Minimize the Risks of Swimming in Chlorinated Pools

Last summer one of my kids' favorite activities was swimming with friends at a local pool. So this summer I decided to fork over the money for a pool membership. Which means I am committing to taking my kids swimming frequently in order to get my money's worth. But the pool is chlorinated, as most are, and swimming in chlorinated pools has certain risks. Nonetheless, I believe for my family the pros of physical activity and fun with friends outweigh the risks. Still, I'd like to mitigate those risks as much as possible. First a bit about the risks.

The Dangers of Swimming in Chlorinated Pools

Feel free to skip over this section and go straight to the strategies for minimizing the risks below. We don't all need to know the depressing details! But for those interested, here goes. When contaminants such as sweat, hair, sunscreen, or urine mix with the chlorine in the pool, they form disinfectant by-products, or DBPs. One type of DBP, chloramines, is responsible for the strong chlorine smell we associate with pools. DBPs are known respiratory irritants. Many DBPs are toxic or suspected carcinogens.

Indoor chlorinated pools create an additional danger compared to outdoor pools because of the enclosed atmosphere. I have long disliked indoor pools because of the mugginess and extra strong chlorine smell (which is actually chloramines) of the indoor air. Volatile chemicals can be transferred from water to air and then inhaled by swimmers and spectators. Outdoor pools offer greater ventilation.

Numerous studies have connected swimming in chlorinated pools to health problems, particularly for the very young and the highly exposed (for example, elite swimmers and pool workers). Health problems associated with exposure to chlorinated pools include increased risk of respiratory problems, childhood asthma and allergies, DNA damage and bladder cancer (see this discussion of the effects of DBPs). Several studies have highlighted the risks of swimming in indoor chlorinated pools in particular. For example, studies have linked swimming in indoor pools to testicular damage, as well as asthma and recurrent bronchitis in children. But the research on DNA damage and cancer is in the early stages, and the research reviews on chlorinated pool exposure and childhood respiratory problems that I read stated that the connection is inconclusive (since some studies find no connection, or even associate swimming with a decrease in respiratory symptoms).

For me, the bottom line is that toxic chemicals are present in and around chlorinated pools, and while researchers are busy studying the health effects of those compounds, my family will enjoy the benefits of recreational swimming while doing our best to mitigate our exposure to harmful chemicals.


How to Limit Exposure to Harmful Substances in Chlorinated Pools

When swimming in a chlorinated pool: 

  • If the pool where you swim smells strongly of chlorine, talk to the management. A well-maintained pool (even an indoor pool) should have little or no disinfectant odor nor cause discomfort to swimmers' lungs and eyes. If you want to check the pool sanitation status yourself, see the instructions for using test strips below.
  • Drink plenty of water ahead of time to limit absorption of pool water.
  • Rinse off before getting into the pool and encourage others to do the same.
  • Do not pee in the pool : ) According to a 2009 study (cited here), 17% of Americans admitted to peeing in the pool. Perhaps fewer would if they knew it contributed to the inhalation of carcinogens. Take children to the bathroom regularly to use the toilet and to change diapers. My daughter recently asked me if it was OK to pee in the pool. Make sure your kids know that it isn't.
  • Don't swallow pool water. When I noticed my child was going to the bathroom a ton of times while at the pool, we had a chat about keeping his mouth shut to avoid drinking pool water. 
  • Wear goggles to protect eyes.
  • Immediately after swimming, shower to remove harmful chemicals from skin.
  • Immediately after swimming, seek fresh air to remove harmful chemicals from the lungs.
  • Swim when your pool is less busy if possible. Fewer people means fewer contaminants and fewer hazardous disinfectant by-products.
  • Since vitamin C can neutralize chlorine, some folks recommend using it on hair and even skin after swimming (combine with water to form a spray). The product SwimSpray, for example, claims that it "eliminates chlorine odor and irritation from hair and skin." I also came across recommendations to take vitamin C as a supplement. However, I couldn't find any scientific evidence that vitamin C offered protection from negative health effects of exposure to chlorine and chlorine byproducts. Based on testimonials from swimmers, it probably does help remove chlorine odor and might help your skin and hair stay healthy too.

When selecting a pool:

  • Choose non-chlorinated pools if you have the option. If you don't, advocate for alternatives to chlorine in your community whenever possible.
  • Choose outdoor pools over indoor pools. Indoor pools have far less ventilation than outdoor pools and swimmers and spectators will inhale more harmful compounds. See the above section on the dangers of chlorinated pools for more details.
  • Swim at less crowded pools if possible. Fewer people means fewer contaminants and fewer hazardous disinfectant by-products.
  • Choose a pool where the requirement to rinse off before entering the pool is strictly enforced (I have seen huge variation on this).
  • Ask about the training of the pool operators. Many state and local pool codes do not require pool operators to have any training in safety, disinfection, or chemical handling. (Find a graphic about different states' requirements here.)
  • Ask the management how often the pool is tested; the disinfectant level and pH should be tested twice a day. Also note that a pool that smells heavily of chlorine is a sign that the pool is full of contaminants and hazardous chlorine byproducts and/or poorly maintained.
  • Swimmers can bring their own test strips to check the water for proper chlorination and pH levels. Free chlorine levels should be 1–3 ppm, or bromine level should be 2–5 ppm. The pH level should be 7.2–7.8. At a pH above 7.8, chlorine will not effectively kill germs. At a pH below 7.2, chlorine will actually be more effective, but swimmers might experience skin or eye irritation. If your test shows the pool isn’t properly disinfected, notify the management, and don’t swim in the pool.

Other tips:

  • Limit exposure to chlorinated pools with the youngest children. We consciously chose to wait until our first child was five to take lessons or swim regularly partly based on this study (linking early exposure to chlorinated pools to respiratory issues such as asthma later in life). But my second and third child were younger, since it's pretty tough to keep younger siblings out of the pool. This is the first summer though that we will be swimming more than once a week on average (my youngest is now 4 1/2).
  • If respiratory problems such as asthma symptoms worsen on days you swim, disinfection by-products may be a trigger for you. Change pools or talk with the management about proper pool maintenance to reduce respiratory irritants.
  • Swimming pool workers (such as lifeguards) and elite swimmers have higher incidences of respiratory symptoms including asthma due to their high level of exposure. I personally would not encourage (but also would not forbid) my kid to work as a lifeguard or join the swim team, especially if the venue were an indoor pool. But I also recognize that for some families the pros of competitive swimming or a job as a lifeguard may outweigh the cons.

In short: Choose a properly maintained outdoor pool. Get rid of chlorine on and in your body as soon as possible after swimming. And enjoy your pool activities in moderation. 

Where does your family swim? How do you reduce risks of chlorinated pools?

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