Why is chlorine used and how was chlorine discovered?

Chlorine was discovered in 1774 by a Swedish pharmacist named Carl Wilhelm Scheele. While experimenting with hydrochloric acid, he discovered a greenish-yellow gas when he added a few drops of the acid to a piece of manganese dioxide.

Fast forward a century to the early 1900’s when the first pool ever to be sterilized using chlorine by John Wymond Miller Bunker at the Colgate Hoyt Pool (Brown University). This was a big milestone as previously pools were only filtered and pool water had to be replaced regularly.

Most people probably wouldn’t want to go swimming in a giant, germ-filled petri dish. Without modern chemistry, that’s what swimming in pools could be like. Even a quick swim in unsanitized water could expose a person to illnesses such as diarrhea, swimmer’s ear and various types of skin infections, including athlete’s foot.

However, despite the sterilizing properties of chlorine, there are a few drawbacks.

Chlorine is very volatile making it very difficult to maintain a constant safe residual level as bather load and conditions change. When too much chlorine is added to the water, swimming pools can become a pit of harmful chemicals. In fact, an over-chlorinated pool threaten swimmers’ health in two ways. First, contact with the skin can cause irritation similar to a burning sensation. Also, the gases given off by the evaporation of water oversaturated with chlorine-based cleaning solutions can enter the nose and eyes to cause severe itchiness and discomfort. Some health issues that have been associated with chlorine include cancer, asthma, birth defects, pregnancy problems, heart problems and skin allergies.

A mere 10 minutes dip in a chlorine-saturated swimming pool is enough for our skin to absorb enough chlorine to start affecting our kidneys and liver. Staying in a chlorine pool longer than 30 minutes may affect your brain.