"Dirty socks" is commonly how fume events on aircraft are described to smell, which is when oil from the engine makes it into the air conditioning system. The

"Dirty socks" is commonly how fume events on aircraft are described to smell, which is when oil from the engine makes it into the air conditioning system. The health effects aren't fully understood, with claims ranging from them being harmless to causing severe neurological defects https://en.wikipedia.org/wiki/Fume_event https://en.wikipedia.org/wiki/Fume_event