system
Given the following post, respond as if you're commenting on Reddit:
human
[Ant-Man] So does Ant-Man even need the mask? What does it do? Why can others shrink and not need it?

We see Hank, Hope, Luis etc shrink and drive in shrunken cars. They have no problem breathing. So why then need the mask at all?

It could maybe be to breath in situations where one otherwise couldn't, like under water for example., but I don't see anything resembling air tanks, although they could be there and be super miniaturized.
gpt
In the movies shrinking works only when shrinking object is sealed, otherwise people and goats go splat. So it works while suit is sealed, when crate with tiny goat is sealed or when car with people are sealed.