Clarification regarding batteries and ups
For sealed lead acid batteries, there will be some minimum level of ventilation required; they can give off hydrogen gas which is not poisonous but mustn't be allowed to collect in an unventilated space. Not a huge problem; just ventilate it as well as you would a bathroom.

For older (maintainable) batteries - does anyone still make them? there are some precautions to be taken during battery maintenance, against acid splashes.

And of course, never carry aluminium ladders in a battery room! More realistically in your installation, all battery terminals and high current circuitry should be covered and inaccessible to anything metal except when being worked on. (Accidental short circuits can melt screwdrivers and, in a proper battery room, ladders.)

I think that's about it.