Air continuously blows out from your skin, at all times. You clothes billow outward, and you learn to wear loose meshes. You also learn not to sit in enclosed spaces too often. Over the course of your life the effect on the atmosphere is negligible. Swimming is a nightmare you just look like an alka-seltzer tablet the whole time.
Thinking about the science of this...wouldn't I just sink through the air around me and to the bottom of the water because my body isn't displacing any of the water?