Carbon monoxide is a colorless, odorless, tasteless and toxic gas produced
as a by-product of combustion. Any fuel burning appliance, vehicle,
tool or other device has the potential to produce dangerous levels
of carbon monoxide gas. Examples of carbon monoxide producing devices
commonly in use around the home include:
Fuel fired furnaces (non-electric)
Gas water heaters
Fireplaces and woodstoves
Gas stoves
Gas dryers
Charcoal grills
Lawnmowers, snowblowers and other yard equipment
Automobiles
The Consumer Products Safety Commission (CPSC) reports that approximately
200 people per year are killed by accidental CO poisoning with an additional
5000 people injured. These deaths and injuries are typically caused
by improperly used or malfunctioning equipment aggravated by improvements
in building construction which limit the amount of fresh air flowing
in to homes and other structures.
While regular maintenance and inspection of gas burning
equipment in the home can minimize the potential for exposure to
CO gas, the possibility for some type of sudden failure resulting
in a potentially life threatening build up of gas always exists.
Carbon monoxide inhibits the blood's ability to carry oxygen to body tissues
including vital organs such as the heart and brain. When CO is inhaled,
it combines with the oxygen carrying hemoglobin of the blood to form
carboxyhemoglobin. Once combined with the hemoglobin, that hemoglobin
is no longer available for transporting oxygen. How quickly the carboxyhemoglobin
builds up is a factor of the concentration of the gas being inhaled
(measured in parts per million or PPM) and the duration of the exposure.
Compounding the effects of the exposure is the long half-life of carboxyhemoglobin
in the blood. Half-life is a measure of how quickly levels return to
normal. The half-life of carboxyhemoglobin is approximately 5 hours.
This means that for a given exposure level, it will take about 5 hours
for the level of carboxyhemoglobin in the blood to drop to half its
current level after the exposure is terminated.
Since one can't easily measure COHb levels outside
of a medical environment, CO toxicity levels are usually expressed
in airborne concentration levels (PPM) and duration of exposure.
Expressed in this way, symptoms of exposure can be stated as follows:
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PPM CO Time Symptoms
35 PPM 8 hours Maximum exposure allowed by OSHA in
the workplace over an eight hour period.
200 PPM 2-3 hours Mild headache, fatigue, nausea
and dizziness.
400 PPM 1-2 hours Serious headache- other symptoms
intensify. Life threatening after 3 hours.
800 PPM 45 minutes Dizziness, nausea and convulsions.
Unconscious within 2 hours. Death within 2-3 hours.
1600 PPM 20 minutes Headache, dizziness and nausea.
Death within
1 hour.
3200 PPM 5-10 minutes Headache, dizziness and nausea.
Death within 1 hour.
6400 PPM 1-2 minutes Headache, dizziness and nausea.
Death within
25-30 minutes.
12,800 PPM 1-3 minutes Death.
As can be seen from the above information, the symptoms
vary widely based on exposure level, duration and the general health
and age on an individual. Also note the one recurrent theme that
is most significant in the recognition of carbon monoxide poisoning-
headache, dizziness and nausea. These 'flu like' symptoms are often
mistaken for a real case of the flu and can result in delayed or
misdiagnosed treatment. When experienced in conjunction with a
the sounding of a carbon monoxide these symptoms are the best indicator
that a potentially serious buildup of carbon monoxide exists. This
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