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Summer weather often means more swimming pool time, although many indoor pools, spas and hot tubs are used year round.   A number of potentially hazardous chemicals are added to provide continuous disinfection within the water of swimming pools, spas, and hot tubs at all times and to maintain “balance” in terms of pH, alkalinity and hardness.  Consumers who maintain their own pools purchase, transport, store, use and dispose of these chemicals.

Pool chemicals are safe when handled properly, but can cause injury when mishandled. There are 10.4 million residential and 309,000 public swimming pools in the United States (1).    In a study conducted by the U.S. government that looked at 400 chemical release incidents, human error was the most frequent contributing factor (71.9%), followed by equipment failure (22.8%) (2).   With proper education, many of the human errors can be prevented.

What harm can pool chemicals cause if used inappropriately?

Health problems most frequently reported were respiratory irritation (47.9%) and eye irritation (19.4%),followed by gastrointestinal problems, skin irritation, shortness of breath, headache, burns, and dizziness/CNS disturbances. Explosions and fires are also possible with highly reactive disinfectants and oxidizers.  Consult labels and Safety Data Sheets for potential hazards caused by misuse or excessive exposure to the specific chemicals you are using.

How to avoid harming yourself and others when using pool chemicals

Be knowledgeable about the chemicals you are using to treat your pool and take proper precautions. Avoid using greater quantities than specified on the label—do not assume “more is better.” Using these chemicals other than as directed is never a good idea.

Read labels before you use pool chemicals. Follow carefully all directions for use, storage and disposal. Wearing shoes, gloves, and safety glasses and any other appropriate personal protection is also recommended when pouring liquids. The video links shown in the further information section below offer much more important detail about this topic.

Should swimmers, lifeguards or others who work around pools be concerned about chronic exposure to swimming pool water?

A key point to remember always is that “the dose makes the poison.”  Pool chemicals properly used according to manufacturer’s specifications are intended to achieve the desired effects yet not cause harm to swimmers. Concerns associated with misuse focus on acute effects—that is, short term exposures to relatively high doses.  If pool chemicals are used correctly the benefits of swimming outweigh any potential harm. Several authoritative sources even report that for asthmatics, swimming is actually one of the best exercises! (3)

Some lifeguards with pre-existing respiratory conditions, for example asthma, have occasionally reported a worsening of symptoms after working at indoor chlorinated swimming pools. However, always keep in mind that risks can be reduced or eliminated entirely by reducing exposure. Adequate ventilation at indoor pools is very important, as is enforcement of proper workplace practices related to handling and use of pool chemicals (4).

The policy of showering before entering the pool to help maintain cleanliness of the pool water applies to everyone and can reduce the amount of disinfection needed and formation of disinfection byproducts. The bottom line is that although pool chemicals necessarily have toxic properties (or else they would not kill unwanted germs and other microorganisms), if employers, workers and swimmers all follow recommended procedures, the benefits of their use far outweigh any potential risks.
(1)  U.S. Centers for Disease Control and Prevention,
(2)  Anderson AR, Welles WL, Drew J, Orr MF (2014) The distribution and public health consequences of releases of chemicals intended for pool use in 17 states, 2001-2009. J Environ Health. 76(9) 10-15.
(3)  See, for example: Font-Ribera L, et al.  Swimming pool attendance, asthma, allergies, and lung function in the Avon Longitudinal Study of Parents and Children cohort.  Am J Respir Crit Care Med. (2011 Mar 1);183(5):582-8. doi: 10.1164/rccm.201005-0761OC.
(4)  California Department of Public Health, Occupational Health Branch, Pool Chemicals and Work-Related Asthma – Information for Employers,


Resources for further information:

Pool Chemical Safety:    This video, intended for homeowners and commercial pool managers, outlines the safe use of pool chemicals.   Produced by the American Chemistry Council and the Chlorine Institute, the video includes health and safety messages from the U.S. Centers for Disease Control and Prevention (CDC).

You can also view each section of the pool chemical safety video through the following clips:

Intro to Pool Chemical Safety (2:08)

Properties and Safe Storage of Pool Chemicals (5:12)

Pool Chemical Handling (2:07)

Pool Chemical Accident Prevention and Response (2:03)

Pool Chemical Safety Recap (2:11)


Related topics:   Basics of Dose and Exposure; Hazard vs Risk

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