Super blow.

Take the concept of the airport screening device that blows air at you and then collects that air to see if your carrying drugs or explosives. Expand the sniffing technology to a 100 foot long corridor. People would pass through this corridor where they would be subjected to a continous blast of air. The air would then be gathered for examination. If an explosive was detected the whole corridor would go into lock down. The corridor would have several blast doors so as to contain the bomber with the least amount of victems. Sort of like the game jezzball. The super blow system would act as the entry ways to subway systems, entries to sporting events and perhaps even shopping malls.