A word for both surrounding gases and liquids (or absence of)?

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