It's not just an old wives' tale -- too much time in the pool really can
change the color of your locks, especially if they're very light, Jessica Wu, M.D., author of Feed Your Face
tells The Huffington Post.
But it's not due to the chlorine. Instead, it's likely because of copper lurking in pools
where the chemical balance isn't quite right, according to WebMD. "The chlorine molecules get trapped in the hair and oxidize the metals found in trace amounts in the water," Jessica J. Krant, M.D., board-certified dermatologist and assistant clinical professor of dermatology at SUNY Downstate Medical Center, writes to HuffPost in an email. "It's the oxidized copper that is actually the cause of the green color."
Chlorine can still damage hair, though. "The outer layers of the cuticle of the hair -- which are like shingles on a roof -- start to lift up," says Wu. "When the outer layers lift up, then [chlorinated] water can get into the center of the hair and make your hair more brittle." Swimmers may find their hair breaks more easily in the summer, especially if it's dyed or straightened, she says.
Luckily, there are a few simple ways to prevent the damage. The easiest can be done anywhere -- just rinse your hair under tap water before taking the plunge. "Plain water binds to the hair, making it harder for chlorine to get to it," says Wu. A leave-in conditioner will have a similar effect, and can be a good pre-pool option as well. A weekly hair mask can help repair the damage and seal the cuticle, she says.
The American Academy of Dermatology also recommends wearing a swim cap
and washing with shampoo and conditioner specifically formulated for swimmers to replace lost moisture.