See the NFPA 101, 2000 Life Safety Code
Examples of devices that might be arranged to release latches include knobs, levers, and panic bars.
This requirement is permitted to be satisfied by the use of conventional types of hardware, whereby the door is released by turning a lever, knob, or handle or by pushing against a panic bar, but not by unfamiliar methods of operation such as a blow to break glass.
The operating devices should be capable of being operated with one hand and should not require tight grasping, tight pinching, or twisting of the wrist to operate.
Joe Tedesco, NEC Consultant