Panic bars and exit devices
A push bar lets anyone leave with one motion, even in a crowd or in the dark.
Where they're required
Building and fire codes generally require them on exit doors in assembly spaces and larger occupancies. Check with the local fire marshal for your building.
Signs of trouble
The door doesn't latch, the bar sticks, or it needs a shove to release. Any of these is a safety problem.
Getting one fitted
Panic bar installation includes aligning the latch and strike so the door closes and locks every time.