To limit the probability of persons contacting or colliding with items at the ceiling level, which could lead to harm to persons.
To limit the probability that exits will have insufficient headroom clearance to permit efficient egress in an emergency situation, which could lead to delays in the evacuation or movement of persons to a safe place, which could lead to harm to persons.
To supersede the requirements of Sentence 22.214.171.124.(1), which would otherwise require a greater headroom clearance in exits, and of Sentence 126.96.36.199.(1), which would otherwise require a greater height in doorways, and permit a reduction, on the basis that the reduction is limited and should not negatively affect exit usage.