Swimming is one of the highest profile sports at the Olympic Games, with dozens of athletes competing at the London 2012 Olympic Games alone. However, even though we can’t all be top-flight athletes, most of us at some point in the year slip into our best swimming costume, and have a dip in the pool. But whether it’s endless lengths of butterfly, or just a quick dip with a cocktail in hand, there is one thing in common that you can clearly sniff out -- chlorine.

It’s there for very good reason, chlorine-based treatments are vital to make sure that the water we swim in is clean and protected from bacteria and algae. One of the most common treatments is based on sodium hypochlorite, which is added to pools at very defined, and surprisingly small levels. In fact, the average chlorine level in a pool is around 2 parts per million -- think of that as 18 people out of the whole population of Greater London.

But apart from leaving you and your hair smelling faintly of bleach -- even though it’s only present in minute quantities -- chlorine can have some detrimental effects on your hair.  So not only do swimming caps make you more aquadynamic, they can also help to protect your hair, too.

Chlorine: The Science Bit
The effects on hair of water containing chlorine were first studied way back in 1916, by a scientist called Allworden. His experiments demonstrated that hair becomes oxidized when exposed to chlorine, which in turn resulted in a breakdown of hair’s protein structure. However, his experiments were carried out at much higher concentrations than those found in typical pool water. 

More recent research carried out by Fair and Gupta, which showed that even at such low concentrations, the presence of chlorine resulted in increased surface roughness.  This means that the hair not only felt rougher, it was more difficult to comb and was significantly less shiny.  The magnitude of the effect was dependent on the amount of exposure – so the more time you spend in the pool, the bigger the effect that you can expect to see.

It is still unclear exactly what is going on deep inside the hair fiber, however it is believed that the changes involve the fundamental bonds between the amino acids that hold hair’s structure together.  In addition it is also believed that chlorine softens and lifts the cuticles, hair’s natural protective layers.

The problem becomes even more important for those of us with color-treated hair.  A study published in the Journal of the Society of Cosmetic Chemists (yes, really) has shown that hair colored after being exposed to chlorine is more susceptible to further damage.

The Mystery of ‘Green Hair Syndrome’
Many regular pool-users, especially those with blonde or bleached hair, often complain that their hair starts to take on a slight greenish tinge. The green color observed is suspiciously similar to the color of chlorine, which gets its name from the ancient Greek for pale green, and so it was often blamed on chlorine being absorbed into the hair. 

However this is somewhat of a red-herring (or should that be green-herring).  In fact the green color observed is nothing to do with chlorine, but due to the presence of copper, which is used in algaecides, added to the pool to stop any slimy green sludge appearing on the pool walls.

There are two main reasons why this is more common in blonde or bleached hair:

• Naturally lighter hair has less background pigment to mask the presence of the copper in the hair.
• Chemically bleached hair is more porous and can ‘suck-up’ more copper from water.

The Solution?
Well thankfully there are a number of things that you can do to help repair and protect your hair from the effects of chlorine:

Before you get in the pool:

• Before putting on your swimming-cap, run your hair under the shower to ensure that it is saturated with non-treated water.  Hair is like a sponge, so if it’s already full of water, it is more difficult for hair to absorb more water from the pool itself.  Even if you don’t wear a swimming-cap this step should be part of your pool-routine.
• A swimming-cap can really help your hair avoid absorbing more water, it forms a barrier between your hair and the chlorine and copper containing water.  This is particularly important if you have chemically treated or bleached hair, which is more porous and more vulnerable to damage.
• Put a layer of conditioner inside your swimming cap , such as Pantene Repair and Protect, and treat your hair to a workout as well as your body

After your swim / or pool-side cocktail:

• Pool-side Rinse -You can remove some of the chlorine by doing a quick pool-side rinse
• Use products such as Wella Professionals SP After-Sun Shampoo, designed to provide gentle cleansing for the hair and body, to remove residue of sunscreen, salt and chlorine water.
• Regular swimmers should also consider using deep-treatment products such as Pantene 2 Minutes Intensive Smoothing Masque, designed to give stressed hair with the conditioning it needs to look, feel and behave as good as possible.