Many Americans have spent the past few days preparing to combat terrorism with duct tape and plastic sheeting. On Monday, the White House suggested people purchase such supplies to seal up doors and windows in the event of an attack using a chemical or biological weapon. That government warning set off a race to hardware stores and home improvement centers but left bio-terrorism experts puzzled. As NPR's Jon Hamilton reports, many experts say most people don't need an airtight room, and those who do will probably want something safer than duct tape and plastic.

According to Randy Larsen, director of the Anser Institute for Homeland Security, duct tape, plastic sheeting and other "safe room" supplies are largely ineffectual. He says the public should focus on more important preparations, such as having a plan to reach every family member at any hour in case of emergency. Families, he adds, also need to ask questions about transportation and logistics.

"Who is going to pick up the kids from nursery school if you can't get there?" Larsen said. "Who is going to take care of your pets if you can't get home for three days? You better be coordinating that with your neighbors and relatives."

Once those issues are taken care of, Larsen says, people should put together a disaster-supply kit like the one suggested by the American Red Cross, which includes items such as sleeping bags, extra clothing, a battery-powered radio and any necessary prescription drugs.

Larsen says these issues need to be handled before consumers start thinking about creating an airtight space to seal out chemical or biological agents. But according to Cliff Enz of the Regional Environmental Hazard Containment Corporation (REHCC) in Landover, Md., creating that airtight space poses another problem.

"Duct-taping your windows and putting plastic sheeting over everything is only secure as long as your air supply lasts," Enz notes. "When your air supply goes, so do you."

REHCC sells a suitcase-sized system that turns into an airtight tent equipped with a special air pump that filters out particulate matter. Enz says it's the same one owned by more than a million families in Israel, where consumers have spent years preparing for biological and chemical attacks.

However, such safe-room systems cost upwards of $3,000 each, and Enz says their usefulness is questionable even in high-risk areas such as New York or Washington, D.C.

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