Gray hair is characteristically more wiry, coarse and dryer than non-gray hair. As hair turns gray, the strands thicken and become brassy, white or gray. Hair turns gray because as you age melanocytes start to diminish in the hair follicle. Melanocytes are the tiny cells that produce hair pigment or color. Melanocytes also help protect hair from damage from substances such as chlorine in swimming pools.
Dry and Brittle
Chlorine dries out gray hair. Chlorine is a chemical oxidizer, which depletes the hair of proteins that keep the follicles plump and healthy. This can make your gray hair feel like straw when it is dry. Chlorine in wet gray hair makes your hair feel gummy or mushy.
Gray hair can become brittle if exposed to chlorine regularly. When hair is brittle, it breaks and may look frizzy and fly away. Keeping your hair in a short hairstyle and using a wide tooth comb to gently style hair can prevent breakage.
Color Changes
Chlorine oxidizes your hair and may cause the hair to lighten in color, especially when exposed to sun and wind afterward. Gray hair may turn a brassy or dull yellow-gray instead of a solid neutral gray due to chlorine oxidization.
Gray hair exposed to chlorine will lose its shine and become dull. The chlorine oxidizes and roughs up the cuticle, which makes the hair appear dull.
If you have any hair color in your hair to cover your gray; the chlorine may bleach it out or remove it. More frequent touch-ups to cover your gray hair may be necessary.
Chlorine does not cause hair to fall out. A study reported in the New York Times says that hair exposed to chlorine will get dry and damaged, but does not cause it to fall out any faster or in higher quantities than normal hair.
Gray hair does not turn green due to chlorine, but it can turn green from other chemicals in swimming pools. Copper and rust will sometimes leach into swimming pool water from corrosion of pipes or added chemicals; these are often the cause of green hair from swimming.
Prevention
Protect gray hair from chlorine by shampooing and conditioning it immediately after swimming. Wear a swim cap when you swim. Put a hair conditioner on your hair before you swim to protect the hair follicle and prevent chlorine from being absorbed.