Calculating Casualties

​WHEN AN AREA is hit by a major disaster, an early challenge for responders is estimating how many fatalities and casualties are likely to have occurred. Fortunately, a software program called Electronic Mass Casualty Assessment and Planning Scenarios (EMCAPS) helps them do that.

Developed by the Johns Hopkins University Office of Critical Event Preparedness and Response (CEPAR) and the Johns Hopkins University Applied Physics Laboratory, EMCAPS is used by fire departments, hospitals, and emergency planners around the country. Now, taking advantage of new technology and lessons learned from five years of field use, researchers are working on an updated version, expected to be available in 2012.

Jim Scheulen, CEPAR’s executive director, has worked on the tool since its inception, and he said the idea was borne from disaster preparedness planning for the hospital at Johns Hopkins. Researchers were assessing a hypothetical situation in which a bomb exploded at Camden Yards, home of the Baltimore Orioles baseball team, and some were guessing that about 45,000 people would likely be injured. “That’s when I just sort of lost all interest because I thought, you know what? First of all, there’s no way that 45,000 people are going to get hurt. Second of all, quite frankly, if 45,000 people are all hurt at the same time, no amount of planning’s going to help us. We’re just going to have to deal with it. And so, I thought, gosh, what we need is some way to get some sense of what an event like that really would mean,” says Scheulen.

With the help of the Applied Physics Laboratory and various experts in fields such as explosives, the CEPAR scientists identified parameters that would affect the extent of devastation in a disaster. Factors include the type of explosive, the weight of a bomb, the population density of the area, and the wind speed that might affect toxins in the air. Scheulen and the other researchers formulated different scenarios for the EMCAPS tool that allow users to input the various parameters and come out with a projected casualty number for the given scene.

“EMCAPS is what we used to call in the software business sort of an expert system,” for situations when you may not have, say, a biohazard or explosives expert on hand, says Karl Rehn, training manager with the Texas Engineering Extension Service, part of the Texas A&M University System. “It sort of condenses the knowledge of those experts so that you can tap it very quickly in an assessment situation when you may not have everybody that you need.”

Casualty estimates help the responsible parties better determine how many hospital beds, first responders, and ambulances may be needed. The estimates also give emergency personnel some indication of what they may be in for. EMCAPS is used by fire departments, hospitals, and emergency planners around the country.

The new version makes numerous updates, including the ability to lay the disaster on a map and pinpoint where the deaths and injuries are likely to occur. The scenarios have also branched out and become more specific. For example, the bomb scenarios have expanded to include a truck bomb, a car bomb, an open-air bomb, and other such scenes.

“What we’re trying to do is not just necessarily build EMCAPS 2 so that it’s all absolute, horrible, catastrophic stuff, but we’re trying to build it so that, ‘gee, this stuff may really happen,’” says Scheulen, who notes that the researchers have added scenarios like salmonella outbreaks to the mix.

EMCAPS does not guarantee getting the casualty estimate down to the number. That would never be possible and is not really necessary. “I’m really trying to get a sense of, is it a hundred or is it a thousand. I don’t need to know if it’s 101 versus 98,” says Scheulen.

As useful as EMCAPS is, just one tool is not enough for risk assessment and disaster planning. Rehn says he teaches his students to use various software tools together. He says the different tools are “like a hammer versus a wrench versus a screwdriver.” One option he’d like from EMCAPS in the future is for it to be a mobile application like a smart phone or a tablet, “where someone could have it in the field with them a little more easily,” he says.

There are some scenarios EMCAPS researchers still have trouble with. For example, EMCAPS would not have been able to help in a situation like the recent massive earthquake in Japan. Although researchers are hoping to add earthquake scenarios to future versions of EMCAPS, earthquake casualties can be extremely difficult to calculate, says Scheulen, because it’s hard to model all of the variables for factors such as how far from a densely populated area the earthquake’s epicenter is and the kind of buildings that are in the affected area.

Other scenarios that are difficult to model are ones that have never actually happened, such as anthrax getting into the U.S. food supply.