Like many people who swim in the summer, you might have assumed it's the chlorine that makes your eyes so red in pools.
"When we go swimming and we complain that our eyes are red, it's because swimmers have peed in the water," Michele Hlavsa, chief of CDC's healthy swimming program, told "Today."
The CDC also said in its report that the chlorine smell of pools isn't actually what you think. "What you smell are actually chemicals that form when chlorine mixes with pee, poop, sweat and dirt from swimmer's bodies... These chemicals -- not chlorine -- can cause your eyes to get red and sting, make your nose run, and make you cough."
"Yuck!" the CDC concluded.
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