Emerging Technologies: Aiding Responders in Mine Emergencies and During the 

Escape from Smoke-Filled Passageways 

Ronald S. Conti 

National Institute for Occupational Safety and Health 

P.O. Box 18070, Pittsburgh, PA 15236 

rkc4@cdc.gov
 

ABSTRACT 

Historically, underground mine rescue teams have received training only in the course of actual 

emergencies, or in simulated mine environments, usually on the surface, with placards to identify 

objects and hazards. Also, while U.S. Federal Regulations require all underground miners to walk 

escapeways and conduct fire drills every 90 days, this does not fully prepare them for the conditions 

that may be encountered in real escape situations, such as smoke filled entries. This paper describes 

technology and realistic training simulations that have been identified for the general workforce and 

mine emergency responders. Of all the technology evaluated by underground personnel, laser lights 

and lifelines were most beneficial in leading personnel to safety and out of the mine in smoke-filled 

passageways. These technological advancements can improve the state of readiness for rescue 

personnel and increase the chances of survival for personnel escaping from underground emergencies. 

INTRODUCTION 

Mine rescue teams are often called upon to save lives during an underground emergency such as a 

fire, explosion, roof fall, or water inundation. It is extremely important that team members are 

provided with adequate exploration and recovery equipment and be properly trained in the use of that 

equipment. Over the past several years, the National Institute for Occupational Safety and Health 

(NIOSH) Pittsburgh Research Laboratory (PRL), in collaboration with state agencies and several 

mining companies, has developed, conducted and evaluated mine rescue training simulations, in-mine 

smoke training exercises, and mine emergency response drills (MERD) at its Lake Lynn Laboratory 

(LLL) near Fairchance, PA and operating mines. These training simulations allowed rescue personnel 

to train under realistic conditions and focused on fire fighting, ventilation, searching for “victims”, 

first aid, mapping, etc. (Conti, et al.1998). 

The research efforts have resulted in improved disaster recovery training drills for mine rescue 

teams, fire brigades, first responders, and miners in general and the development of new technology 

such as new team lifelines and inflatable devices for fire suppression and personnel escape (Weiss, et 

al.1996; Conti and Weiss 1998; Kennedy, et al. 1991). Existing technologies were identified to help 

responders during exploration and recovery operations. These included various chemical light 

shapes, strobe lights, light vests, and laser pointers to identify team members. Most of these devices 

may be used to mark underground areas and certain mine materials. Also, strobe lights were used for 

mapping out escapeways and lasers were used to negotiate travel through smoke. Thermal imaging 

systems allow rescue personnel to see in darkness and through dense smoke and easily locate missing 

or trapped personnel and heated areas. A hands-free communication system showed potential for 

enhanced communications between team members, the fresh air base, and command center. 
 

 

This paper focuses on the importance of early warning to alert all underground personnel of an 

emergency event and looks at devices that may assist personnel during their escape from smoke-filled 

passageways. The various technological devices used by the emergency responders during the 

training simulations are discussed. It concentrates on technology that can assist responders during 

exploration and recovery operations (Conti, et al. 1999). For example, through the earth signaling 

and effective communications, identifying personnel and materials in smoke, lifelines for escape, 

vision enhancement and inflatable devices. 

THROUGH THE EARTH SIGNALING AND COMMUNICATIONS 

 It is imperative during an underground emergency that all personnel, no matter where their 

location is, can be notified of the event. The LLL has installed such a device, a wireless signaling 

system that transmits an emergency warning, which can quickly reach every underground miner. The 

low-frequency electromagnetic field can penetrate kilometers of soil and rock to reach the most 

remote shaft or tunnel, which makes it ideal for underground signaling and paging. This system 

consists of a low-frequency transmitter that can be strategically placed to create an electromagnetic 

signal that can completely envelop most mines without the use of repeater systems. The transmitter 

loop antenna is on the surface, and a receiver/transmitter loop antenna is underground. The personwearable receivers are small, lightweight modules incorporated into the miner's cap lamp assembly. 

Signals can be directed to an individual, to a group, or to all underground/surface personnel. Fire 

brigades and mine rescue teams could be alerted, and key personnel contacted. Upon receiving an 

emergency or paging signal, the cap lamp begins to flash, which in turn alerts the miner to evacuate 

the mine or call the surface for a message, depending on which signal is received. The system can 

also turn devices such as strobe lights on or off to identify escape routes. Additional information on 

wireless signaling systems and medium frequency radio communication systems for mine rescue can 

be found in (Conti and Yewen 1997; Dobroski and Stolarczyk 1982). 

A successful evacuation of miners during the Willow Creek mine fire, that occurred in Helper, 

Utah, on November 25, 1998, was attributed to a similar system, the Personal Emergency Device 

(PED)1

1

 Mention of any company name or product does not constitute endorsement by the National Institute for 

Occupational Safety and Health 

 (Zamel 1990). This system displays a message on a LCD display after the cap lamp flashes. 

