The egress path has to be lit so people can see to get out. IBC 1008 requires the means of egress to be illuminated whenever the space is occupied, providing at least 1 foot-candle at the walking surface. Critically, the illumination must be backed by emergency power: on loss of normal power, egress lighting must maintain at least an average of 1 foot-candle (0.1 minimum) for a duration of 90 minutes.
This applies along corridors, at stairs, and at exit discharge — the whole path, not just the exits.
The common mistake is designing egress lighting on normal circuits without the required emergency backup, or a layout that leaves dark spots below the minimum at stair landings or turns. Reviewers check that egress-path fixtures are on emergency power with the 90-minute duration and that the photometric layout meets the foot-candle minimum along the entire route — this ties directly to the emergency-power guide, since the two requirements are enforced together.
This guide describes the model code for general understanding and is not a substitute for the adopted code and amendments enforced by your local authority having jurisdiction. Verify all figures against your jurisdiction's codes of record.