[Jeddostotle7]

Quote:

Originally Posted by En Sabah Nerd

Nothing ever officially indicates whether or not the masks are necessary to their survival. If the masks do help then we also know they can go without them for some time and this guy was really close to his ship. The mouth piece used in Predator 2 could just as likely be medicinal given his injuries, like it's some kind of morphine mask.

The Alien/Predator (Xenopedia) wiki's page for the Bio-Mask says this:

Quote:

Originally Posted by Xenopedia

In Aliens Vs Predator Deadliest of the Species, the masks are shown also as working as a life support system, allowing the Yautja to breath easily on any world, (The Yautjas can also breath on human worlds, but have more difficulty, having to breath deeper.) It also featured a modified version allowing a human to breath in a natural Yautja environment, which would normally burn the lungs of and kill any human. Though this conflicts with Predator 2, where a human walked around unaided in a Yautja ship without being harmed at all.

The Alien Species wiki (just a wiki for any fictional alien species) page for Predators mentions that many "Expanded Universe" Predator works, like comics, books, etc. state that they need the mask, but give wildly different, contradicting reasons why, and different explanations of how well they survive in Earth-like atmospheres, ranging from "Can, with some difficulty", to "Can, but only for a week", to "Only for a very short while". It's safe to say that the only thing that indicates in the movies (which are the only things that seem to be indisputably canon with this universe) that Predators maybe have trouble breathing in human atmospheres, as far as I can tell, is the City Hunter breathing from the hand-held mask in Predator 2. And even then, as you suggested, there could be other reasons for his use of that hand-held mask.