May 21, 2013 at 5:20 PM ET
Search teams, including some with trained dogs, are scouring the rubble left behind by the monster tornado that flattened miles of homes, schools and businesses in Oklahoma City and its suburbs Monday. More than 100 people had been found alive by rescuers as of Tuesday afternoon.
While it's uncertain exactly how many people are still missing, rescuers are up against the clock to find survivors, experts say.
The window of opportunity for someone to still be alive but out of sight under the wreckage is usually about 48 hours, says Bill Dotson, president of the Search Dog Organization of North America.
“We have got probably until tomorrow night to be optimistic,” Dotson, who has been training search dogs since 1977, said in a telephone interview.“There is an urgency to this. There is a time factor, but it is always possible that we are going to find somebody," added Dotson, who is not involved in the Oklahoma search and rescue effort.
Authorities said they were still searching Plaza Towers Elementary School in Moore, Oklahoma, where seven children died, but said search dogs had not found anyone else amid the shattered pieces of wood, metal and concrete. Among the searchers are dog units from Texas, Missouri and Nebraska.
Search and recovery experts know it’s possible to survive a building collapse. People have been pulled alive from impossibly small spaces after quakes, explosions and accidents. Most recently, a young mother was pulled alive from the pancaked remains of a Bangladesh clothing factory, 16 days after the disaster.
The keys to survival are that something must have protected the person from being crushed, they’ll need to be somewhat mobile, they’ll need air and, after a few days, water.
“Voids – we look for voids,”“We look at the wreckage to determine survivability,“ said Dotson, who's helped train dogs for mine rescue, rescues after disaster and to help look for people who are lost or missing.
Survivors will have to have escaped the worst of the flying debris and gotten stuck under a piece of the building’s frame, or something similarly strong and stable.
“Maybe they are buried pretty deep in a basement, a house collapsed on top of it, and nobody could get to them,” Dotson says. “We know from earthquakes that 48 hours is the optimal time to locate living persons and find them alive and get them to hospital.”
Even a minor injury can kill someone after a few days, Dotson notes. “Imagine someone has a cut to the leg. They’re fine, and it stops bleeding on their own,” he says. “Then a day goes by and they start having an infection. Then a second day goes by and the infection’s worse. The mere infection can kill a person who was alive when the tornado left.”
Being completely pinned can also cause what's known as crush syndrome, which severely damages the nerves and muscles. Releasing the victim can even precipitate a heart attack or a stroke, so rescuers must take care.
Specialized equipment can check for the carbon dioxide exhaled by survivors, but it’s usually quicker to use a trained dog.
“They are very successful and very efficient at locating people that you can’t see or hear,” Dotson says. “If someone’s five or six feet down in the rubble, it can be pretty hard to hear them.”
Rescue dogs are specially trained to detect people who are still alive. They can smell exhaled breath, for a start, says Dotson. “Imagine a picture of Pigpen from the Charlie Brown cartoons,” he said. “We all put off molecules that a dog can pick up. Their sense of smell is extremely acute.”
It takes years of training, however – people’s pets are very unlikely to help rescue anyone, even their own families. “They are absolutely, positively of no help whatsoever,” Dotson says.
If someone was trapped for longer than a few days, water would be the next immediate need, experts say. “People can last without water intake, if conditions are pretty good, for around five days or a week,” says Randall Packer, a professor of biology at George Washington University.
Some survivors have said hearing the sounds of the search have given them hope, and the will to hang on.
People can last for weeks without food, but looking at images of the devastation in Oklahoma, Dotson says he doubts any buildings have intact enough spaces for anyone to survive that long.
Fire and rescue officials said they would check every structure in Oklahoma from top to bottom.
“We are always optimistic that the next foot the dog puts down, he is going to say yes, we have got somebody here alive,” Dotson said.