It’s Not Chlorine That Turns Hair Green in Pools. Here’s The Actual Explanation

If you’re a frequent swimmer, especially if you have blonde hair, you may have noticed a green tint in your hair after swimming in chlorinated pools. The common belief is that the chlorine in the water is responsible for this discoloration. However, the reality is quite different. In this article, we’ll explore the actual explanation behind why hair turns green in pools and debunk the chlorine myth.

The Culprit: Copper, not Chlorine

Contrary to popular belief, it’s not chlorine that turns hair green in pools; it’s copper. Copper sulfate (CuSO₄), a compound added to swimming pools to prevent the growth of algae, is the primary source of copper. Even though only a small amount of copper sulfate is needed to achieve this purpose, copper can also enter pools through water pipe corrosion, leading to higher concentrations in some pools.

When hair comes into contact with copper ions, which are positively charged variants of copper atoms with extra electrons, these ions get absorbed by the hair, resulting in a greenish hue. While the green discoloration is more visible on light-colored hair, damaged hair, such as that caused by bleaching or exposure to the sun, is more susceptible to copper ion binding due to broken bonds within its structure.

Scientific Studies on Green Pool Hair

The phenomenon of green pool hair has intrigued scientists for several decades. In a groundbreaking study conducted in 1978, researchers immersed hair samples in water containing varying concentrations of copper ions, chlorine, and different pH levels. The results revealed that hair exposed to free copper ions turned green, while hair submerged in water with chlorine but without copper ions did not exhibit any discoloration. This study established copper as the primary cause of green pool hair.

Further research teams have investigated how copper ions attach to hair using sophisticated techniques such as scanning electron microscopy. These studies demonstrated that copper ions bind to various chemical groups present in hair, particularly the disulfide groups. Interestingly, other metal ions like zinc, lead, chromium, and mercury also have the ability to bind to hair in a similar manner.

Preventing Green Pool Hair

Now that we understand the role of copper in turning hair green, let’s explore some preventive measures you can take to avoid this issue:

1. Physical Barrier: Swim Caps

Wearing a swim cap is a simple and effective way to create a physical barrier between your hair and the pool water. By keeping your hair protected from direct contact with copper ions, you can minimize the chances of it turning green.

2. Chemical Pre-treatment: Alkaline Shampoo

Another option is to pre-treat your hair with an alkaline shampoo before swimming. Research has shown that under alkaline pH conditions, copper ions are less likely to bind to hair. You can choose a shampoo with a pH lower than 7 or even mix some baking soda into your regular shampoo for an alkaline effect.

Treating Green Pool Hair

If your hair has already turned green from swimming in pools, don’t worry! There are ways to remove the green discoloration:

1. Chlorine Removal Shampoos

Shampoos specifically designed to remove chlorine from hair can also help eliminate the green hue. These products often contain a chemical called EDTA, which binds to metal ions like copper and helps remove them from the hair.

2. Tomato Sauce or Ketchup Myth

You may have heard that using tomato sauce or ketchup can help neutralize the green color in your hair. However, there is no scientific evidence to support this claim. It’s best to rely on chlorine removal shampoos or seek professional advice for effective treatment.


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