Short-term exposure to chlorine may cause dryness for bleached or color-treated hair. Long-term and regular exposure to chlorine does cause bleached or color-treated hair to have adverse reactions. Chlorine does not cause bleached or color-treated hair to turn green.
To prevent chlorine damage, saturate your hair with clean tap water prior to swimming; this reduces the amount of water your hair absorbs in the pool. Wearing a swim cap also provides protection from chlorine. The best way to prevent chlorine damage is to shampoo your hair with a clarifying shampoo or shampoo that is especially designed to rinse away chlorine after exposure.