AMC 25.831(a)
Ventilation
The supply of fresh air in the event of the loss of one source, should not be less than 0.18 kg/min (0·4 lb/min) per person for any period exceeding five minutes. However, reductions below this flow rate may be accepted provided that the compartment environment can be maintained at a level which is not
hazardous to the occupant.
from CS 25