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Pool chlorine and eyes


Illustration of children having fun swimming in the pool

Recently, more and more people go swimming and gym and swim in the pool.


Swimming has many positive aspects for good health.


On the other hand, you may get infections such as pool fever (pharyngoconjunctival fever), hand-foot-and-mouth disease, water drops, and epidemic keratoconjunctivitis.


Therefore, "chlorine" is added to the pool water to weaken the power of pathogens.

This "chlorine" is a chlorine-based disinfectant that, when dissolved in water, produces hypochlorous acid (free chlorine), which is effective.


It is well known that the chlorine in the pool causes the eyes to bleed, the skin to become dry, and the hair to hurt.

The pool is designed to keep the free chlorine concentration between 0.4 and 1.0 ppm (in Japan).


On the other hand, drinking water is determined to be 0.1ppm or more (in Japan), and in high places, it may be 2ppm or more.


However, tap water does not smell as chlorine as a pool and is less irritating to the eyes and skin.


Why is that?

In addition to free chlorine, chlorine (residual chlorine) dissolved in pools and tap water includes what is called bound chlorine, which is also known as "chloramine" and has a low disinfecting effect and is irritating. Has the property of being strong.


This combined chlorine is produced by the reaction of free chlorine with the ammonia compounds dissolved in water by sweat, body stains, urine, cosmetics, hair styling products, and detergents attached to swimwear.


In other words, even if there are no bacteria or viruses in the water, the stains on the water will reduce the disinfecting effect of "chlorine" and increase the irritation.


In addition, when free chlorine is converted to combined chlorine, the concentration of free chlorine decreases accordingly, so it is necessary to add a chlorine-based disinfectant.

Therefore, water and pools have the same concentration of free chlorine, but the concentration of harmful bound chlorine is quite different.


In addition, when free chlorine is close to 1.0ppm, the irritation to the cornea becomes stronger and it may cause inflammation. It is recommended that you use goggles when swimming and wash your eyes with preservative-free tear-type eye drops after getting out of the pool.


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