A growing number of states say the answer is the same: Head for the medicine cabinet.
From California to Connecticut, state legislatures are asking the federal government for supplies of potassium iodide pills to treat some of the most devastating aftereffects of radiation. So, public health officials are getting ready for a barrage of questions from citizens.
"Education is going to have to be an important part of the process," says Dr. Mark Horton, the health officer for Orange County in southern California, where hundreds of thousands of pills will be distributed.
Federal officials first considered the idea of potassium iodide pill distribution in 1995, but a plan was not put into place until April 2001. The World Trade Center attacks accelerated interest in the pills, says Rosetta Virgilio, a spokeswoman for the Nuclear Regulatory Commission.
Fourteen states have asked for supplies of pills, and most of the shipments have already been sent, Virgilio says. The states are: Alabama, Arizona, California, Connecticut, Delaware, Florida, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Ohio, Pennsylvania and Vermont.
The NRC will provide two potassium iodide pills each for residents who live within 10 miles of a nuclear plant, Virgilio says.
The radioactive chemical iodine is released when a nuclear plant has a radiation leak. Iodine enters the body and builds up in the thyroid, where it can cause cancer years later.
The potassium iodide pills fill the thyroid with non-radioactive iodide, explains William Miller, a professor of nuclear engineering at the University of Missouri at Columbia. "There's no room in the thyroid for (more) iodine, so the radioactive stuff gets eliminated from the body without getting concentrated."
Local residents should have a few hours after a nuclear plant accident to take the pills, Miller says. The pills last for 24 hours; according to a U.S. Food & Drug Administration report, they can provide protection if taken before a radioactive cloud approaches or as long as three or four hours afterwards.
Side effects of the drug are rare if it's taken for short periods.
However, radiation causes a variety of other medical problems, which typically appear years later in higher rates of cancer for those who are exposed. "This is not a universal anti-radiation pill," Horton says.
In California's Orange County, health officials will have to discuss exactly how to get the pills to residents, he says. They could be mailed or distributed through convenient locations near the San Onofre Nuclear Power Plant, he says: "The devil is in the details."
However, Miller suggests the devil may actually be in the very idea of distributing the pills in the first place.
"Our society tends to continue to overact when it comes to how harmful radiation is to people," he says. "It's hard for me to perceive any kind of accident in the Western world that would give anyone close to a lethal dose of radiation."
What To Do
Learn more about the use of potassium iodide as a protective agent in this report from the U.S. Food & Drug Administration.
The National Institutes of Health offers this report about potassium iodide.