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What’s In the Pool? Chlorine vs. Chloramine

A refreshing dip in the pool can provide much needed relief from the summer heat. Various chemicals are added to pools to prevent unwanted bacterial growth. Exposure to these chemicals and other unwanted substances can happen during routine maintenance or while swimming in the pool. Symptoms are varied depending on the extent of the exposure. Is chlorine always the chemical to blame for these symptoms?


Chlorine ExposureKeeping a swimming pool in tip-top condition requires periodic handling of potentially toxic chemicals, most notably chlorine products. The chlorine source is usually liquefied chlorine for very large pools, and chlorine salts for smaller and residential pools. When inhaled accidentally, chlorine can cause immediate coughing, choking, and a feeling of suffocation. Individuals may also complain of nausea, burning chest pain, nose and throat irritation, and skin and eye irritation. Sometimes this can progress to more severe symptoms that require treatment in a hospital.

The first step to treatment at home is leaving the source of chlorine and moving into fresh air. When able, an exposed person will immediately escape the exposure site due to the intolerable nature of the toxin. It is likely the person may also have eye and skin contact with the chemicals. Immediate irrigation (rinsing well) with copious amounts of tap water for 5 minutes is essential. For persistent pain or irritation after a thorough irrigation, an eye or dermal exam may be needed due to the corrosive nature of chlorine to the skin, eyes, and mucous membranes.

Sometimes due to persistent coughing, dyspnea, and chest pain, the exposed individuals will present in the Emergency Department. These patients may require oxygen, breathing treatments, and other medications to resolve their symptoms.


  • Store pool chemicals in a COOL, DRY, WELL VENTILATED area, away from other household products and garden chemicals.
  • Keep children and pets out of the area when using chemicals.
  • Never walk away from any product that is out, open, and in use.
  • Use recommended protective equipment such as gloves or masks when handling hazardous products.
  • Never mix chemicals of any kind together. An unexpected and uncontrollable reaction may occur.
  • Store products in the original container, up and out of reach, in a locked cabinet or location if possible.


After a pool has been treated with chlorine, it is now ready to swim! However refreshing the swim was, your eyes can sting and appear red afterwards. Many people assume the chlorine is the culprit for this effect, but we would like to investigate this phenomenon a little further.

Minor conjunctivitis (red eyes) after swimming can be accompanied by the appearance of haloes around lights, with little or no blurring of vision. Each of these reactions can be explained by the complicated chemistry that takes place in the pool water itself. You may be surprised that it is not directly caused by the chlorine!

The antiseptic agent of chlorine is called hypochlorous acid. Some of this acid is “consumed” (taken up) while destroying the microbes in the water and it is also broken down by sunlight. Any hypochlorous acid that remains is free to react with nitrogen containing compounds.

Pool Red EyesNitrogen enters the swimming pool water from several sources. Since most of the Earth’s atmosphere is nitrogen, there is a small reaction between the hypochlorous acid and the free nitrogen gas in the air. However, most of the nitrogen is actually introduced from the swimmers themselves through urine, perspiration, feces, spit, and bacteria on the skin. When the nitrogen compounds react with the hypochlorous acid, chloramines are formed (“chlor” is short for chlorine, and “amines” are compounds that contain nitrogen). The chloramines have a distinct pungent odor which is often falsely attributed to chlorine and they are particularly irritating to the eye. Although the effects of the chloramine in the eyes are irritating, they are not serious after exposure to pool water. Virtually all cases of eye irritation will return to normal within 24 hours without treatment.

So, the next time someone complains that the chlorine at the pool is irritating their eyes, you can dazzle them with your chemical knowledge and assure them that it is not the chlorine.

The Missouri Poison Center wishes you a fun and safe summer. If you have questions or concerns about chlorine please contact the Missouri Poison Center at 1-800-222-1222.

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