Indoor pools can provide a wonderful venue for exercise during cold winter months. Swimming is a full-body, aerobic workout that is easy on the joints while building muscle strength and tone (National Swimming Pool Foundation website). Yet, poor indoor air quality may be a deterrent to winter swimming. What causes poor indoor pool air quality, and what can be done to improve it?
The Culprit: Chloramines
Chloramines are the chemical compounds that produce that stinging, irritating odor around some pools. Many people attribute the distinctive odor to chlorine, but chlorine is only half of the story. What we smell are compounds known as chloramines. Chloramines form in pool water when two ingredients combine chemically: chlorine + organic nitrogen (amines) in natural waste products from swimmers. Chlorine is added to pools to destroy the waterborne germs that could make swimmers sick. Natural waste products from swimmers (here is where we must get graphic, sorry), include body oils, perspiration, urine and fecal matter.
Clearing the Air at the Indoor Pool
✓ Shower before swimming
✓ Don’t pee in the pool
✓ Monitor and maintain appropriate pH and free chlorine levels
✓ Vacuum and brush the pool
✓ Shock treat the pool as needed
✓ Vent the indoor air to the outside
Reducing Chloramines: The Swimmer’s Role
Knowing how chloramines are generated in swimming pools helps us understand how to reduce them. Starting with the “natural wastes from swimmers” factor, swimmers should be encouraged to shower before swimming, paying special attention to the perianal area, where, as one researcher notes, on average, 0.14 g of feces is present (children are likely to have more). Using this statistic, a community pool holding 50 swimmers contains, on average, approximately 7 grams of feces. Feces contain pathogens on the order of one million per gram, so now our theoretical pool contains 7,000,000 pathogens. That’s 7,000,000 reasons why we want chlorine to be available to disinfect the water, and not “tied up” as chloramines.
In addition to showering before swimming, swimmers also should be encouraged not to “pee in the pool.” Olympic swimmers’ comments to the contrary, this is not an insignificant effect. The January, 2013 issue of Pool & Spa News quoted Maryland-based aquatic consultant, Frank Goldstein, as saying urine “may not have bacterial properties, but that doesn’t mean it’s not affecting the water chemistry.” The ammonia in urine and sweat, for example, deplete chlorine by combining with it. Instead of chlorine being available for disinfecting the water, it helps form smelly irritants. Chloramines are the reason for swimmers’ red eyes and itchy skin.
Reducing Chloramines: The Pool Operator’s Role
Every pool operator, whether formally trained for the role or not, should regularly check water quality (monitor pH and free chlorine levels to make sure they are within acceptable bounds), clean the pool and “shock it” as needed. Chloramines can be reduced in pools by “shocking” the pool when the pool is not in use. This involves temporarily raising the chlorine level to rid the pool of chloramines by chemical oxidation. Some pool managers shock pool water on a weekly basis to control chloramines. Another tactic is to vacuum and brush the pool daily to remove much of the dirt chlorine reacts with that has not been trapped in filters.
Because some chloramine formation in swimming pools is inevitable, and chloramines, being volatile, diffuse into the air, it makes sense to vent the air around the pool to the outdoors, replacing it with fresh air. Good ventilation is also important to reduce humidity levels in the pool environment. Although rising energy costs have made this measure more expensive in recent years, it is no less important in maintaining good indoor pool air quality.
Emerging from the locker room onto the pool deck and into a moist cloud of irritant-laden air is hardly conducive to a satisfying winter workout. Clearing out the chloramines, which is a team effort between the pool operator and the swimmer, can help.
Chris Wiant, M.P.H., Ph.D., is president and CEO of the Caring for Colorado Foundation. He is also chair of the Water Quality & Health Council.