That Isn’t Chlorine You’re Smelling In The Pool

“Water is a very good servant, but it is a cruell maister.” —William Bullein, “Bulwarke of Defence against All Sicknesses”

In A Nutshell

Nothing says summer like the smell of chlorine from a pool . . . but it’s not chlorine you’re smelling. It’s chloramine, a chemical produced by the reaction between chlorine and urine. And it’s what makes your eyes red. When people think it’s okay to stay in the pool for bathroom breaks, pools become a massive, festering slush of disease, with everything from asthma and lung infections to Legionnaires’ disease associated with swimming in dirty pools.

The Whole Bushel

There are a lot of things we associate with the summer months, from the smell of a backyard BBQ to the drone of bees and the flickering of fireflies at night. Our sense of smell helps us form some of the strongest memories and associations, and the smell of chlorine from the neighborhood pool just screams summertime. It’s unmistakable, pungent, and eye-watering, promising sun, fun, and sunburns.

But it turns out that’s not exactly what you’re smelling.

The smell comes not from the chlorine itself but from the reaction that happens when chlorine goes to work getting rid of all the nasty stuff that no one really wants to admit are in every public pool: sweat, dirt, urine, and feces.

The chemical produced in the reaction, called chloramine, is what makes your eyes red, too. Chloramine is a derivative of ammonia and occurs when urine and chlorine bind to create something new.

But, people might ask, isn’t the point of chlorine to disinfect the pool and get rid of germs and all the other nasty things in there?

That’s true, but there’s a time delay between the time a foreign substance enters the pool water and the time it take both chlorine and bromine to kill it. Germs can be floating around for a few minutes before the pool chemicals do their thing. It also creates another problem: When chlorine combines with things like urine, the chlorine gets used up so it can’t fight off other kinds of germs.

Some types of germs—like the parasitic Cryptosporidium—can survive up to 10 days even in water that’s properly treated with chlorine and other chemicals. From 2011 to 2012 alone, there were more than 1,780 cases of the parasitic disease that cropped up in connection with pools. The disease is spread through diarrhea and can continue to spread for up to two weeks after symptoms have disappeared, well into the time frame most people would think it’s safe to head back into the water.

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The Centers for Disease Control and Prevention stresses that it’s a big problem in public pools around the country. The CDC’s water safety guide urges people to quit peeing in pools.

Also important? Don’t drink the water.

As if that isn’t gross enough, a whole host of other dangers come with swimming in public pools where hygiene is an afterthought. Chloramine has been linked to a number of respiratory disorders, and some studies have suggested that kids who swim in unhealthy pools have the same risk levels for developing asthma as smokers do.

Indoor pools are associated with cases of Legionnaires’ disease, characterized by fever, muscle aches, difficulty breathing, and headaches. As many as 50,000 cases are reported every year in the US alone, and they’re caused by breathing the germ-ridden water vapor of indoor pools. There are also things like lung and skin infections, swimmer’s ear, and athlete’s foot, with one study even linking the water in public pools to DNA mutations and cancer.

Show Me The Proof

Washington Post: Scientists describe the gross reason why your eyes sometimes sting, turn red in swimming pools
Medical Daily: Feces In The Water And 5 Other Health Risks Of Swimming In Public Pools
Centers for Disease Control and Prevention: Share the Fun … Not Germs
LiveScience: ‘Crypto’ Parasite Outbreaks Increasing in Pools Across US

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