The paging system was activated when one miner saw flames and telephoned the dispatcher to 

evacuate the mine. The PED system allowed a mine-evacuation plan to be safely carried out before 

the mine passageways filled with smoke. All 46 underground miners escaped in approximately 

45 minutes. There are currently 17 PED systems installed in U.S. coalmines and one in a 

metal/nonmetal mine. 

Transtek Corp has developed a wireless, two-way cellular communications system for 

underground mines (Product and Process News). The ComCell technology can be used to reduce 

communications costs and improve underground productivity. They are also testing a unique 

Through the Earth wireless system that allows two-way mobile voice and data communications 

between the underground passageways and above ground sites. There are currently 2 systems 

installed in underground facilities. 

Communication is a major issue and concern of rescue teams. Team members are often unable to 

hear other members, and at times the communication signal to the fresh air base is also faulty. This 
 

 

 

 

can be very frustrating to team members, especially in high stress situations. The sound powered 

communication/lifeline system, developed in 1946 by the former U.S. Bureau of Mines, is the most 

typical system in use today. Although this type of system tends to be reliable, it does have problems. 

It requires the use of large cable reels (304-m of cable) and the communication often gets scrambled 

as the electrical contacts in the cable reel wear. Also, good electrical connection to and along the 

lifeline cable is necessary. The current practice is that the tail person, who has the earphones and 

microphone, talks to the fresh air base. 

To address the communication concerns of mine rescue teams, several devices and systems were 

looked into (Conti and Chasko 2000). For example the m-Comm communications system, developed 

in the United Kingdom, shows merit for improved communications for emergency responders. This 

system is intrinsically safe and designed specifically for confined space and rescue applications. It 

consists of a single (lightweight) wire on a dispenser reel holder, that is payed out on entering the area 

to be explored, three handsets, and a portable base unit. The handsets receive and transmit from any 

point along the guide wire. It has a range of 8-Km and the guide wire could be deployed from the 

fresh air base to the surface command center. 

Other devices such as the Voiceducer and or “head-contact microphone” maybe used if the mine 

had a radiating transmission line or if the lifeline was also antenna. The Voiceducer, combined with a 

two-way radio, provides hands free two-way communications from a small device worn in the ear. 

Although it looks like an ordinary earphone, the earpiece contains both an accelerometer microphone 

and a miniature receiver component. The “head-contact microphone” is a hands-free radio 

microphone that can either be strapped onto the forehead or incorporated into a helmet headband. 

Rescue members need not to speak into this microphone; it gathers sounds from vibrations 

transmitted through the skull and works whether the rescue member is wearing an SCBA or not. 

Additional research is underway to improve mine rescue communications. 

IDENTIFYING PERSONNEL, MATERIALS AND ESCAPE ROUTES 

Figure 1. Chemical lightsticks 

attached to the back of miners.

NIOSH attempted to address several issues raised by rescue team members that participated in the 

simulations. One of the main concerns of the rescue teams was identifying other team members and 

marking locations, such as crosscuts, brattice curtain, 

cribbing, and other items that may be found in the smokefilled entries, or just maintaining a reference point. Chemical 

lightshapes (lightstick, light rope and light disc), a 

technology that has been around for years, were found to be 

a valuable tool for underground rescue teams. The 

lightshapes are nonflammable and not a source of ignition, 

and they are weatherproof, maintenance free, and nontoxic. 

To activate, just remove a lightshape from the package, bend, 

snap, and shake. Instantly, a source of light exists that can 

vary in intensity and duration. The brightest lightstick lasts 

5-min and the least brightest, 12-hrs. The brightest lightstick 

is an excellent source of light to administer first aid in smoky 

environments. Team members assessed the cylindrical 

lightsticks during the simulations, both in white nontoxic 

smoke and black toxic smoke produced from conveyor-belt 
fires. Four lightstick colors were evaluated; clear, green, red, and yellow. Team members, as shown 

in figure 1, attached these lightsticks to the back of their helmets with plastic ties. They can be also 

placed on the floor at various critical locations and on obstacles during exploration or may be used to 

mark supplies and materials. The team member, whose duties require mapping the passageways, can 

use a lightstick to illuminate the map board. Of 403 members participating in the white nontoxic 

smoke training simulations, 80 pct-identified green as the most dominant color seen and the least 

visible color was clear. Out of the 90 rescue team members that participated in fighting the conveyorbelt fire, 85 pct felt that green was the most dominant color; red was the least visible color. 

Lightsticks are an important component for some mine rescue teams. 

Team members also evaluated other lightshapes. Lightropes were mounted around the brim of the 

helmet, and circular lightdiscs were mounted on the back of the self-contained breathing-apparatuses 

(SCBA’s). The lightdisc was helpful, however, the lightrope was found to be ineffective. 

In other smoke training exercises, the lightstick was effectively used to negotiate travel through a 

smoke-filled passageway. The participants turned off their caplamp and held a green lightstick out in 

front of them, about waist high. Some miners have started storing lightsticks in their lunch buckets or 

having them in their possession for emergency use. 

