This is the 3795th most frequent German word.
sauber
Clean.
Here, 'sauber' is used as an adjective to describe the state of cleanliness of the room.
Das Zimmer ist sauber.
The room is clean.
In this context, 'sauber' is utilized as an adverb to describe the individual's meticulous manner of working.
Er arbeitet sehr sauber.
He works very neatly.
In this usage, 'sauber' acts as an adjective describing the freshness or cleanliness of the air.