“Staying at a rented apartment, why does the vent have a green light inside it?”
Answer: "It’s likely that it could be a UV-C sterilization lamp. Kills germs/viruses as they pass by. Also, can help prevent mold and whatnot from building up on the coil."
I have one of these! In spite of what I thought when I first saw it at a garage sale it's comfortable beyond belief. I can sit on it for a couple of hours and get up with no trouble at all.
don't blame you, he got tatts and has no idea what they are?