Hydrogen is a flammable and explosive gas that is given off from most aqueous batteries. For Outdoor Enclosures where equipment and batteries are co-located the batteries will then be located in a confined volume where there will be little and poorly characterized ventilation. Several unknown factors are involved, the actual rate of hydrogen given off from the battery is a very important factor, the other decisive unknown variable is the actual ventilation levels in enclosures where no forced ventilation is installed. Through the years we have worked out strategies to qualify and safe guard the enclosures for the hydrogen peril. The authors have the opinion that there is the need for international standardisation around the hydrogen management in particular and secondly around the safety for valve regulated lead acid batteries.