Sheltering in Place, how to handle radiation exposure.
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... your real problem is the radioactive dust that the blast threw into the air. ... eventually expose 200,000 people to lethal doses of radiation if they stay exposed and unprotected in the fallout path for 24 hours. Sitting downwind in gridlock, with your vehicles windshield shattered, goes a long way toward giving you a lethal dose. All sorts of simple alternatives moving away from downwind, seeking proper shelter, even taking a shower go a long way toward saving you.
Fallout is simply radioactive dust, launched miles into the air in a mushroom cloud and then carried on the wind. Much of it is alpha particles, whose radiation cannot penetrate bare skin, or beta particles, which cannot penetrate layers of clothing. Both are most dangerous if inhaled or if they settle on food that is eaten unwashed. More deadly are the gamma rays, whose radiation can go through walls. But even gammas cannot hurt you from cloud height. The danger starts when the dust settles to earth.
The ideal is to avoid the fallout in the first place. In apocalyptic gridlock, you cannot drive very far. But you may not have to. Normal winds blow the cloud into a long but narrow plume, just a few miles across. In typical Washington-area weather, Virginia, Montgomery County in Maryland, and most of the District itself are not in the fallout path at all. People in the path could conceivably walk out of the fallout zone in the 10 or 15 minutes before the dust begins to fall if they know which way to go.
But, of course, you cannot count on perfectly typical weather. The wind might shift; the breeze you feel at ground level may be blowing crosswise to the radioactive clouds five miles up; a still day might cause the fallout to seep outward slowly in all directions; sudden rain or snow could wash the dust out of the sky, heavily dousing everything beneath the storm but sparing areas farther out.
If you do not want to trust in weather and traffic, the alternative is what the experts call sheltering in place. You want to be in a building, as solid as possible to block the gamma rays, as airtight as possible to keep out radioactive dust. You need to turn off air conditioning, close vents, seal the seams around windows and doorways. If you wondered what former Homeland Security Secretary Tom Ridge was talking about, this is what you need the duct tape for. Abandon rooms with windows broken by the blast.
The dust that does not seep into the building will settle outside, on the roof and on the ground, emitting gamma rays. A car with an intact windshield stops 30 to 50 percent of the radiation probably not enough, however, to save someone whos inside the car and stuck in traffic a few miles downwind of ground zero. A wood-frame house, similarly, stops just 30 to 60 percent of gamma rays. A windowless basement stops 90 percent. The middle floors of a concrete apartment building, safely away from both roof and ground, stop 99 percent or more. But there is no 100 percent protection.
For those whom evacuation and shelter fail or for those, like the thousands fleeing in blind panic, who never try either there is still decontamination. A lethal dose of radiation takes time to build. The sooner the radioactive dust is off the skin, the better. And it is not that hard to remove. Radiation contamination is easier than chemical, said Col. David Jarrett, a medical doctor and the director of the Armed Forces Radiobiology Research Institute in Bethesda. Simply removing the clothes and washing takes off up to 90 percent.
Every major Washington-area hospital has some decontamination facilities, but 10,000 radiation patients in one day would swamp them. So mass decontamination falls to fire departments, with their mobile pumps and generators; their protective gear; their hazardous-materials experience; and, because both Maryland and Virginia have nuclear power reactors, their years of radiation training. Area firefighters can quickly set up special decontamination tents, and they have plans to take over buildings that have lots of showers so high school gyms, for example, are a good place to head for. In the chaos of those first hours, said Michael Cline, state coordinator at the Virginia Department of Emergency Management, the real key is to make sure people go to those facilities. It will take every firefighter available to man the decontamination sites, and every cop to control the crowds pouring in panic out of the city.
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NUCLEAR THREAT INITIATIVE [NTI]
Sheltering in Place excerpt, during fallout.