"There has been some confusion over that," he said, placing some of the blame on the media, which seemed to focus on duct tape and plastic to the exclusion of other more mundane tips. "The most important message is to listen to what your local authorities are saying at the time."
Steve Fetter, a physicist and professor in the School of Public Affairs at the University of Maryland, agreed that - while the government's other home precautions make sense - sheets of plastic held in place by duct tape are far from foolproof.
"You can reduce infiltration of outside air by about 50 percent, and there might be some lives saved by that, but in a very severe attack, it wouldn't matter if you had plastic up or not. There's a pretty narrow range of conditions under which this would be useful."
And staying in a well-sealed safe room too long, he added, could, depending on the room's size, lead to death by carbon dioxide poisoning in a matter of hours.
More likely, he said, a homeowner's attempt to seal off a room with plastic would probably allow enough air to leak in. "But, of course, that's the problem - anything else could leak in as well."
With the bomb shelters of the 1960s now mostly shut down, and so many new weapons, gases and chemicals to worry about, the options are few, Fetter said.
"The effectiveness of civil defense is just so limited that we need to put almost all our effort into preventing the bad thing from happening in the first place."