In prior forum discussions, people have said that the way to know if one is in a vacuum or not is if one loses oxygen or not. So in some places it’s obvious – Iwajira clearly in a vacuum. But others, it’s somewhat confusing. For instance – in the Titan Robot Production plant, one doesn’t lose oxygen but enemies drop those blue O2 canisters like crazy? Seems the same for the Sentinel arena (O2 container drops but not losing oxygen on the meter).
Then there’s the question of WHO is in vacuum or not (self or enemy). In the Holodome, e.g., you could be in an air bubble and the enemy not – which bonus do you get?
Wish this were clear to me & don’t know who I’d believe without actual testing. Just today saw a duality kit that gives “increased incendiary damage in a vacuum”! WTF – thought fire was a no-go in a vacuum?