"The 'exit access' is that portion of the means of egress that leads to an exit, and includes halls, corridors, aisles and other walking or escape paths. The purpose of maintaining minimum egress widths is to assure that occupants have a clear and unobstructed path to an exit where they can escape dangerous conditions."
Coffee Break Training - Fire Protection Series No. 2005-2
United States Fire Administration: http://www.usfa.fema.gov/