There's a warning on the Torchmate site which talks about an explosion hazard from dissociated hydrogen that can accumulate under a sheet of aluminum as it's being cut: https://torchmate.com/uploads/images...fetyNotice.pdf
Apparently the hot aluminum has a big affinity for oxygen, and it can grab some away from the H2O molecules, creating free hydrogen. But if you're not doing multiple sheets in a short period of time, it's probably not a huge issue.
There's also a problem with aluminum-lithium alloys, which can burst into flames when they hit water.
But in general, I think it's safer than cutting stainless steel, which releases hexavalent chromium. http://www.esabna.com/us/en/educatio...hex-chrome.cfm That's a very nasty, irritating and carcinogenic substance you need to protect yourself from by using a dual-cartridge or air-supplying respirator https://www.red-d-arc.com/pdf/MSA%20...Protection.pdf as well as good ventilation and the proper eye, skin, and hand protection equipment.