Anyone who spends a relaxing day in a swimming pool without goggles is probably resigned to the uncomfortable after effects: Red, stinging eyes with cloudy vision, and possibly some chest irritation and coughing if the pool is indoors. You probably attribute this to the chlorine in the water, but that’s only half-true: The cause of your red, irritated eyes is actually the pee, sweat and (yes) even fecal matter contaminating the pool.
It’s true that chlorine is added to pools to kill dangerous germs. In that regard, it’s something of a miracle chemical – it’s effective within a few minutes, and is totally harmless to humans in the doses used in properly treated pools.
However, the problems arise when swimmers dive in with less than clean bodies. Any sweat, urine or other bodily fluids interact with the chlorine, causing the chemical reaction that irritates your sensitive tissues. Really, it’s kind of a lose-lose: Not only does the chemical reaction cause irritation, but it also caused the chlorine to lose its power, making it ineffective at snuffing out the germs it was intended for.
Particularly dangerous is entering the pool with diarrhea. Some of the germs found in feces, particularly Crypto, are especially resistant to chlorine. Toddlers and other young swimmers are typically the culprits, but anyone who’s had diarrhea recently could carry the germs on their bodies.
Because swimming is such a healthy activity, the CDC encourages it provided people take some precautions. Always shower before entering a pool, and never swim if you’re sick or have an open wound. Ever hour, everyone should exit the pool to allow the chlorine to work its magic, and even though the chlorine is generally safe, ingesting pool water should be avoided if at all possible. And obviously, never pee in a pool.
Enjoy the pool this summer, everyone.