Personnel working around moving equipment in low light areas are always placed at risk due to 

their poor visibility to the operator. The light vest is a technology, developed by LiveWire 

Enterprises, Inc., that uses a blue/green or orange electroluminescent fiber and a 0.5-mm copper wire 

coated with a semiconductor material. It is safe, non-toxic, flexible, impact and water resistant, 

portable and produces no heat. An AC or DC power source is used depending upon its length; and 

current consumption is as low as 0.3 mA/m. Two AA batteries could power the vest for over 24-hrs. 

The light vests were modified with Velcro straps to wrap around a mine rescue member, including 

their SCBA, for 360 degree visibility. Team members felt that it was much easier to see other team 

members, who were wearing the light vest, in darkness and in smoky entries. Several mines are also 

considering the use of light vests for personnel working around moving machinery. 

Another area examined was utilizing high-intensity strobe lights (xenon-white flash tube) 

strategically located in the entries to map out an escape route for evacuating miners during an 

emergency. They were also used to mark materials (fire hydrants, cribbing, etc.) in the smoky 

passageways. These weather resistant strobe lights, with interchangeable reflective lenses, are 

compact and lightweight and provide visibility of 180°. The triangular shaped, lithium AA battery 

powered strobe lights could be remotely activated by a wireless through-the-earth signaling system 

such as the one installed at LLL. Ideally, underground sensors would monitor the gases and smoke in 

the passageways during a fire. By interfacing these data with a computer, the best escape route could 

be determined and the appropriate strobe lights remotely turned on. 

During in-mine rescue team simulations conducted at LLL, strobe lights were positioned in the 

center of the entry about 1.8-m from the floor and in the entry crosscuts predetermined to be the best 

escape routes. The strobe lights were activated by the wireless, through the earth signaling system. 

Rescue team members were told that a roof fall had occurred and severed the main 

communication/lifeline. Team members detached themselves from the main communication/lifeline 

and successfully followed the strobe lights out of the smoke-filled entries to the fresh air base. Team 

members felt that by keeping their cap lamps off, the strobe lights were easier to follow. Two 

hundred and seventy-one miners evaluated five strobe light colors (red, green, blue, amber, and clear) 

during the simulations. The most visible color in the nontoxic white smoke was green and the least 

visible color was amber. 
 

A similar simulation was conducted for underground mine personnel in a Western mine. Miners, 

in groups of five, entered smoke-filled (nontoxic white smoke) passageways and followed strobe 

lights to the fresh air base. Not only did this exercise allow miners to travel through smoke in their 

mine (many for the very first time), but also it gave them an opportunity to evaluate the strobe lights 

as an escape aid. Miners felt that placement of strobe lights at decision points was quite helpful and 

interfacing these devices with an audio output would enhance the use of strobe lights for mapping 

escapeways. The miners felt that the colored reflectors currently mounted in the center of their 

entries would not have helped them. 

The concept of strobe lights to identify escapeways and marking mine obstacles was successful in 

experiments at the Lake Lynn Mine and several isolated passageways of a Western mine. In a larger 

mine, the uncertainties inherent in a complex ventilation system would complicate this process 

considerably. Additional research would be required to evaluate the feasibility of using these devices 

in larger mines and incorporating audio output with each strobe light unit. 

Another successful device that was evaluated in smoky environments uses laser technology. 

Commercial laser pointers are compact, lightweight, affordable, and have high quality beams. They 

utilize laser diode technology and several of these handheld battery powered pointers have ranges of 

up to 732-m. Rescue team members’ evaluated two class IIIa laser pointers, red and green. The red 

laser pointer, with a wavelength of 645 nm and output power of 3-5 mW, can operate continuously 

for 8 hours. The green laser pointer, with a wavelength of 532 nm and an output power of 1-3 mW, 

can operate continuously for 2-3 hours. The green wavelength appears brightest to the eye, so a high 

power is not required. Beam diameters are less than 1-mm. 

The team captain is fitted with the green laser and the tailperson with the red laser. These pointers 

are mounted to their cap lamps with hose clamps. The laser beams were highly effective in the 

smoke-filled entries, allowing team members to easily determine the location of the captain and 

tailperson and to stay in better alignment across the entry during exploration. 

During smoke training exercises, the laser pointer was effectively used to negotiate travel through 

a smoke-filled passageway. Approximately 25 participants during each exercise traveled 300-m in a 

nontoxic smoke-filled entry, using a lifeline to lead them to fresh air. Visibility ranged from 0.3 to 

0.9-m and there were no tripping hazards in the entry. Two to three participants entered the smoky 

entry at 40 to 60-sec intervals, until all participants were headed toward the fresh air base. Another 

participant followed this group with only the laser pointer to direct them to the other end (no lifeline) 

and with their cap lamp turned off. The beam of the laser pointer was continuously moved up and 

down and left to right. When the beam hit the rib, roof, floor, or other participants, a spot was seen. 

The participant with the laser reached the fresh air base at the same time as the first participant who 

entered the smoke. The concept of laser pointers was successful in experiments at the LLL and 

operating mines. Additional research would be required to evaluate the feasibility of using higher 

power lasers to identify escape routes in smoke-filled entries or surface structures. 

