Do Swimming Pools Trigger Asthma?

Most people spend time in or around chlorinated swimming pools during summer. It’s like a modern staple of vacations and warm summer days. As adults, sometimes we swim with the kids. And sometimes we just lie back in beach chairs and relax. As an allergic asthmatic, sometimes I find this induces sinus and asthma issues - sometimes not. So, what’s the deal?

Why do pools trigger allergy and asthma symptoms?

First of all, a majority of pools have chlorine in them. This is necessary to remove bacteria and other germs. It’s needed to keep the water clean. It’s the chlorine that gives off that strong smell that sometimes emanates around indoor pools. This is what we’ve been told for years.

But, not so fast.

Modern researchers now say it’s not the chlorine that you smell around pools. And it’s not the chlorine that causes these symptoms. It’s chemical reactions that occur when chlorine comes into contact with organic matter.^1-2

The organic matter that I’m referring to is sweat, dirt, pee, and poop. When these things enter the pool water, they react with chlorine. This causes chemical reactions that emit gases into the atmosphere.

It’s these gases that create that strong chlorine smell, not the chlorine itself. Likewise, it’s these gases that cause allergy and asthma symptoms, not the chlorine itself.

Some people theorize that the stronger the chlorine smell around pools the more chlorine was put into it. Sure, this may hold true for some pools. But, according to this new evidence, the stronger the chlorine smell around pools the more urine is put into it.

So, this might explain why you only sometimes smell that strong chlorine smell. It may explain why you only sometimes experience allergy and asthma symptoms around pools.

It’s most likely to occur in community pools where lots of people of all ages swim. It’s also more likely to occur around indoor swimming pools. Outdoor swimming pools have far better ventilation.^1-3

And it's not just swimmers. Any person who spends time around a pool (particularly large, public indoor pools) is at an increased risk of asthma and allergy symptoms. This includes workers.²

So, what do these chemicals do to airways?

These chemicals are not allergens, so you can't be allergic to them. However, they can irritate cells lining your respiratory tract and sinuses. They are easily aerosolized. They are inhaled and impact cells lining your airways and sinuses.

In those of us with a predisposition to allergies and asthma, our immune systems respond to these chemicals. They release their own chemicals, called inflammatory chemicals. These inflammatory chemicals cause inflammation of cells lining your sinuses and airways. (This also happens to your eyes, causing red-eye.)

This inflammation causes allergic rhinitis. This is why your head feels stuffy. It’s why you sniffle and sneeze. It may even explain those chlorine headaches we get. It may also cause asthma symptoms, such as chest tightness and shortness of breath.

Can these symptoms be prevented?

The CDC highly recommends that people take showers before entering pools. They recommend people not enter pools if they have diarrhea. And they recommend that parents give children breaks from the water every hour or so. They recommend for parents give their kids bathroom breaks. These are attempts to prevent organic material from getting into the pool. It's to prevent them from interacting with chlorine to produce those unwanted gases in the air around pools.⁴

The American College of Allergy, Asthma, and Immunology (ACAAI) recommends we do our part too. They suggest we work with our doctors to obtain good control of our allergies and asthma. This way pools are less likely to trigger symptoms.⁵

So, the idea here is that, with proper care of pools, people with allergies and asthma shouldn't have to miss out on all the pool fun.