Why Hair Turns Green in the Pool and How to Fix It

Swimming is a popular activity, but many swimmers notice an unpleasant side effect: their hair turns green from the pool. It’s most noticeable if you are blonde, but even dark hair suffers damage and color change. This discoloration is often mistakenly attributed to chlorine, but the actual culprits are other chemicals in the pool. This article explores why hair turns green, the chemistry behind it, prevention methods, and ways of remedying the discoloration.

• Blonde hair turns green from the pool because of the copper, not the chlorine or bromine.
• However, chlorine and bromine cause oxidation and damage hair, bleaching it and making it susceptible to copper deposition. The bleaching affects dark hair, too.
• High porosity hair loses color. Dark hair gets more yellow. Light hair gets less yellow.
• UV from the Sun also damages hair and makes the effect that much worse.
• Prevent or minimize the effect by wearing a swim cap or at least thoroughly wetting your hair before getting into the pool.
• Remove the green color using an alkaline ingredient, like baking soda, but then thoroughly condition hair.

The Chemistry of Why the Pool Turns Hair Green

The green tint in hair after swimming is primarily caused by copper compounds in the pool water. Here’s a detailed look at how this happens:

1. Copper Sources: Copper enters pool water through various sources:
   • Algicides: Many algicides contain copper sulfate.
   • Plumbing: Corrosion of copper pipes and fittings releases copper into water.
   • Pool Fill Water: Some municipal water supplies contain trace amounts of copper.
2. Chlorine’s Role: While chlorine itself doesn’t cause green hair, it plays an indirect role by oxidizing copper:
   • Oxidation: Chlorine reacts with copper, forming copper (II) chloride and other oxidized copper compounds.
   • Attachment to Hair: These oxidized copper compounds bind to the proteins in the hair shaft, particularly keratin, which results in a greenish tint.
3. Bromine’s Role: When a pool uses bromine instead of or in conjunction with chlorine, the effect is the same. Bromine is an oxidizer that damages hair and makes it more porous.
4. Ultraviolet Light: Ultraviolet (UV) from sunlight also breaks bonds in hair. Even if the pool lacks chlorine or bromine, sun exposure makes hair susceptible to copper.

Mechanism of Hair Discoloration

Hair consists of keratin, a protein rich in sulfur-containing amino acids. These amino acids have a high affinity for metal ions, including copper. When copper ions are present in the pool water, the hair shaft absorbs them, particularly when the hair cuticle (the outermost layer) is damaged or lifted. Copper preferentially binds to oxidized disulfide bonds (cysteic acid). The copper not only imparts a blue-green color, but also reduces shine and smoothness. The following factors facilitate this process:

• Porosity of Hair: Damaged or chemically treated hair is more porous and prone to absorbing copper ions.
• pH Levels: Lower pH levels open the hair cuticle, making it easier for copper ions to penetrate.
• Chemical Reactions: Once inside the hair shaft, copper ions react with other compounds, forming green-colored complexes that become trapped in the hair.

Preventing Hair from Turning Green

Prevention is key to avoiding green hair. Here are effective methods:

1. Pre-Swim Rinse: Wetting hair with fresh water before entering the pool reduces its ability to absorb chlorinated water.
2. Protective Hair Products: Use leave-in conditioners or specially formulated pre-swim hair treatments that create a barrier on the hair shaft. Ideally, seek a product that also blocks UV rays.
3. Swimming Caps: Wearing a swim cap provides a physical barrier, keeping chemicals in water away from hair.
4. Regular Pool Maintenance: Keeping copper levels in the pool water low through regular testing and appropriate chemical treatments minimizes copper absorption by hair. Maintaining optimal pH helps, too.
5. Shower After Swimming: Rinse hair immediately after swimming to remove any residual pool water.
6. Avoid Prior Damage: Bleaching, waving, or relaxing your hair increases the amount of cysteic acid and other anionic sulfonate groups in hair. Basically, it makes you hair more susceptible to copper deposition.

Removing Green Color from Hair

If you already have green hair, several methods help remove the discoloration:

1. Chelating Shampoos: These shampoos remove mineral buildup, including copper, from the hair.
2. Home Remedies:
   • Baking Soda Paste: Mix baking soda with water to form a paste, apply it to the hair, let it sit for a few minutes, then rinse thoroughly. Baking soda (sodium bicarbonate) is a common household base. Its high pH helps copper ions release from hair.
   • Lemon Juice or Tomato Juice: The acidity helps clarify hair and neutralize the green tint. Apply to hair, leave for 10-15 minutes, then rinse out.
   • Aspirin Solution: Dissolve a few aspirin tablets in water, apply the solution to the hair, and let it sit for 15-20 minutes before rinsing. Aspirin is a weak acid, so it works much like fruit juice or vinegar.
3. Vinegar Rinse: A rinse with diluted white vinegar or apple cider vinegar (one part vinegar to four parts water) helps dissolve copper buildup.
4. Counter Color: Red, red-orange, or pink hair dye neutralizes the green color. Add some to your conditioner and counteract the green color.
5. Professional Treatment: For severe cases, visit a professional salon for specialized treatments.

Remedying Hair Damage

Pool water damages. Here’s how to restore hair health:

1. Deep Conditioning Treatments: Use deep conditioning masks that restore moisture and repair the hair shaft.
2. Deposit Color: Depending on your original hair color and ethnicity, the pool strips some color. Consider using a semipermanent dye that fills in the missing pigment without causing more damage.
3. Protein Treatments: Strengthen the hair with protein treatments that repair damage and reduce porosity.
4. Avoiding Heat Styling: Minimize the use of heat styling tools, which further damage already weakened hair.
5. Trim Regularly: Regular trims remove damaged ends and keep hair looking healthy.

References

• Arnaud, C.H. (2016). “The chemical reactions taking place in your swimming pool.” C&EN. 94:31.
• Blanc, D., Zultak, M. et al. (1988). “Green hair: clinical, chemical, and epidemiologic study. Apropos of a case.” Ann. Dermatol. Venereol. 115(8): 807-812. PMID: 3202580
• Pires-Oliveira, R.; Joekes, I. (2010). “Hair color damages caused by exposure to chlorinated water in the presence of ultraviolet radiation.” 26th IFSCC Congress.
• Robbins, Clarence R. (2012). Chemical and Physical Behavior of Human Hair (5th ed.). Springer-Verlag. doi:10.1007/978-3-642-25611-0
• Tomas, X.; Nogueras, M.; Bartolome, A.; Ferrando, J. (2022). “Pseudo Green Hair.” Int. J. Trichology. 14(2): 65-67. doi:10.4103/ijt.ijt_134_20
• Wu, Amber (2018). “The Effects of Chlorine on Different Ethnicities of Hair.” Posters At-The-Capitol.