Occupational safety and health regulations state that the safety curtain must be able to resist fire and thereby prevent (or at least hinder) fires starting on stage from spreading to the auditorium and the rest of the theatre, reducing injuries to audience members and members of staff.
The curtain is extremely heavy and therefore requires its own dedicated operating mechanisms. In an emergency, the stage manager can usually pull a lever backstage which will cause the curtain to fall rapidly into position. Alternatively, heat-sensitive components can be built into the rigging to automatically close this curtain in case of fire and finally it may be released electronically by a building's fire control system if any alarm box is operated. It can also be flown in and out, as regulations in some jurisdictions state that it must be shown to the audience, to prove its effective operation, for a certain amount of time during every performance. This usually occurs during the intermission.

In the event of a fire, the use of smoke doors and fire curtains means that the stage area effectively functions as a chimney. The heated air rises and leaves through the smoke doors, and this puts the building into negative pressure, which in turn draws fresh air in through any open exit doors. Patrons waiting to exit will have fresh breathing air until the exit doors close. The exit doors which open out will be drawn closed tightly by this draft once they are no longer held open by evacuees. Once the doors are closed, the fire loses its oxygen source. If the doors are then opened again, a backdraft can occur.