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.,

Background: 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 working.

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 continuous monitor. 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 cost effective.Enabled 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]