Carbon monoxide

The carbon monoxide is one of the Oxyde S of carbon. Its chemical formula is CO, its Molécule is thus made up of a Atome of Carbone and of an atom of Oxygène; it is Gaz them in the Normal conditions of pressure and temperature.

The carbon monoxide is colorless, odorless and toxic. Produced by any organic matter combustion when the oxygenation of the hearth is insufficient (incomplete combustion), it can be the cause of Intoxication S mortals.

The carbon monoxide is metastable at temperature and environmental pressure. It tends to react with another carbon monoxide molecule to form Carbon dioxide and Carbone, according to the balance of Boudouard. It is according to this reversible reaction that carbon is transported.

Chemistry

It is the theory of the molecular Orbitale S which is most capable to describe the structure of carbon monoxide. The interatomic distance from 0,111 Nm) corresponds to triple partial connection. The molecule presents weak a Dipole moment with a negative partial load on carbon. The carbon monoxide often intervenes in the metallurgy like product of the reduction of certain metals by carbon, iron for example.

The Nickel form with carbon monoxide a compound bird, nickel carbonyl (carcinogenic). This compound breaks up immediately into carbon monoxide and nickel what allows the purification of nickel.

One can produce acetic Acid while making react carbon monoxide and Méthanol with a homogeneous rhodium catalysis (proceeded Monsanto).

The monoxide carbon reacts with dioxygene to form carbon dioxide according to the reaction

2 CO + O - > 2 CO

Biology

Toxicity

The carbon monoxide is emitted by the Automobile S when the temperature is insufficient for a complete oxidation of the Hydrocarbure S of the gasoline out of water and CO₂, insufficient temperature because of one insufficient duration in the combustion chamber or because of an insufficient presence of Oxygène. It is generally more difficult to create a combustion with weak CO rejection than to weak rejection of unburnt residues. The first source of CO for the man is the Cigarette. CO has a strong affinity (230 times higher than that of dioxygene) for the ion Fer of the Hémoglobine, the principal oxygen conveyer in blood. So little CO in the air inspired leads quickly to the formation of Carboxyhémoglobine which replaces the oxyhaemoglobine. The transport capacity of oxygen is decreased and quickly becomes insufficient to bring oxygen necessary to fabrics. In addition, CO blocks enzymes of the respiratory chain mitochondriale: it follows an impossibility for the cell of using the oxygen which reaches him. Thus, the organization suffers quickly from a Hypoxie generalized: hypoxia " of transport" (known as hypoxemic hypoxia) and hypoxia " of utilization" (known as histotoxic hypoxia). The fabrics most sensitive to the lack of oxygen are those which use some more, especially if their energy reserve is weak: the central nervous system and the heart are touched. A sufficient exposure can simply make a person unconscious by reducing the oxygen contribution to the brain, and cause cerebral damage until the death by Anoxie. The carboxyhaemoglobin has a color bright red of such kind that a poisoning with CO can cause a pink color on the level of the cheeks. This coloring known as " color cochenille" is seldom observed in private clinic. It is sometimes noted in the massive intoxications, at the time of the autopsy.

The First aid for an intoxication with carbon monoxide consist in withdrawing the person of the part of exposure (without endangering itself, CO is odorless ), to call the helps, to mass in the event of cardiac arrest, even défibriller if one has the adequate equipment, to insufflate (stops with mouth, balloon). The contribution of oxygen, antidote of the intoxication, is desirable, as quickly as possible. In certain cases, a hyperoxygenation out of box hyperbare will be prescribed.

The leading cause of acute intoxication is the use of boilers and chimneys to the imperfect maintenance or too spaced in badly ventilated parts (winter). Each year of many deaths of the kind is counted. An emergent cause is the use of apparatuses of back up heater (gas, oil,…) functioning in a prolonged way (> 2 hours): these apparatuses use the oxygen of the part where they function and there reject the totality of the gases flarings.

Physiology

The body produces carbon monoxide naturally. The heme of hemoglobin is the substrate of an enzyme (oxygénase) which will produce carbon monoxide and biliverdine. The biliverdine can then be reduced in bilirubine which will be excreted by the liver. On the level of the brain, one could highlight a role of neuro-transmitter at carbon monoxide.

