Thermal imaging a tool in Oklahoma tornado search efforts

A US flag is seen amongst the debris of a torando devastated house on May 21, 2013 in Moore, Oklahoma. Families returned to a blasted moonscape that had been an American suburb Tuesday after a monstrous tornado tore through the outskirts of Oklahoma City, killing at least 24 people. Nine children were among the dead and entire neighborhoods vanished, with often the foundations being the only thing left of what used to be houses and cars tossed like toys and heaped in big piles. AFP PHOTO/Jewel Samad (Photo credit should read JEWEL SAMAD/AFP/Getty Images)

Rescue workers are bringing to an end the search for survivors in rubble of the tornado-ravaged city of Moore, Okla. At least 24 people have been killed by the massive twister that ripped through the Oklahoma City suburb on Monday.

Among the tools rescuers used in looking for people in the rubble were thermal imaging cameras (TIC), devices that use infrared radiation to detect a person or object based on the electromagnetic spectrum, where colors correspond with wavelengths. They essentially look for heat signatures given off by warm-bodied humans or animals.

Thermal imaging tools may have been used by the military as early as the 1940s, but it wasn't until the 1990s that fire stations across the country began to purchase thermal imaging cameras, which at the time were wildly expensive.

In 2000, the Los Angeles Times reported that a thermal imaging camera could cost between $18,000 and $25,000. Today, smaller versions of the devices can be bought online for about $1,000.

In a 2005 report by the National Institute of Standards and Technology (NIST), a camera was reported as costing about $10,000. But the investment gives emergency responders access to areas that are dangerous or inaccessible without these tools.

According to a report by the U.S. Fire Administration, "First responders may use thermal imagers for search, rescue, target identification, helicopter pilot or vehicle driver vision enhancement, as a tactical decision aid, wildland size up, hot ballast and hidden fire identification, code compliance, as a diagnostic tool for emergency medical personnel or as a command and control tool for incident commanders."

Bob Athanas serves on the New York City Fire Department (FDNY) and is the chairman of National Fire Protection Association's (NFPA) Electronic Safety Equipment committee, which is in charge of creating a standard for the Fire Services Thermal Imagers. In speaking with, Athanas says that the thermal imaging tools are not the answer to everything.

"It has limited applications," Athanas told "It's a tool in a cadre of tools. For emergency responders on whole, the applications are far greater."

One of the limits of thermal imaging is that the technology can't penetrate walls. And there are two variations to consider when talking about TICs: long-wave length, which is true infrared and mid-wave lengths, which is night vision.

"The applications for urban search and rescue are limited. The technology does not allow you to see through walls," said Athanas, adding that people could theoretically be trapped in void spaces -- pockets inside the debris that allow people to survive.

"But if there's a representation of a body part the potential exists that the person can be seen from a quick scan," Athanas said.

The search for survivors concluded on Tuesday, with emergency crews using everything from cadaver dogs to high-tech devices. CBS Oklahoma City affiliate KWTV reports some members of the National Guard used thermal imaging in the search.

Moore Fire Chief Gary Bird said that three searches of each building were conducted to be sure there were no more bodies or survivors.

"I'm 98 percent sure we're good," Bird said.