Unseen threats are routine for first responders. Knowing whether there is imminent danger is key to getting home safely. This column outlines several cases in which the Chicago, IL, Fire Department (CFD) learned the value of using available technology in gauging an appropriate response. More...
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Unseen threats are routine for first responders. Knowing whether there is imminent danger is key to getting home safely. This column outlines several cases in which the Chicago, IL, Fire Department (CFD) learned the value of using available technology in gauging an appropriate response.
More than 10 years ago, the CFD began deploying single-gas carbon monoxide (CO) monitors on all 200 of its engines and trucks. This came about with the advent of commercially available CO monitors for home use. The early home units often went into false alarm, and this would result in a panicked call from a homeowner for a response from the fire department. The need to know whether there was an immediate threat to life or health could not wait for the arrival of a hazardous material response team. Each engine company was initially equipped with an industrial, single-gas CO monitor. These were most useful in the winter, when CO calls were often due to incomplete combustion in faulty heating systems.
"After a family died from carbon monoxide poisoning 12 years ago, we first deployed single-gas CO sensors on every truck," said Chief Daniel O'Connell, coordinator for CFD Special Operations and Hazardous Materials.
Single-gas CO monitors might still be the norm had it not been for some catastrophic events. In one instance, an engine company arrived for what was thought to be a CO call. Because there was no alarm from the CO monitor, firefighters assumed all was safe and entered the building. One firefighter turned on the building's lights, initiating an explosion from a natural gas leak. "We began investigating the use of four-gas meters … after several 911 calls where the CO monitor was not sufficient to detect the unseen threat, and we had two gas explosions," added O'Connell.
Over a two-year period, the department evaluated different combinations of instruments and sensors. The objective was to determine whether there was an immediate threat to life or health and, if the instrument alarmed, whether it would be sufficient to determine the need to secure the area and notify a hazmat team. The department's two hazmat teams tested various combinations of instruments using four sensors: lower explosive limit (LEL) for combustible materials, CO, hydrogen sulfide (H2S) and oxygen (O2). Each sensor was chosen for the life-critical or time-critical threat information provided if it went into alarm. The CO sensor was already proven. The LEL sensor was selected to detect the presence of high levels of flammable gas. The hydrogen sulfide sensor was chosen because H2S easily saturates a responder's sense of smell. The oxygen sensor was selected because it would immediately indicate the need for an air mask and may also show the presence of an oxidizer. Other sensors that were considered included chlorine and ammonia, but both substances have other characteristics that make them identifiable. Four-gas instruments were evaluated for ruggedness, user interface, calibration stability, battery life and ease of service. "We went through an evaluation process and selected the RAE Systems QRAE. The QRAE adds to the complement of RAE Systems instruments already used by the CFD hazmat teams, including wireless AreaRAE RDK monitors, MultiRAE Plus four-gas monitors with PIDs, ppbRAE PIDs for decontamination and others," said O'Connell.
To gain personnel efficiency, the four-gas instrument calibration team works out of the same division as the breathing-air pack services. "Our in-house technicians maintain our fleet of over 200 QRAE units deployed at 102 firehouses," said Chief Robert Anthony, coordinator of the Chicago Fire Department's Division of Equipment and Supply. "We currently calibrate each unit using the AutoRAE calibration station on a monthly cycle."