The CO (carbon monoxide)

A seasonal gas killer, and equipped with a silencer: carbon monoxide (CO)

Each year, carbon monoxide (CO) kills over the course of daily life. For 2013, the poison control centre listed 538 accidents which produced 1,251 victims, including 26 deaths. According to the figures from the Poison Control Centre, most of the victims were claimed during the winter months, between November and February. In 30% of cases, the accidents occurred in the bathroom due to a water heater which was too old or in bad condition.

Tragedies that unfortunately also occur in the student population of ULiège, rendering essential the information designed to reinforce student vigilance, to prevent acute or chronic accidents, or to limit their consequences.

What is CO and where does it come from?

CO is produced during the incomplete combustion (insufficient oxygenation) of organic fuels: wood, butane, natural gas, coal, tabacco, gasoline, fuel oil, oil propane. In a home, several sources of CO may thus coexist, as different heating devices or systems are concerned: log-burning, coal, gas, or fuel oil boilers...water and bath heaters, fireplaces, stoves, mobile heaters, cookers (except electric), makeshift fire basket devices, car engines in garages...

Water heaters are the most involved devices in domestic CO poisoning. With properly-used and maintained devices, the quantity of CO produced is generally safe. However, improper operation or use of these devices in a closed or poorly ventilated environment can result in CO poisoning. Furthermore, in areas with high car density (high traffic street, garages, parking garages), outside air may be involved.

CO is a devious and toxic gas

This colourless and odourless gas is difficult to detect, which makes it all the more dangerous. Less dense than air, it diffuses rapidly into the surrounding air and is inhaled through breathing. In blood, hemoglobin has a 200-fold higher affinity for CO than for oxygen, and CO rapidly binds to hemoglobin (formation of

carboxyhemoglobin, HbCO).

Not only does the quantity of oxygen transported by hemoglobin diminish, but, in addition, the hemoglobin releases less oxygen at the level of tissue, which results in significant tissue damage and rapid asphyxiation of the organs: in the air, 0.1% of CO kills in 1 hour, 1% in 15 minutes, and 10% immediately.

Symptoms of CO poisoning

They are not specific! As soon as the HbCO level reaches 5%, effects are visible at the level of the nervous system, and cardiac and respiratory changes can occur. Loss of consciousness can occur suddenly in the event of an acute accident.

Headaches, blurred vision, troubles maintaining attention are initial signs. At an HbCO level above 15%, nausea, vomiting, dizziness or, more importantly, fainting occur. At higher doses, convulsions and coma occur. In case of chronic exposure, sleep and memory disorders, chest, muscle, abdominal pain can be described.

Often, CO kills in spring and autumn

Cold weather and fog increase the risk. Indeed, the dispersion of fumes is bad during these periods. Stale air rich in CO disperses little or not at all into the atmosphere and the concentration of CO increases in the vicinity of the CO source. The good quality of a heater or device for heating water does not prevent a faulty connection, the poor condition of the chimney, or a backlog during the thaw from provoking an intoxication.

Certain situations favour CO poisoning

poor evacuation of combustion products (obstructed or poorly sized flue pipe)
lack of ventilation in the room where the combustion takes place (eg. use of a barbecue or brazier in sealed rooms, air outlet clogged)
poor maintenance of heating and hot water appliances, or inserts, stoves, cookers, and mobile space heaters

Simple preventative measures are necessary: open window

ensure the maintenance and proper operation of the combustion equipment
have chimneys and exhaust ducts swept at least once a year
ensure adequate ventilation of the premises where the combustion devices are located, especially avoiding plugging and leaving
dirty the air vents
know that measurements of the expired air with a carboxymeter are achievable
Butane, propane and petroleum mobile supplementary heating equipment must only be used intermittently and exclusively in ventilated rooms.
never heat with outdoor camping heaters or by lighting the oven with a gas or wood stove and leaving the door open
regularly clean the burners on your gas stove. If they are dirty, the air-gas mixture is not carried out under good conditions and the burner may go out, especially when it is idling. A well-regulated flame must not blacken the bottom of the pans

What to do in case of accident?

The formation of carboxyhemoglobin is reversible, which makes it possible to eliminate it by respiratory tract either by placing the subject in a healthy atmosphere, or by having him/her breathe in oxygen, possibly at high pressure (hyperbaric oxygen therapy):

remove the person from the exposed room (without putting oneself in danger, as CO is odourless and colourless) and transport him/her to open air
call emergency services
perform a cardiac massage and practice mouth-to-mouth in case of cardiorespiratory arrest
ventilate the premises by opening the doors and windows

The intoxicated (even slightly) individuals will be transported to the hospital and put on oxygen once taken over by the emergency services in order to accelerate the elimination of the carbon monoxide. At the hospital, the most seriously intoxicated will be placed in a hyperbaric chamber for a 90 minute session.