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Carbone Monoxyde

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I N D E X

About Carbone Monoxide
Responding to activation of CO detectors - Increased workload for fire dept.
Preparing for response - CO and it's effects - Treating CO poisoning
Triage of calls - Recognize the symptoms - Guidelines for response
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Carbon Monoxide

Chemical compound of carbon and oxygen with the formula CO. It is a colorless, odorless gas, about 3 percent lighter than air, and is poisonous to all warm-blooded animals and to many other forms of life. When inhaled it combines with hemoglobin in the blood, preventing absorption of oxygen and resulting in asphyxiation.

Carbon monoxide is formed whenever carbon or substances containing carbon are burned with an insufficient air supply. Even when the amount of air is theoretically sufficient, the reaction is not always complete, so that the combustion gases contain some free oxygen and some carbon monoxide.

An incomplete reaction is especially probable when it takes place quickly, as in an automobile engine; for this reason, automobile-exhaust gases contain harmful quantities of carbon monoxide, sometimes several percent, although antipollution devices are intended to keep the level below 1 percent. As little as 1/1000 of 1 percent of carbon monoxide in air may produce symptoms of poisoning, and as little as 4 of 1 percent may prove fatal in less than 30 min. Carbon monoxide is a major ingredient of the air pollution in urban areas.

Because it is odorless, carbon monoxide is an insidious poison. It produces only mild symptoms of headache, nausea, or fatigue, followed by unconsciousness. An automobile engine running in a closed garage can make the air noxious within a few minutes; a leaking furnace flue may fill a house with unsuspected poison. Fuel gas, which may contain as much as 50 percent carbon monoxide, often has small quantities of unpleasant-smelling sulfur compounds purposely added to make leaks noticeable.

Carbon monoxide is an important industrial fuel because it contains more than two-thirds of the heating value of the carbon from which it was formed. It is a constituent of water gas, producer gas, blast furnace gas, and coal gas. In smelting iron ore carbon monoxide formed from coke used in the process acts as a reducing agent, that is, it removes oxygen from the ore. Carbon monoxide combines actively with chlorine to form carbonyl chloride, or phosgene, and it combines with hydrogen, when heated in the presence of a catalyst, to form methyl alcohol. The direct combination of carbon monoxide with certain metals, forming gaseous compounds, is used in refining those metals, particularly nickel.

Carbon monoxide melts at -205 C (-337 F) and boils at -191.5 C (-312.7 F).

 

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Responding to activations of carbone monoxide detectors

Carbon monoxide (CO), a potential killer, is produced by all fuel-burning appliances in the home. Until recently, there was no sure method of warning of dangerous levels present in the home. Now, readily available and affordable carbon monoxide detectors routinely provide such a warning and have been credited with saving lives. It appears that the problem has been solved. Why, then, are fire departments across the country so concerned about the carbon monoxide issue?

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Increased workload for fire departments

With the solution to the carbon monoxide threat in homes came an increased workload for fire departments. When the detectors alarm as carbon monoxide builds up in the home, homeowners call the fire department, in accordance with manufacturers instructions included with the detector. In December 1994, the Chicago (IL) Fire Department responded to 1,851 carbon monoxide detector alarms in a 24 hour period. This occurred during a thermal inversion in which a layer of cold air was trapped under a layer of hot air, preventing pollutants, including carbon monoxide, from escaping into the atmosphere. The carbon monoxide reached a level high enough to set off many of the recently mandated carbon monoxide detectors installed in homes around Chicago.

Your department may never have to respond to 1,851 alarms in 24 hours, but your carbon monoxide responses certainly will increase. In 1992, fewer than 1,800 detectors were sold. In 1994, more than five million were sold. That number is expected to increase in 1995 as more and more companies produce carbon monoxide alarms and more homeowners protect themselves by purchasing them. Other municipalities certainly will mandate the use of these alarms. Perhaps your community will be among them. If you have not yet been concerned with carbon monoxide, don't worry; you will be.

