A new study published in the journal Pediatrics, found that children who spend a lot of time at indoor swimming pools during their early years are more prone to developing asthma and other breathing problems as they grow older, compared to others who do not frequent indoor pools.
They believe that harmful gases trapped indoors from the chlorinated pools are to blame for the airway damage. The main culprit: trichloramine, or nitrogen trichloride, is created when chlorine reacts with ammonia, which can be found in the sweat and urine from swimmers.
Swimming is both a great form of exercise and a vital life-saving skill for little ones. However, I don't recommend swimming in swimming pools, whether indoors or out, since your body absorbs more chlorine by swimming in a chlorinated pool than you would by drinking tap water for one week.
If you don't have access to a lake, ocean or other natural body of water, using peroxide (not bromine) is also an alternative for chlorine in your private pool. A product called Baquacil is available at most pool stores that can do the job safely. If all else fails--try to stick with outdoor pools, as at least the fumes are whisked away by the open air.
Pediatrics 2007 Jun;119(6):1095-103