chlorine gas detection requirement?

[bevfs]

hi all
is there a requirement to install chlorine gas detection in swimming pool plant room. The water processing/filter machine is sited here with chlorine25kg x15,shulphuric acid 25kg x 20,also stored.Its a new system 2/3 years old &bunded.In the event of chlorine gas being emitted through systems failure /human error etc ,and I know not fire ,is it a requirement to have a warning system either independent or linked to the fire alarm system to necessitate an evacuation?