Everyone realizes the problem encountered while driving an automobile in foggy conditions at 

night with high beam headlights on. The same problem is experienced in smoke-filled passageways 

both by miners attempting to escape and also by rescue personnel. During several training 

simulations in nontoxic smoke, a colored lens filter was placed over the cap lamps of 121 miners in 

an attempt to reduce the glare from the white light reflecting off the smoke particles. The color filters 

that were evaluated included green, blue, orange, and red. Green was the most visible color seen by 

38 pct of the miners. Seventy-one pct of the miners felt the lens filters were useful in reducing the 

glare from the white light and beneficial in traveling through smoke. It has also been suggested that a 
 

miners cap lamp can be taken off the helmet and held about waist high to negotiate travel through 

smoke. 

LINKLINES AND LIFELINES 

Figure 2. Continuous lifeline for 

escape. 

When searching for missing personnel or exploring a hazardous smoke-filled environment in 

underground mines, rescue team members are attached to a team lifeline or linkline. This team 

lifeline is then connected to the main communication/lifeline that extends from the team lifeline to the 

fresh air base. Usually, five team members are fixed along the 8.5-m length of rope, at various 

distances between the captain (lead person) and tail-person. Team members have reported that if one 

person would trip and fall, other team members would be pulled down with the falling team member. 

If the rope became entangled around obstacles, finding it was difficult. 

These concerns were solved by the development of a lighted team lifeline (Conti and Chasko 

2000). Four different colored flexible light wires (Live Wire technology, 0.5-mm copper wire coated 

with semiconductor material) connected in series, pass through a 0.6.4-mm diameter hollow-single 

braided polypropylene rope (336 kg tensile strength) and has 360-degree visibility. The light wire is 

battery powered and will last a minimum of 4-hrs. The entire length of the braided rope is sheathed 

with clear polyvinyl chloride tubing. Double-locking snaps and D-shaped carabineers are attached to 

both ends of the rope for the captain and tailperson, with three moveable snaps and carabineers inbetween both ends for the remaining team members. Team members attach the carabineers to their 

mine belt and have freedom of movement to slide between the captain and tail-person, providing 

flexibility of motion to do activities such as carry supplies, erect temporary ventilation controls and 

construct roof supports. This also alleviates tripping and falling problems. The different colored light 

wires allow the team members to easily find their usual position along the lifeline when exploring in 

darkness and smoke-filled passageways. 

Typically, during exploration at underground intersections in smoky conditions, the tailperson is 

anchored to a corner of a crosscut, while the team members explore the intersection and the captain 

locates the opposite corner. Most of the time, the team is 

restricted by the length of the 8.5-m linkline, and would 

swing back around to the tailperson, missing the opposite 

corner and causing delays. During the training simulation, 

two of the rescue teams evaluated the use of a retractable 

line (6.1-m in length) in addition to the linkline. This new 

concept greatly reduced the time that team members 

explored the intersection, because the captain is able to add 

extra length to the linkline during exploration in 

intersections. 

Underground mines mark their escapeways with 

reflectors or arrows. Usually two colors are used to 

represent primary and secondary escapeways. After a 

period of time, the dust entrained in the airways can collect 

on the reflectors and decrease their effectiveness, so they may never be seen if the passageways are 

filled with smoke. A few underground mines use a continuous lifeline for escape purposes. This 

lifeline or rope would most likely be secured to the rib of the mine starting at the working section and 

leading to the exiting portal. Some mines are securing the lifeline near the roof in the center of the 
entry, at an average height of 2-m from the floor, and lower in lower seam mines. Depending on the 

configuration of the mine, the lifeline could be many kilometers in length. One manufacturer 

developed a directional lifeline shown in figure 2. It consists of standard spools containing 91-m of 

0.64-cm polypropylene rope with directional (cone-shaped) orange indicators with green reflective 

tape installed at every 23-m interval. The tapered end of the cone should always point inby, so that 

escaping miners would never have to take their hand off the line. Due to the complexity of mine 

entries that contain crosscuts, mandoors, overcasts, etc., it is suggested that two directional indicators 

be mounted together on the lifeline approximately 2 to 3-m from a mandoor, etc. This procedure 

would alert personnel escaping in smoke-filled entries that an obstacle of some sort is nearby. 

A study is currently underway to evaluate the feasibility of using prototype pinwheels to identify 

primary and secondary escapeways. The pinwheels are 

constructed from durable and highly reflective Scotchlite or 

Holographic prism materials. The four colors used, shown 

in figure 3, are green (Scotchlite), silver, yellow and red 

(Holographic prism). One side of the pinwheel facing the 

airflow is painted black. During the six-month evaluation in 

an eastern coal mine, data will be collected on dust buildup, 

reflectance to camp lamps and general views from the 

miners on preferred color, etc. 

