I wasn't suggesting the public, staff can do it. It discharges into the engine room and not the PC van compartment. The engine room door should be gas tight as if it's not the next door aft has to be...which it's not. The only consideration should be leaking bottles in which case a gas detector should be fitted. Its was discussed here https://www.railforums.co.uk/threads/light-engine-hst.194456/ 43096 will be along at some point to confirm this.