Breath communicates significant signals, and the handshake-eye rub experiment demonstrates that humans reflexively engage in behaviors to smear themselves with others' chemicals.

“You might say, "Well, I don't actually go around sniffing people's breath. I don't, you know, unless if it's bad," in which case it's aversive, but breath is communicating a lot of signals. And this handshake eye rub experiment shows that we are actively going through behaviors reflexively to wipe ourselves or smear ourselves with other people's chemicals.”