Figure 3. Prototype pinwheels to 

identify escapeways. 

miners from each section stay together an

evacuation. A few mines have evacuation or escape kits on each section. An ideal kit would contain 

the following items: rope, lightsticks, chalk, SCSR’s, first aid kit, brattice curtain, a mine map, 

handheld gas sensor and, depending on the mine communication system, an extra radio or pager 

phone. The rope is used for the crew to attach themselves to and keep everyone together, especially 

when traveling through smoky passageways. Various colored and intensity chemical lightsticks 

would be available to mark passageways, so if the crew did become disoriented and lost they would 

know that they had passed this way before. They can also be used as a light source to negotiate travel 

through smoke or the high intensity lightstick can be used when administering first aid. Chalk maybe 

used to mark the ribs, stoppings, etc. (names, direction, date and time). Each miner would carry extra 

SCSR’s. A handheld gas sensor can alert the crew of hazardous gases. A pager phone or radio may 

be used to effectively communicate to the surface or rescue team where the crew is located or 

underground conditions. An updated map is essential to travel out of the section and mine to safety. 

Some kits also contain materials to barricade and should only be used as a last resort when all escape 

routes are blocked. Some mines are considering portable lasers to travel through smoke. 

When smoke is encountered underground, visibility is 

reduced, anxiety levels increase and decision making skills 

can become clouded. It is extremely important that the 

d retain the necessary tools to aid them in a successful 

SEEING THROUGH THE SMOKE 

Fire fighting and similar emergency response activities often impair vision due to dense smoke or 

darkness. Vision enhancement in such circumstances is a profound benefit for completing the 

assigned task. Infrared (IR) thermal imaging enhances the user’s vision when visible light is 

inadequate. Thermal imaging both restores vision and also provides significant additional 

information to the user that would otherwise not be possible to obtain, for example, fire scene 
 

 

assessments and seeing through smoke. This technology increases the responder’s understanding of 

the environment (fire location, problem areas like ceiling collapse, firefighters’ progress in effective 

extinguishment, and firefighter safety), thus enhancing safety and the ability to accomplish the task. 

The thermal imaging camera was developed in the early 1970's. Over the last decade, the thermal 

imaging camera has become an invaluable tool for emergency responders and fire assessment. It is 

very different than the common night vision device that either amplifies available light or senses 

reflected near IR energy. Thermal imaging cameras utilize infrared detectors that incorporate special 

materials that provide an electronic signal proportional to the amount of detected radiant energy. The 

latest technology being used is a non-contact sensor called a “micro-bolometer.” The bolometer is a 

device that actually changes temperature proportional to the amount of radiant energy focused on the 

element. This change in temperature generates an electrical signal which when processed produces 

the infrared image that is seen in the viewfinder. The camera differentiates objects by their thermal 

temperature characteristics, and it can see through smoke, darkness and invisible flames produced by 

burning hydrogen or alcohol. However, it cannot see through solid objects, such as concrete and 

masonry, nor can it see someone directly behind the flames. Shiny surfaces (bodies of water, glass, 

stainless steel) reflect IR just as they reflect visible light. 

Recent improvements in the sensitivity and resolution of uncooled IR imaging sensors have 

provided the major enabling technology for the development of a practical helmet-mounted IR vision 

system (Miller 1997). In 1995, Cairns & Brother Inc. introduced the first commercially available 

hands-free helmet-mounted IR imaging systems. Firefighters can use the Cairns IRIS to see through 

dense smoke and darkness in structural fires allowing a faster and more effective “size-up” of the 

situation. The system processes the signal and displays a black and white image that shows the 

hottest areas as white, the coldest as black and the temperatures between as varying shades of gray. It 

can detect 0.3 °C differences in temperatures. The sensor is a specially coated 15-mm Germanium 

lens that filters out everything except 8 to14-micron infrared radiation. The helmet-mounted IR 

imaging system weighs 4.8 kg. A rechargeable nickel cadmium battery pack provides 30-min of 

continuous, uninterrupted use at ambient temperature. 

The first demonstration of the Cairns IRIS in an underground mine was conducted at Lake Lynn 

Laboratory on February 8, 1996 (Conti et al.1998). The capabilities of the hands-free thermal imaging 

camera in the smoke-filled mine passageways suggested that it indeed had merit for reducing the time 

required for mine rescue exploration. However, the training simulations indicated that new protocols 

need to be developed when mine rescue teams explore with these IR devices, because the team 

member with the thermal imaging camera (TIC) can travel smoke-filled entries much more rapidly 

than other team members (Conti et al.1999). One recommendation would be to have a retractable line 

attached to the person using the TIC. This way, the rescue team can still go about exploring and 

mapping, while the member with the TIC, still attached to the team, can examine the thermal image 

more closely and report to the team. A drawback of the Cairns Iris is the weight of the helmetmounted system; the system cannot easily be passed on to other team members and could not be used 

in low coal mine seams. Cairns IRIS recently introduced the Cairns-Viper, a hand-held thermal 

imager. It offers superior image quality, and the innovative, 180-degree-rotating display provides 

comfortable viewing from any position. It enables the user to see from 0.9-m to infinity. 

