This part of BS 4N 100 provides guidance on the physiological factors which should be considered when designing oxygen systems for use within aircraft.
BS 4N 100-4:1999 history
2018BS 4N 100-4:1999+A2:2018 Aircraft oxygen systems and equipment - Guide to the physiological factors
1999BS 4N 100-1:1999 Aircraft oxygen systems and equipment — Part 1: Design and installation