From The 9/11 Commission Report

One clear lesson of September 11 is that individual civilians need to take responsibility for maximizing the probability that they will survive should disaster strike. Clearly, many building occupants in the World Trade Center did not take preparedness seriously. Individuals should know the exact location of every stairwell in their workplace. In addition, they should have access at all times to flashlights, which were deemed invaluable by some civilians who managed to evacuate the WTC on September 11th.