Even though Chlorine is an excellent disinfectant more than iodine, it is still bad for your hair as well as your scalp and skin. Chlorine is a strong oxidizing agent which is an irritant as well as drying agent. In small quantities in drinking water, chlorine may not be harmful.
But in bacteria breeding swimming pools, chlorine is used in larger quantities to kill bacteria such as e-coli and for other hygienic purposes. Hair can become brittle and dry since chlorine can take away the greasy and oily surface layer of your hair known as sebum making your hair dry and susceptible to crack, and taking away the sheen of your hair. The unprotected hair cortex can become split causing split ends. It can also damage your scalp and skin too.
In order to prevent damage to your hair from chlorine, wearing a latex or silicone cap while swimming, applying a conditioner to hair before a swim, and soaking your hair and body before jumping into the pool can help you to minimize damage from chlorine. Go light on hair coloring, perms, curlers and blow dryers. When drying your hair, do not rub, just pat dry, squeeze gently and wrap a towel around your hair.