WHAT: A three-minute video explaining the chemical reactions that happen when you pee in a swimming pool.
WHO: The American Chemical Society's "Reactions" YouTube channel, writer/producer Kirk Zamieroski.
WHY WE CARE: There are still several weeks of summer left, and given the unpredictable weather here in 2016, there could be even more very hot days to come, which means that swimming is still very much on the radar. But while it's refreshing to hop in the pool to cool off, one of the things that people swimming in public pools must do as they get in is willfully pretend that they aren't also jumping into a body of water that contains a whole bunch of strangers' pee. That's gross for the obvious reasons, and peeing in a pool is definitely not a socially acceptable way for an adult (or even a child who has been raised by adults) to behave. However, it's not just bad because you're making other people splash around in your urine—as the PSA from the American Chemical Society explains, the chemical reactions that occur between the chlorine and other pool disinfectants and urine can be hazardous. The disinfection byproducts that are created when our biological material combines with those chemical agents are not great—they range from red eyes to respiratory problems like asthma. As straight guilt-trips go, this one is designed to both educate and make you feel bad if you ever pee in a pool again—which, it points out, is common: pools average 30-80 ml of urine per swimmer. Eww.