The Agema 550 System is a high-performance handheld IR camera. It has digital voice 

recordings, color images, and storage capabilities. The spectral range is 3.6 to 5.0-microns and it 

weighs 2 kg. It can easily be passed on to other team members or a small display can be added to the 

camera for all team members to view. The major advantage is that the thermal image can be 
downloaded to a computer for analysis or interfaced directly to a monitor for debriefing members at 

the fresh air base or command center so that key personnel can view thermal images of the event. IR 

cameras may also be used for preventative measures, such as to fire boss underground areas prone to 

fires, for example, belt drives, power centers and areas susceptible to spontaneous combustion. They 

also could be used to monitor welding and cutting operations. 

A Flir System called FireFLIR, is used in conjunction with SCBA’s (other TIC’s can also be used 

this way) and is easily attached to the underside brim of most standard firefighting helmets for handsfree operations. It is a completely self-contained viewing apparatus with no external cables or 

components to catch or to impair movement. The spectral range is 8 to14-microns. The device 

weighs less than 2 kg and images can be viewed in either black and white or color. Advanced optics 

and display offer natural depth perception and orientation. It is also designed to easily view both IR 

and normal visual modes without moving the TIC. The FireFLIR is quickly and easily handed off to 

other team members. Rescue teams that had an opportunity to evaluate the various thermal imaging 

cameras during training simulations preferred this TIC, due to it’s light weight, viewing and carrying 

capabilities and ease in transfer to other team members. 

The Argus Thermal Imaging Camera can also see through smoke and darkness. Its spectral range 

is 8 to14-microns. It is ergonomically designed for comfort and utility, is handheld, and has an 

angled viewfinder. Moreover, this TIC accommodates a variety of users' positions from standing to 

lying prone. In low coal exploration, the innovative design reduces potential neck strain and, when 

used in a stooping position, helps to prevent the back of the 

helmet from hitting the SCBA, which can occur with the 

helmet-mounted version. It can easily be passed on to other 

team members for viewing the thermal image. Argus recently 

introduced the next generation camera (Evolution 4000), shown 

in figure 4. It features a remote wireless video transmission 

system, high-definition big screen display and a heat seeker 

indicator system. The heat seeker displays red attributes on the 

black-and-white display for immediate identification of the seat 

of the fire when the temperature reaches 200 °C. 

Figure 4. Rescue team member 

using a thermal imaging camera. 

During experimental tests at LLL, the video signal from 

the camera was successfully transmitted from inside a metal 

and concrete block fire gallery to an outside remote receiver 

station. The remote receiver, located 60-m away, was 

positioned in the direct line of sight to the camera. In the underground tests, the video signal was 

transmitted from the exploring mine rescue team to the fresh air base (FAB). The remote receiver, 

located 200-m away, was in the direct line of sight with the camera. Command center or fresh air 

base personnel could use this feature to better direct rescue and firefighting efforts. 

During advanced training exercises, mine rescue teams and fire brigade members used a TIC 

during a training application while extinguishing a conveyor-belt fire in the Lake Lynn fire gallery. 

The rollback smoke was so thick and sooty that as the team members entered the fire gallery they 

could not see their hands in front of their facepiece. The person using the TIC was able to view the 

flaming belt, the hot rollback smoke and gases at the roof, and the team members as they entered the 

gallery. This person was in a better position to direct the firefighting efforts of the team. When two 

waterhoses were activated in the fog stream, the water spray immediately cooled the area, thus 
allowing the teams to manage the rollback smoke as they advanced towards the fire to extinguish the 

flames. 

Drager recently introduced the next generation FireOpTIC. This camera features color image 

display, instant on (30-sec for camera to begin normal operation) and remote wireless video 

transmission. Its spectral range is 8 to14-microns. The optional Life Sensor Software allows the 

operator to locate persons who may be near flames without the occurrence of “white-outs” or “blackout borders” on the display caused by viewing open flames. The automatic shutdown feature 

prevents unnecessary and distracting temperatures (above 104 °C) from being read and displayed thus 

allowing the operator to search for bodies based upon their temperatures 

Seeing through infrared cameras is different than with natural vision. IR images are thermal 

interpretations of objects and those interpretations do not appear the same as the objects appear when 

you look at them with the naked eye. It is imperative that personnel using these devices be properly 

trained. 

UNDERGROUND SMOKE TRAINING EXERCISE 

 To better prepare miners to escape from underground smoke-filled environments, a series of 

smoke training exercises were developed and evaluated by NIOSH. Objectives of the exercises were 

to evaluate present escape methods, existing technology, and new technology that could be used for 

escape purposes, while giving the miners an opportunity to travel through smoke-filled entries at their 

mine. A non-toxic smoke generator is used to create a smoky atmosphere and the visibility can be 

varied from several meters to zero. The smoke generator is also an excellent device to evaluate the 

smoke leakage of mine stoppings and seals or to observe air currents. At the end of each training 

segment, miners completed a questionnaire, which included both forced-choice and open-ended 

questions, such as demographics (age, mining experiences, special training, etc), anxiety levels, 

usefulness of the exercise and technology, most visible colors seen in smoke, and underground 

firefighting experience. 