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Preparing for response

In an effort to make houses more energy-efficient, the objective becomes to try to keep heated or cooled air in while keeping unconditioned air out. This approach may have saved homeowners money, but it also allowed carbon monoxide and other pollutants to build up in homes, sometimes to dangerous levels.

The recent proliferation of carbon monoxide detectors in homes gives the fire service the opportunity to provide a new service to those we protect. How well we prepare to perform this service could mean the difference between life and death for entire families.

Being prepared entails the following:

  • knowing what carbon monoxide is and how it affects victims,
  • knowing how to treat victims overcome by carbon monoxide,
  • recognizing a carbon monoxide detector and understanding how and why its alarm sounded, and
  • knowing the sources of carbon monoxide in the home and how to locate and remove them.

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Carbone Monoxide and it's effects

As firefighters, we already are familiar with carbon monoxide and know it can be deadly on the fireground. It can be just as deadly in the home in a nonfire situation. According to the Journal of the American Medical Association, carbon monoxide is responsible for 800 to 1,000 accidental deaths a year. This makes it the most common cause of unintentional poisoning deaths in the United States. It is estimated that 10,000 people annually seek medical attention as a result of carbon monoxide poisoning.

Carbon monoxide, a colorless, odorless, and tasteless gas, is slightly lighter than air, with a specific gravity of 0.97 and has an explosive range of 12.5 to 74 percent. It is lethal in minutes at 1.28 percent in air and will asphyxiate long before it poses all explosion danger. Measured in the air in parts per million (ppm), carbon monoxide exposure of 800 ppm for 45 minutes can cause flu-like symptoms, while exposure to the same 800 ppm for three hours can cause death.

Inhaled carbon monoxide is absorbed by the oxygen-carrying portion of the blood, hemoglobin. The carbon monoxide and hemoglobin combination is known as "carboxy hemoglobin" (COHb). Carbon monoxide is 240 times more likely to be absorbed by the hemoglobin than oxygen (O&subl2;). As a result, small amounts of carbon monoxide in the air can rapidly increase the COHb level. Carbon monoxide replaces oxygen in the blood, depriving organs and cells of needed oxygen and prevents the release of the oxygen in the blood, further reducing the oxygen available to the body. It is a one-two punch that can be fatal once the COHb level reaches 50 percent to 70 percent. At this elevated level, carbon monoxide causes asphyxiation and death. In fresh air, it takes about five hours to reduce a 10 percent COHb level by half, to five percent - giving it a half-life of five hours in the body's system.

Toxic Effects Of Carbon Monoxide
Carbon
Monoxide
( CO )
( ppm *)
Carbon
Monoxide
( CO ) in air
( percent )
Symptoms
Due
to
Exposure
100 0.01 No symptoms - no damage
200 0.02 Mild headache; few other symptoms
400 0.04 Headache after 1 to 2 hrs
800 0.08 Headache after 45 min.;
nausea, collapse and
unconsciousness after 2 hrs
1,000 0.10 Dangerous - unconsciousness after 1 hr
1,600 0.16 Headache, dizziness, nausea after 20 min.
3,200 0.32 Headache, dizziness, nausea after 5
to 10 min.; unconsciousness
after 30 min.
6,400 0.64 Headache, dizziness, nausea after 1
to 2 min.; unconsciousness
after 10 to 15 min.
12,800 1.28 Immediate unconsciousness;
danger of death in >br>1 to 3 minutes
* Parts Per Million - ratio of the volume of contaminants ( parts)
compared to the volume of air (million parts )

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Treating carbone monoxide poisoning

Remove victims from the contaminated atmosphere and administer 100 percent oxygen through a tight-fitting face mask. The half-life of carbon monoxide in normal air is approximately 300 minutes. Breathing pure oxygen reduces this half-life to 80 minutes, and hyperbaric oxygen further reduces it to 23 minutes. Hyperbaric oxygen, available at selected medical facilities, delivers oxygen at greater then atmospheric pressure. It effectively pushes the carbon monoxide out of the blood. Hyperbaric oxygen should be considered for anyone who has suffered a serious carbon monoxide exposure particularly victims who have lost consciousness as a result of carbon monoxide poisoning, although even a person with less exposure can benefit from it.

