Sunday, March 20, 2011

Wash It Off: Avoiding Radioactive Materials by Cleaning

I am old enough to vaguely remember what a fallout shelter sign looked like. The techniques the United States government suggested for avoiding the dangers of radiation half a century ago were obviously misplaced. It is easy to laugh at the “duck and cover” jingle, but that technique — stay low and protect your face from radiation — is no more erroneous today than the idea of a fallout shelter. Both techniques are intended to help avoid radiation burns, but they may not be of any help in avoiding the kinds of radiation that most of us have a chance of encountering, and surviving, in the event of a disaster.

The most immediate techniques are the most familiar and obvious. The surest protection from any localized release of radiation is distance. If you are one kilometer away from a radiation source, the intensity of radiation is one millionth of the intensity you would find if the radiation source were an arm’s length away. You reduce the radiation exposure by 99 percent just by taking the first few steps away.

A radiation leak can send heavy particles long distances on the air, and the best techniques for protecting yourself from radioactive particles are the same techniques you might use with dust and dirt. Recent radiation stories from Japan tell of people washing the bottoms of their shoes; washing their clothes; taking showers; keeping building and car windows closed; wearing dust masks. People are staying indoors when they can, but indoors does not mean underground. Radiation resulting from from the uranium naturally present in soil and rocks in much of the world may make ambient radiation levels in the basement of a building higher than the radiation levels above ground or even outdoors.

The “wash it off” approach to radioactive contamination probably strikes some people as a joke. To people conditioned to fear radioactive particles in even the smallest amounts, it’s hard to change the “you might die” reaction to “wash it off.” But the “wash it off” response is more constructive for the amounts of radioactive materials that the largest numbers of people are likely to come in contact with in a disaster.