 One hundred twenty-seven miners participated in a smoke 

training exercise in a Western underground coal mine. The average 

age of the participant was 37.3 years and average number of mining 

experience years was 12.5. Miners in groups of five, shown in 

figure 5, traversed more than 300-m of mine passageways filled with 

nontoxic smoke. Visibility ranged from 0.5 to 3-m.

Figure 5. Underground 

smoke training exercise. 

 Various devices 

were mounted on the roof in the center of the entry, placed on the floor 

or secured to the rib and worn by miners. Of all the devices (chemical 

light shapes, strobe lights, laser lights, light vests, cap lamp, reflective 

materials, thermal camera, lifeline, other) evaluated in the nontoxic 

smoke, miners felt that the two most beneficial devices for identifying 

other people in smoky passageways are light vests and lasers. These 

miners also felt that the lasers and lifelines were most beneficial in 

leading you to safety and/or out of the mine. Some of the miners were 

falls. When asked about 

felt that this technology 

ng cameras. However, 

y operations and felt that 

concerned about the durability of lifelines during fires, explosions, and roof 

their views on thermal imaging cameras or see-through-smoke devices, they 

would not apply to escape. This was mainly due to the cost of thermal imagi

they realized the importance of using this technology for rescue and recover
 

every mine rescue team or fire brigade should have access to one. Fifty-six percent of the miners that 

participated in the training reported that they have traveled through smoke at some time in their 

mining career. 

An important consideration in any fire safety program is adequate hands-on training for the entire 

workforce (first, second and sustained responders). Quality training (Conti 2001) enhances the 

awareness of mine fire hazards and promotes self-confidence. One of the strong points of the 

underground smoke training exercise was that miners felt they were better prepared for a real life 

situation. It gave them a first hand look at what they could be up against by training in nontoxic 

smoke. They also felt that it gave them a unique opportunity to evaluate devices that can help them 

navigate through smoke-filled environments. 

INFLATABLE DEVICES FOR FIRE SUPPRESSION AND PERSONNEL ESCAPE 

When mine fires can no longer be fought directly due to heat, smoke or hazardous roof conditions, 

high expansion foam (HEF) may be one way to remotely quench the fire. The firefighters and HEF 

generator can be located away from the immediate vicinity of the fire at a less hazardous underground 

location. The HEF is a convenient means of conveying water to a fire. It quenches or extinguishes a 

fire by diluting the oxygen concentration through the production of steam, blocking the air currents to 

the fire, and blocking the radiant energy from the fuel to other combustibles (Conti 1994; Havener 

1975; Nagy et al. 1960). 

To effectively use the foam method for remotely fighting fires in underground mine entries, it is 

often necessary to construct, at some distance from the fire site, a partition or stopping in fresh air to 

separate the foam generator and its operators from the smoke and toxic fire products. If this is not 

done, the HEF could flow back over the foam generator, rendering the fire attack futile. This problem 

is especially acute when the fire is found uphill in a sloping entry. Concrete block, wood, plastic 

sheeting, mine brattice cloth, or similar materials have been used for such partitions. Often, mine 

entries have irregular dimensions to which the partition must conform to avoid leakage around the 

periphery. Construction of such partitions can be a time-consuming process. After the partition is 

constructed, a hole must be cut through it to allow passage of the high expansion foam from the foam 

generator to the fire site. During a recent underground simulation for mine rescue teams and fire 

brigades in an operating coal mine, it required well over an hour to construct a partition from wood, 

metal and brattice curtain, and start the foam propagating up the mine entry. 

To address the drawbacks of constructing a partition for HEF generators, the inflatable feed-tube 

partition (IFTP) (Conti 1994; Conti and Lazzara 1995) was developed. The IFTP is a lightweight, 

inflatable rectangular bag. The device can rapidly block large openings (within 15-min), such as 

those in underground mines, and simultaneously provide a feed-tube for high expansion foam. This 

allows firefighting foam to freely flow to the fire site and control or extinguish the fire. 

The portable IFTP can be easily transported to a mine passageway leading to a fire area and then 

be inflated by a permissible fan/air blower, a compressed air line or an inert gas source (air or inert 

gas sources must be kept on to compensate for leakage). The IFTP is made from a water and heat 

resistant, lightweight fabric, such as chemically treated, rip-stop nylon. The IFTP could also be 

fabricated from a material such as Mylar or fire-resistant materials. The shape and size of the IFTP 

depend on the passageway dimensions in which it may be used. Additional information on the use of 

foam, partitions and other inerting methods can be found in the following references (Mitchell 1996; 

Conti 1995; Conti et al. 1997; Bird et al. 1999) 
 

 

Another conceptual use of an inflatable bag is a positive-pressure, inflatable walk-through escape 

device (IED). This rapidly deployed device, with its "pass-through" feature, allows extra time for 

personnel evacuation by isolating a smoke-filled entry from fresh air. The IED would be strategically 

placed in a mine entry, and then be either manually or remotely deployed during a mine fire. 

Evacuating miners would enter the IED from the smoke-filled entry and exit into the fresh airside. 

