Blonde hair can turn green in swimming pools due to a chemical reaction between the hair's natural melanin and the chlorine or bromine used to disinfect the water. Melanin is a pigment that gives hair its color, and when it is exposed to chlorine or bromine, it can oxidize and turn green. The higher the concentration of chlorine or bromine in the water, the more likely it is that blonde hair will turn green.
Green hair is not harmful, but it can be unsightly. There are a few things that can be done to prevent or remove green hair, such as using a clarifying shampoo, swimming in a pool with a lower concentration of chlorine or bromine, or wearing a swim cap.
