Six Worcester (Mass.) firefighters died a decade ago during the Cold Storage warehouse fire. Investigators said firefighters were disorientated by smoke-masked hallways, and their bodies were found only a few feet away from an exit. Since the tragedy, scientists have been rigorously testing personal alert safety system, or PASS, devices — which have been around for a quarter century but only recently added wireless communications to better safeguard personnel on the fireground.

Earlier versions of PASS only were required to detect motion, then flash a light and trigger a high-pitched noise if a firefighter stopped moving for 30 seconds. There was widespread adoption after performance standards were established in NFPA 1982. But field-use showed that they often malfunction on the fireground, said a National Institute for Operational Safety and Health report. The report found the alarm signals often were either not heard or were barely audible, apparently due to thermal-related degradation.

Sen. Charles Schumer (D-N.Y.) took notice of PASS device failures, saying in a press release that malfunctioning devices were threatening the lives of thousands of firefighters across New York. Schumer said that over the past decade, 15 firefighters nationwide have died when PASS devices failed under routine heat and water conditions.

“[W]hen firefighters put their lives on the line to save others, their gear must function at the highest standards possible,” he said in the statement. “And when it doesn't, it should be pulled from the market — fast.”

Schumer issued a mandate to investigate and improve PASS devices. As a result of the mandate, researchers at the National Institute of Standards and Technology are studying the next-generation PASS device — one with a wireless component — at the request of the National Fire Protection Association. NIST will set forth device test methods, determine reliability and later release operational best-practices guidelines and industry standards, said Kate Remley, a research scientist at NIST.

“There are few standards available that tell firefighters when and where they can safely deploy these devices; or whether they can count on them to reach from the inside to the outside of a building,” Remley said. “As with every wireless system, the technology won't work in every situation so we are … developing test methods so firefighters will know when they can expect PASS devices to work, and in what situations.”

With wireless, the alarm transmits a signal in near-real-time from the firefighter's SCBA unit or a mobile sensor attached inside turnout gear to an incident commander's wireless laptop located outside a building. Each device acts as a repeater, where one relays a signal to another, and also can be used in a point-to-point configuration, where signals carry from a PASS device to a base station, Remley said.

However, there are issues with the wireless communication system. Signal penetration into buildings and transmission quality can be poor, Remley said. In addition, RF-based emergency equipment has little to no performance standards, and consumer wireless devices are not intended for the rugged conditions encountered by emergency responders.

That's why testing the units to determine when and where radio signals are reliable — as well as standardizing operational best practices — is so important, Remley said. For the system to be worthwhile, it must have a near 100% success rate.

“It's crucial to maintain a radio signal at all times,” Remley said.

Research and Development

Indeed, research institutes continue to develop wireless tracking systems because losing first responders at an incident scene happens more than anyone would like to admit, as evidenced by the Cold Storage warehouse tragedy. However, the tragedy led to more research and development projects, such as those at Polytechnic Institute (WPI), where researchers are building a prototype wireless tracking device, said WPI's Jim Duckworth, co-principle investigator on the project.

The institute was given $3 million by the Department of Justice and National Institute of Justice to develop a firefighter tracking system. In response, WPI developed a commercial system that can pinpoint a person's location in three dimensions to within about a foot and track up to 100 people simultaneously — displaying the position and path of each individual on a laptop or at an incident command center, Duckworth said.

Researchers led by Duckworth and co-principal David Cyganski determined they needed a locator system with transmitters and receiver units. The system they developed consists of hardware and software-defined radio components. Each firefighter wears a small cell phone-sized radio transmitter inside his turnout gear. The transmitter sends a special set of tones from the firefighter through the building's walls and floors to the receiver unit outside the building. The receiver units are designed to be embedded into fire trucks.

“[The system] determines … where exactly the firefighters are in the building and real-time data are sent to the command's computer screen so they can see exactly where all of the staff are at any given time,” Duckworth said.

But the software's capabilities recently were expanded at the request of FEMA, which gave the institute $1 million to integrate location tracking with physiological monitoring. FEMA wanted to reduce incidents of firefighter fatalities due to stress-related heart attacks, so the entire system has been updated to include a physiological monitoring shirt with embedded sensors that pace a firefighter's heart rate. The physiological information is added to location data and mapped out through incident command software.

“On the incident commander screen, we developed a GUI [graphical user interface] map that shows location tracking, as well as the vital signs of each firefighter,” Duckworth said.

Recent incidents emphasize the importance of knowing where fireground personal are at all times, said Jose Vazquez, director of first-responder technologies for the Department of Homeland Security's Science and Technology Directorate, and a beta-tester for the WPI system. Simply put, tracking systems let commanders send search-and-rescue teams directly to a lost firefighter, Vazquez said.

“You need a precise measurement of where firefighters are located in a structure, so commanders can reduce the time to find them,” he said.

Yet current wireless technologies often fail to reliably deliver needed location data because of interference issues. Duckworth said WPI's system tries to minimize the problem by using multi-path transmissions, where a radio transmission transmits in several directions. But he admitted another problem concerns ruggedness, because the prototypes wouldn't hold up in a fire environment.

“Our prototypes are fragile. … We couldn't drop them from a great height and they wouldn't survive high-pressure water at an incident,” he said.

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