Ammonia is some nasty stuff. I was working at a shipyard one time and doing some repairs on a barge that had been carrying ammonia. Somehow some of it got in a wing tank and just stepping over the access hatch that was opened to ventilate the space almost caused me to pass out. It’s one of those nasty one step and your down kinda things. Good luck ISS folks. Not like you can step outside or anything either. :>}
It’s a really, really good refrigerant though.
A refrigeration contractor I knew drove around in a van with an I Heart Ammonia logo on it.