Carbon Monoxide (CO) Measurement and Dosimetry for Fire Fighters
J. R. Stetter, Ph.D.
Professor of Chemistry, Illinois Institute of Technology and President, Transducer Technology, Inc.,
Fire Fighters are often well equipped and well trained. They arrive at a fire and setup
a command post in a safe-zone, have gear to protect them from the
fire, and gear to combat the fire. Personal protection from smoke particles and gases is available by using
Self-contained Breathing Apparatus, but this impedes physical activity
and makes fighting the fire more difficult. Masks that are full, or offer partial face coverage, are
sometimes used. These masks can contain filters for particulates
[smoke] and possibly charcoal canisters for protection against organic
fumes. Neither of these, however, remove carbon monoxide, CO, and thus
exposure to carbon monoxide remains a concern for firemen.
Existing monitors for CO are effective at measurement of the concentration in the area
where they are placed, but cannot follow the fireman where he is
Exposure to Carbon Monoxide:
Current safety standards vary from agency to agency, but the most conservative agency
is the American Conference of Governmental and Industrial Hygienists [www.ACGIH.org].
The new ACGIH 2004 guidelines list the TLV/TWA for CO at 25 ppm, i.e.,
25 ppm for 8 hours, and do not offer the usual ceiling value of 400
ppm [used by OSHA]. Instead of a ceiling value, ACGIH guidelines give
a maximum exposure of 3 to 5 times the TLV, explained as: the maximum exposure for 30 minutes should not exceed 3 times
the TLV, and one should never be exposed to more than 5 times the TLV.
Putting this into practice for Carbon Monoxide, would limit exposures
to a maximum of 75 ppm for 30 minutes and set a never to exceed
ceiling value of 125 ppm CO.One more indicator is the BEI, or Biological Exposure indices. The CO that
is inhaled is bound to the hemoglobin in the red blood cells making
them incapable of carrying oxygen. Therefore, CO exposure causes a
type of anemia and symptoms are like asphyxiation, with dizziness,
drowsiness, nausea to the degree of the insult suffered. The CO poison is in equilibrium in the lungs, and a person with
3.5% COHb [3.5% poisoning of the hemoglobin] will emit about 20 ppm CO
in the exhaled lung alveolar air. It takes about 8 hours breathing CO free, clean air to clear
one half of the CO poisoning from a person, i.e. go from 3.5% to 1.75%
CoHb. If you measure the lung air, and it reads 20 ppm in the end tidal breath air, it could
mean CO exposure, but there are other exposures beyond workplace
exposure that could lead to CO on the breath, not the least of which
is cigarette smoking.
In conclusion, it is important for the health and operational effectiveness of a fire
fighter that he/she is not over-exposed to CO, and if exposed, the
person is allowed to go to a clean space and breath clean air to
detoxify. Critical in this identification of toxification is a
reliable method of measurement for CO exposure.
Methods of CO Detection:
What type of methods and instruments can be used to assess carbon monoxide hazards in and
around the fire fighters’s workplace?
From an operational point of view, the safe place or
headquarters for the fire fighting team needs to be a location at a
safe distance downwind from the fire, where the CO hazard is minimal.
Direct reading instruments can be used to measure the CO in the air
near the safe house, but a continuous monitor would be better. If the wind shifts, this change would be incorporated in a
The worker can be monitored with either a personal dosimeter or alarm. Some CO devices
are simple alarms that ring or buzz when exposures are high. The
measurement of the concentration in the breathing zone of the fire
fighter would be ideal to measure, but in this case the detector needs
to be very small and lightweight. A new instrument, Transducer Technology, Inc.’s, “Pocket
CO”, continuously monitors CO and also performs dosimetry, i.e.
calculates the total exposure [ppm-hours] and the TWA/TLV [ppm]. It outperforms available monitors, and is small enough to be
easily worn on the lapel, hard hat, or shirt pocket.
The monitoring of workers in and around radiation hazards has been performed for many
years. The idea is simple. Upon entry into the area where the
hazardous exposure may occur, a person who may suffer the exposure is
handed a badge which is clipped to an outer garment. When said worker is exiting this area, the badge is put into a
reader which then reports the total exposure received. In an analogous manner, TTI’s “Pocket CO” [less
than 1 ounce], can be set up in an 8-hr mode and clipped to the
person’s outer garment or equipment. After return from exposure, a
push of a button retrieves the total exposure in ppm-hours and the TWA/TLV
in ppm, as well as the maximum concentration recorded and time of its
occurrence during the monitoring period. Based on the “Pocket CO’s” information, the person
can be sent for COHb measurement to determine biological dose or
return to work.
Conclusion:The “Pocket CO” is the newest tool available to improve the
safety of the firefighter’s workspace, and the smallest and most
by advances in both materials and nanotechnology, the innovative
“Pocket CO” has features heretofore only available in cumbersome,
expensive instruments. The tiny instrument can be worn by individuals
or placed on the doorway or entrance to the safe place, in and around
a fire. The
“PocketCO” will monitor CO exposure, alarming if and when it
occurs.It simultaneously provides further benefits as a CO dosimeter
to minimize, mitigate, and manage personal exposure on the job.
The new “Pocket CO” is a pocket
sized, low cost CO-monitor, alarm, and dosimeter.Features include
temperature compensation, sensor accuracy of the fixed site
instruments, and internal battery life of one year or more guaranteed.A single push
button makes it easy to use for spot checking areas or for CO
dosimetry or for data retrieval. The “Pocket CO” is a Carbon
Monoxide measurement tool in your hand or pocket, always ready to go
when and where you are. [see www.transducertech.com]