Oxygen therapy, by reducing the half-life, reduces the time carbon monoxide has to harm the body and increases the amount of oxygen available in the blood. As first responders, we can administer oxygen on the scene and alert medical authorities to the fact that there may be a need for hyperbaric oxygen. If you don't know the location of the nearest hyperbaric chamber or how to get a patient to one, now is the time to set up a protocol for your department. Delaying this treatment can be deadly.

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Triage of calls for carbone monoxide detector alarm

A call involving a sounding carbon monoxide alarm may be an emergency or a routine response. The deciding factor is whether the structure's occupants are experiencing symptoms. If all alarm is sounding but no one is exhibiting symptoms it is a routine response because the occupants are in no immediate danger. If, however, symptoms are evident, the response becomes an emergency and warrants quick action.

One solution for handling increased carbon oxide responses may be to train dispatchers to triage calls for sounding carbon monoxide alarms. They should determine from the caller whether anyone in the house has symptoms and if everyone is accounted for. They then will be able to adjust the response level to fit the situation. Triaging these calls can reduce your department's workload. A single field unit equipped with a survey instrument would be able to handle a routine response, whereas all emergency response might require several fire and EMS units. The first-arriving unit can change the dispatcher's decision according to the actual conditions encountered.

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Recognizing the symptoms of carbone monoxide poisoning

Carbon monoxide is known as the great imitator because a mild exposure to it can mimic the flu, causing a slight headache, nausea, vomiting, and fatigue. These symptoms often are misdiagnosed by residents as well as doctors in hospital emergency rooms. In one study, almost onefourth of all the patients complaining of flu symptoms in a hospital were actually suffering from carbon monoxide poisoning. One of the ways to distinguish between the symptoms of carbon monoxide poisoning and the flu is to determine whether all the family members or occupants of a building are experiencing the symptoms at the same time. If everyone has the symptoms, suspect carbon monoxide poisoning: the flu usually does not afflict all occupants at the same time.

A medium exposure to carbon monoxide can cause severe headache, drowsiness, confusion, and a fast heart rate. These symptoms might be mistaken for those of substance abuse. The confusion resulting from exposure to carbon monoxide can prevent a victim from leaving a contaminated atmosphere even if the danger is realized.

Extreme exposure will result in unconsciousness convulsions, heart and lung failure, and death.

Carbone monoxide can affect individuals differently even if they have the same COHb levels. One hyperbaric chamber facility reports comatose victims with carbon monoxide levels under five percent. It also reports walking, talking victims with levels of 50 percent. Severe exposure to carbon monoxide can produce long-term neurological effects, whereas chronic low-level exposure is thought to be complicit in causing heart disease to develop. Don't expect to see the so-called classic cherry red coloration of a victim of carbon monoxide poisoning. Doctors who treat carbon monoxide victims say that it is rare. Victims are more likely to appear pale or cyanotic.

Note: The level of exposure, or percent of COHb, used in determining the effects of carbon monoxide were set for healthy adults. The following at-risk groups will experience symptoms of carbon monoxide poisoning before healthy adults.

  • Children. Since they are smaller and have a faster metabolism, they take in carbon monoxide faster than a healthy adult and are adversely affected by lower levels.
  • The elderly.
  • Individuals with preexisting lung, or heart conditions. (Many of the elderly have preexisting heart or lung conditions.)
  • The fetus. Studies have shown that 50 percent of pregnant women who suffer a significant carbon monoxide exposure lose their unborn children. Carbon monoxide builds up slower in the fetus than in the mother but reaches higher levels and remains in the blood longer. Also, fetal hemoglobin has a greater affinity for carbon monoxide than maternal hemoglobin. There is additional concern that a serious fetal exposure could result in malformations or neurological damage should the fetus survive. For these reasons, hyperbaric oxygen should be considered for exposed pregnant women.

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Guidelines for responses

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