Green Hair Caused by Copper, Not Chlorine — Myth Busted

Swimmer wearing a swim capSwimmers, especially blondes, may be surprised – and even horrified – to discover that frequent pool use imparts a greenish hue to their hair. Typically chlorine in pool water is named as the culprit, sending the green-haired swimmer in search of products to remove the unwanted color or at least in search of a swim cap.

The green hair-chlorine connection is a firmly embedded myth: Almost half of respondents to our 2012 swimmer survey agreed that chlorine in the pool can turn hair green. We would like to expose this urban legend at its roots and offer an explanation of how it might have grown.

Copper, Not Chlorine, is Responsible for Green Hair

Green hair is caused by the presence of copper, not chlorine, in swimming pool water. Copper sulfate, for example, is added to pools to help control algae. Tiny particles of this greenish-blue compound can turn blonde or white hair green. Copper may also be leached into pool water from metal plumbing or from copper ionizer equipment and form copper sulfate in the water. One research study titled “The Green Hair Problem1” concluded that hair that had been extensively damaged–either by harsh cosmetic treatment or by exposure to sun and weathering–showed the highest degree of green coloration from absorbed copper.

To avoid an unwanted green tint:

  • Wear a swim cap, or
  • Use a shampoo formulated to help remove copper (yes, they exist) after swimming.

We suggest there could be a semantic reason for the chlorine/green hair linkage. The root “chloro” is Greek for “green.” Chlorophyll, for example, is the organic compound in plants that absorbs sunlight and lends a green color to leaves. In 1810 the chemical element chlorine was named for the greenish color of its gas. Nevertheless, chlorine does not impart a green color to pool water.

Chlorine is added to pool water to destroy bacteria, viruses and parasites in water that would otherwise put swimmers at risk for disease. Most chlorine is added to pool water in the form of compounds of chlorine that are either white solids or colorless liquids. Although some pools are designed to bubble chlorine gas into the water, the greenish chlorine gas reacts quickly with pool water to produce dissolved “free chlorine,” which is colorless.

Chlorine is a well-known pool chemical and its name implies the color “green.” We think it is conceivable that those two factors together helped shape a myth linking chlorine and green hair. Hopefully we have helped expose the roots of this myth and untangled the truth. Happy swimming!

1Bhat, G.R., Lukenbach, E.R., Kennedy, R.R. and Parreira, R.M. (1978). The green hair problem: A preliminary investigation, J. Soc. Cosmet. Chem., 30, 1-8.