Intoxication with carbon monoxide

The carbon monoxide is a colorless and odorless gas: it is undetectable except by the use of a specific apparatus. Its density is close to that of the air: it is diffused very quickly in the place where it is produced. Its production results from the incomplete combustion of any organic molecule. One can in particular quote: wood, butane, propane, natural gas, coal, gasoline, fuel, oil. As soon as the oxygen concentration decreases on the level of the combustion chamber and in particular when the oxygen concentration becomes lower than 14%, the production of carbon monoxide is majority. It acts like a very toxic gas asphyxiating which, absorbed in a few minutes by the organization, are fixed on the Hémoglobine and on the enzymes of the respiratory chain on the level of the cell. The carbon monoxide has 200 times indeed more affinity for hemoglobin than oxygen.

Among the multiple sources of carbon monoxide, one can in particular quote:

all spark-ignition engines whatever the fuel (cars, generators, motor-driven pumps,…).
fixed systems of heating with combustion.
the apparatuses of back up heater with combustion (which on the one hand consume the oxygen of the part where they function and, on the other hand, reject there the waste gases, of which the carbon monoxide).
apparatuses of production of warm water with combustion.
any apparatus or tools with combustion (cod's head cutter with paper-painted,…).
the combustion of the tobacco, chronic independent source of exposure.

These risks often multiply in the event of bad weather or of storm, where the wind very often drives back gas inside the building.

Many intoxications are due to the faulty operation of heating and the anomaly appliances of ventilation. One also counts the use of carbon monoxide like method of Suicide.

The writer Emile Zola is one of the most famous victim of intoxication to carbon monoxide: He died during his sleep in his residence, the September 29th 1902.

Symptoms

With weak exposure: a frontal headache, nausea S.
With average exposure: a persistent frontal headache with feeling of beats, nauseas, Giddiness S or dizzy spells, somnolence, vomiting, fast Pulse, lowers reflexes and judgment.
With very important exposure: weakness, fainding, Convulsion S, Coma, death.

Headaches and nauseas are the symptoms most frequently met. They are inconstant and nonspecific. The expectant mothers, the elderly and the children of less than two months are more fragile vis-a-vis carbon monoxide.

Exposure time:

It acts like a very toxic gas asphyxiating which, absorbed in a few minutes by the organization, is fixed on hemoglobin:

0,1% of CO in the air kills in one hour
1% of CO in the air kills in 15 minutes
10% of CO in the air kill immediately.

In the cigarette smoke, CO can vary according to the ventilation of the medium, however, it can be present in great quantity because it is released from the incomplete combustion of the components of the cigarette. It should be known that the nonsmoker is exposed more to many toxins (of which CO forms part) that the smoker him even.

With knowknowing

In this case, it is necessary:

to air the buildings immediately by opening doors and windows.
to make evacuate the buildings and empty the places of their occupants.
to call the helps

Treatment

The antidote of the intoxication by carbon monoxide is oxygen. Generally used in normobarie, it is, in the most serious cases, used in hyperbarie in a box of oxygen treatment hyperbare.

Safety

What to make in the event of accident?

The security instructions in the event of accident due to carbon monoxide are simple:

To air the buildings immediately by opening doors and windows.
To make evacuate the buildings and empty the places of their occupants.
To invite the helps
to reinstate the buildings only after the passage of a qualified professional who will seek the cause of the intoxication and will propose work to be carried out.
To contact:

The departmental management of the Sanitary affairs and Social or the central Laboratory of the Police headquarter for Paris and departments 92,93 and 94. These services are able to give you additional details and can intervene to enable you to obtain a help.

Reference UNO for the Transport of dangerous matters

Name (French): Compressed carbon monoxide

* Class: 2

* number: 1016

See too

Carbon dioxide
External bonds and documents
Intoxication with CO (Carbon monoxide) (Urgencies online)
intoxications with the carbon monoxide (French ministry of Health)
intoxication with carbon monoxide - a diagnosis not always easy to pose! (Direction of the Public health of Montreal)
Intoxication by carbon monoxide: current aspects, D. Mathieu, Mr. Mathieu-Nolf, F. Wattel, R. Nevière1, NR. Bocquillon, French company of anesthesia and reanimation

Simple: Carbon monoxide Zh-yue: 一氧化碳

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