Imagine sitting in a subway car on the way to the office for another day of work, when suddenly you can not breath. You look around and notice that other people around you are having the same problem. You push and shove other people aside to try and get to the door, but the doors are sealed shut. People are yelling, screaming and pounding on the doors tyring to get out. But no one is coming to help. People are starting to loose consciousness. In this incident there were no technical errors or problem with the circulation of air. It was ....