Unseen threats are the routine for first responders. Knowing if there is imminent danger is key to getting home safely. This article outlines several cases where the Chicago Fire Department learned the value of using available technology in gauging an appropriate response.
More than 10 years ago, the Chicago Fire Department began deploying single-gas CO (carbon monoxide) 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 if there was an immediate threat to life or health could not wait for the arrival of the 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 Chicago Fire Department (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 they thought was a CO call, and because there was no alarm from the CO monitor, they assumed all was safe and entered the building. One of the firefighters turned on the building’s lights, initiating what turned out to be an explosion from a natural gas leak. “We began investigating the use of 4-gas meters two years ago, 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 this two-year period, the department ran various evaluations on different combinations of instruments and sensors. The objective was to determine if 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 the HazMat team. The department’s two HazMat teams ran experiments using various combinations of instruments using the following four sensors: lower explosive limit (LEL) for combustible materials, carbon monoxide (CO), hydrogen sulfide (H2S) and oxygen (O2). Each of the sensors was chosen for the life-critical or time-critical threat information provided if it went into alarm. The carbon monoxide sensor was already proven. The lower explosive limit sensor was selected to detect the presence of high levels of flammable gas. The hydrogen sulfide sensor was chosen because H2S is a common threat that 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 might 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 from many manufacturers 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 utilized by the CFD HazMat teams, including wireless AreaRAE RDK monitors, MultiRAE Plus 4-gas monitors with PIDs, ppbRAE PIDs for decontamination and others,” said O’Connell.