When pee mixes with chlorine, it forms chemical irritants called chloramines, which can not only corrode metal but can cause bodily ailments like puffy or stinging eyes, itchy throat, coughing and rashes, according to the above video from SciShow. Sweat, dirt and dead skin cells can also bind with chlorine to create chloramines, according to the Centers for Disease Control and Prevention. These chemicals are the reason many swimmers and lifeguards experience respiratory irritation after spending time at the pool. And yes, this is true for salt water pools, too ― they still contain chlorine.
While chloramines won’t kill you, they’re one more really, really good reason to relieve yourself indoors instead. Watch above for the full breakdown.