The gases that surround us are called "atmosphere." Planets without air can still have an unbreathable atmosphere.
In space there is no atmosphere, so what surrounds a person is called "space" or "vacuum."
Underwater is not called an atmosphere either because it's liquid instead of gas.
What I'm searching for is a word that means "the molecules directly outside our bodies." Whether they are gas, liquid, breathable, or extremely sparse/non-existent.
EDIT: this isn't an answer, but a more boiled down description -- "immediate molecular environment" is what I'm trying to get into a word