"... but for those facing a terrorist bomb such protection is likely to be adequate, and much safer than, say, being stuck in traffic on the Beltway when the fallout begins to settle. Also, people sheltering in place won't tie up roads, making it easier for emergency services to get where they're needed. So the Obama Administration wants to encourage people to shelter in place rather than head for the hills in the event of a nuclear attack. Even sheltering for a few hours, or a couple of days, lets radiation levels fall dramatically and avoids road tie-ups for later evacuation."
Think about it.