The Centers for Disease Control and Prevention has revealed the real reason why swimmers' eyes burn in the pool.
Most people believe that chlorine causes red and stinging eyes when swimming, and while that's not completely false, there's another gross element to blame: urine, sweat and other waste.
"Irritants in the air at swimming pools are usually the combined chlorine-by products of disinfection. These by-products are the result of chlorine binding with sweat, urine, and other waste from swimmers," a report from the CDC said.
FOX 59 reports these irritants tend to be stronger in indoor pools, where they can contribute to poor air quality.
"As the concentration of by-products in the water increases, they move into the surrounding air as well," the report said.The lack of air circulation can cause further irritation for swimmers, such as red eyes and stinging.
For better air circulation, doors and windows should be kept open, according to the CDC.
Also, to decrease the formation of irritants, swimmers should shower and use the bathroom before getting in the pool.