My wife was plagued by one of her coworkers that was preaching the government recommendations: flashlights, batteries, food for three days, double checking the seals on your windows and doors. She, herself was going after work to buy duct tape to seal her windows.
I was like, how farking stupid would you have to be? 3 Days worth of food? Have you seen the US government clean up *anything* in three days? As for power outages we have freak, terroristic thunderstorms and rogue, falling trees that force us to the sad extreme of keeping an DC light source already.
Middle of Winter, all of your house's orifices sealed tight for 'safety', and a three+ ton air pump shoving all the great, chemically and bacterially UNfiltered air into it. Unless you still heat your house with some sort of wood-burning/water-boiling system, fresh air is being pumped in from somewhere, and I dunno of any system guaranteed to filter Anthrax or Ricin. Fact is, (and Jafo can back me up, i think) building codes *require* venting of some sort, pretty much ruling out the hope of hermetically sealing your house.
I want so much to go from house to house, laughing at all the paranoid people sealing their windows with duct tape. You might as well wear a aluminum (spelling Amer-i-KAN) foil hat to protect against mind control. On the other hand it would have been even funnier to see the reactions of Americans if the government had asked us to turn off our heating/air conditioning in the event of an attack. What? How dare you mandate discomfort!