The Five Don'ts Of Thermal Imaging

Thousands of fire departments across North America have placed thermal imagers (Tis) into service. While some departments have only one or two cameras, others have a TI on every fire company. Tis are clearly making the transition from "cool toy" to "critical tool"; however, a thermal imager is like any other tool on the fireground: properly used, it saves lives and property; improperly used, it can injure firefighters. Firefighters should regularly train with this new tool, carefully avoiding the "Five Don'ts of Thermal Imaging."

  1. Don't "tunnel vision" onto the image. Structural firefighting is one of the primary uses of thermal imaging. A thermal imager allows the firefighter to regain eyesight in a structure fire. As a result, search times are dramatically reduced, while search accuracy and firefighter safety are greatly improved. However, with regained visibility the firefighter is often tempted to "tunnel vision" onto the display, encouraging him to navigate only with his eyes.

    Thick smoke can encourage this behavior. In thick smoke, the only thing a firefighter can see is the screen of the TI. This almost forces the firefighter to look at the screen, and it takes an extra measure of control to not fall into this trap. Often times, if a firefighter relies only on eyesight to enter a structure, he will most likely need to rely on his eyesight to exit a structure. Therefore, if the firefighter loses the use of the TI for any reason, he risks becoming immediately disoriented.

    A firefighter should use the TI to scan a room slowly and completely, searching for victims, identifying safety issues, and building a "mental map" of the room prior to entering. This not only allows for faster team movement, but it also reinforces the need for "mental mapping" and enables the firefighter to maintain reference points in darkness.

  2. Don't mistake sight for safety. Thermal imagers remove the sense of darkness often found in the blinding effect of smoke, giving firefighters the ability to see furniture and doors. As a result, they can be tempted to assume it is safe to walk.

    When using a TI, firefighters should not confuse the ability to "see" with the presence of a safe environment. Firefighters should remember that when they "see" with the TI, they are not getting the same perspective as they would get with their eyes. Depth perception and peripheral vision are reduced with a TI. Many objects appear different when viewed with a thermal imager. A puddle of water can look indistinguishable from a hole in the floor. Of course, to walk with a TI, the firefighter would have to use it constantly, requiring "locking on" to the imager. This violates Don't number 1. Essentially, if a firefighter would crawl without the TI, he should crawl with the TI as well.

  3. Don't think all victims are "white" on the screen. It is an unfortunate truth that few fire departments have regular access to structures in which they can light training fires. Without access to live-fire training, firefighters must resort to conducting drills in ambient environments. This strategy can be problematic for realistic TI training.

    A thermal imager simply displays temperatures differences. The warmest thing in any field of view is generally white, while the coolest object in any field of view is generally black. The temperature of a human does not vary much -- it remains fairly constant. In an ambient environment, a human is generally warmer, thus appearing white; however, in the midst of a structure fire, a human victim may be cooler than the ambient temperature, thereby appearing dark gray or even black.

    During TI training, firefighters should be constantly reminded that temperature is relative on a TI. A human may show as white in a cool environment, gray in a warm environment or black in a heated environment. Therefore, firefighters should be training on shape, not on color, when practicing search techniques.

  4. Don't expect a thermal imager to do everything. First and foremost, firefighters should remember that Tis do not "see through" buildings or people. One cannot "look" through walls, floors or obstructions to find victims.

    Second, infrared energy does not travel well through glass or water. While glass is transparent to visible light, it is nearly opaque to infrared. The same is true with water. During exterior size-up efforts, Tis cannot be used to see through closed windows. Tis assist water rescues only if the victim maintains a heat signature above the water. Inside a structure, an activated sprinkler head may appear as a black cone showering down, masking nearby victims or fire from the TI. Firefighters should use their Tis as frequently as possible to familiarize themselves with the limitations, as well as explore additional, creative uses.

  5. Don't forget the basics of firefighting. If there were only one "Don't," this would be it. Firefighters absolutely, positively must remain proficient at basic firefighting skills. Thermal imaging is a valuable technological tool; however, Tis will not put out the fire. Firefighters need to engage in solid, fundamental firefighting to ensure their own safety and the proper completion of their goals.

    While the TI will make search efforts easier and faster, the imager should not supplant the standard practice of right- or left-hand search patterns to maintain orientation. Firefighting companies should still ventilate structures in a timely and effective manner to remove the heated gases and smoke. While the TI helps to monitor structural integrity, it cannot see hidden trusses, nor can it make compromised trusses carry their loads longer. Firefighters still need to be aware of the structural limitations of a building and the dangers therein. Just as a helmet and turnout gear do not make a person invulnerable, neither does a TI.

    Fortunately, every day, more fire departments understand the benefits of thermal imaging and add this powerful tool to their departmental resources. TI manufacturers have responded to fire service demands for easily operated cameras, but there are still educational hurdles that fire-training personnel must address. Rely on basic skills, enhance those skills with thermal imaging and train consistently with your thermal imager. Avoiding the "Five Don'ts" will greatly enhance your success and improve firefighter safety.

BRAD HARVEY is the Thermal Imaging Product Manager at Bullard. He is a veteran of public safety as a firefighter, police officer and paramedic and is certified through the Law Enforcement Thermographers' Association (LETA) as a thermal imaging instructor. Harvey has worked as a high-angle rescue instructor and is a certified rescue technician and fire instructor. If you have questions about thermal imaging, you may e-mail him at