the basis of an electrochemical cell that can also be sensitive to other substances such as solvents. In addition, the CO detector must also work flawlessly when dust, grease, moisture, intense heat or large temperature fluctuations are present. However, most domestic CO detectors cannot provide this guarantee , even if they meet European standards. A CO detector is an extra safety measure, but cannot prevent CO. It is therefore better to continue to apply all other preventive measures if you have installed a CO detector.