To better maintain inflation when the IED doorways are opened, a third generation positive 

pressure, inflatable escape device was fabricated and successfully evaluated in the Lake Lynn 

Experimental Mine. The unit is a rectangular bag constructed from a heat resistant lightweight fabric 

and is inflated by two fans, one of which is connected to an integral fabric tubing air distribution 

system. The IED can also be inflated by compressed air. Large C-shaped zippered doorways on both 

sides of the IED allow easy entry and exit. Because the bag is under positive pressure, it is 

impervious to outside contaminants, such as smoke, if the air intake remains in fresh air. During a 

mine fire, the IED would be rapidly deployed to temporarily isolate a smoke-filled entry from fresh 

air. If the inflating air was clean compressed air, the bag could be used as a temporary shelter (Conti 

et al 1997; Baldwin 1996). The use of a fan for inflation, however, would require that the fan remain 

in fresh air or that filters be installed on the fan to cleanse the mine air of any contaminants. Mine 

rescue teams could also use the IED as an airlock system during rescue and recovery operations and it 

could be rapidly advanced as mine recovery progressed. For this application, an inert gas source could 

be used to inflate the IED if necessary. The performance of the third generation IED was assessed 

during mine rescue team training simulations conducted in the Lake Lynn Experimental Mine. The 

IED was deployed in 5 to 10 minutes and isolated a smoke-filled passageway from the fresh air base. 

Fully equipped five to seven member mine rescue teams can enter or exit the IED without deflating 

the unit. The IED has been successfully demonstrated at numerous Open Industry Briefings on Mine 

Fire Preparedness held at Lake Lynn Laboratory and operating coalmines. Briefing participants and 

miners walked down a non-toxic smoke-filled entry and passed through the IED to reach fresh air. 

This device successfully isolated smoke-filled entries from fresh air, and mine personnel effectively 

passed through the device to the fresh air base or back into the smoke-filled entries. 

SUMMARY 

This cooperative research effort between NIOSH, state agencies, and mining companies offered 

an excellent opportunity to provide realistic training to mine rescue teams, fire brigades, first 

responders, and miners in general, and to evaluate new and existing technology that may be used for 

underground mine emergencies. For example, rescue teams have identified green as the most visible 

colored lightshape in both white and black smoke. Some teams have now added chemical lightshapes 

to their cache of rescue team supplies. 

Strobe lights were useful for mapping out an escape route for evacuating miners. Activation of 

the strobe lights by the wireless, through the earth signaling system was successful. Additional 

research would be required to evaluate the feasibility of using these devices in larger mines and to 

incorporate audio output with each strobe light unit. 

During smoke training exercises, red and green laser pointers were effectively used to negotiate 

travel through smoke-filled passageways. The green laser pointer was the most visible color seen in 

white smoke. These realistic training exercises offered the workforce an excellent opportunity to 

evaluate devices that can help them navigate through smoke-filled environments and better prepare 

them for real emergencies. 
 

By using the new-lighted team lifeline, team members have freedom of movement between the 

captain and tail-person. They can visually see the rope, their own position and are more flexible to do 

activities such as carrying supplies, erecting stoppings and constructing roof supports. The team 

lifeline also alleviates tripping and falling problems. The electroluminescent fiber of the light vest 

allows team members and personnel working in darkness, smoky conditions or around moving 

machinery in low light areas to be seen more easily. 

Escape from complex underground passageways could be improved by using a continuous 

lifeline. Utilizing directional cones and double cones on the lifeline would not only lead personnel 

escaping in smoke-filled entries in the right direction, but also alert them that an obstacle of some sort 

is nearby. 

The m-Comm communications system shows merit for improved communications for emergency 

responders. Utilizing the voiceducer, with the present radiating transmission line at Lake Lynn 

Laboratory, has shown potential for improved wireless communications for mine rescue teams. 

Additional research is required to incorporate the antenna into the main lifeline. 

The thermal imaging cameras have proven useful for mine rescue exploration and recovery in the 

smoke-filled mine passageways. However, the simulations suggested that new protocols need to be 

developed when mine rescue teams explore with these IR devices, because the team member with the 

thermal imaging camera can travel smoke-filled entries much more rapidly than other team members. 

Both inflatable devices have shown merit in providing a relatively rapid method for isolation of a 

mine fire and use with a foam generator for fire suppression, or for personnel escape and rescue. The 

inflatable partition can rapidly block large openings, such as those in underground mines, and 

simultaneously provide a feed-tube for high expansion foam. The inflatable escape device could be 

used as an airlock system during exploration by mine rescue teams and could be rapidly advanced as 

mine recovery operations progressed. 

These technological advancements can improve the state of readiness for rescue personnel and 

increase the chances of survival for personnel escaping from underground emergencies. 

ACKNOWLEDGMENTS 

The author wishes to thank C. P. Lazzara, L. Chasko, F. A. Karnack, W. Slivensky, D. D. Sellers, 

and J. H. Jansky, Pittsburgh Research Laboratory, J. Cool, D. Eppley, J. Stanchek, and L. Stowinsky, 

Pennsylvania Bureau of Deep Mine Safety, J. Holt, Consol Energy Inc., and L. Derick and B. Krump, 

Twentymile Coal Company for their contributions to this effort. 

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