Feeling breathless in the pool? It may not be just because your suit, like ours, has somehow gotten a little tight. For, not only does chlorine corrode (and shrink?) swimsuits, bring on the itch fits and shrivel hair to straw, but it can bode ill for lungs: Chlorinated pools have been implicated in the rise of childhood asthma. Regular swimming in an indoor pool was found to be "among the most consistent predictors of asthma...ranking immediately after atopy [allergies] and family history," Belgian university researchers reported in Environmental Health Perspectives (EHP).

"All these effects were dose related and most strongly linked to pool attendance before 6-7 years," the researchers said. So if you've got young children, it's worth checking out levels of chlorination where they swim. Ever wonder if those lifeguards at the Y are a little overzealous about dumping in the chemicals? In a worst case scenario, when accidentally exposed to a large amount of chlorine gas at a swimming pool, several children suffered respiratory impairment, according to a study published in the American Journal of Respiratory and Critical Care Medicine. But that was an accident, so there's no reason to panic.

Remember, chlorine kills pathogens and reduces risk of disease in drinking water, as well as pools. It's the dose that makes the poison, and the key is to lower the dose while preventing unhealthy levels of bacteria. Here are some chlorine reduction tips:

* Swim in chlorinated pools every other day, at the most, rather than daily. Chlorine and its toxic byproducts do not collect in the body, according to The Green Guide, which advises that taking some time off in between sessions will allow your body to detox a bit and your lungs to recover.

* Choose outdoor pools, which allow toxic vapors to disperse, rather than indoor pools, which trap them. In our experience, some of the cleaning products used on indoor pool decks can also add to the asthmatic miasma.

* Ask your pool management for assurances that chlorine levels are regularly checked and do not exceed safety thresholds, that chlorine is added with adequate time before swimmers enter the water and that good ventilation is maintained at all times. Request that  nontoxic cleaning products be used on pool decks, and applied when pool is closed.

* If you're a pool owner, explore ways to safely reduce chlorine. Ideally, we would all have outdoor natural swimming pools that replicate wetlands, filtering out toxins with water plants. Or there's a Technopure system that pumps pool water through metal-coated plates that supposedly oxidize and burn off organic waste, costing about $5,500, according to the New York Times, which notes that going entirely chlorine-free with either metals or aquatic plants can cost up to $10,000-$20,000 extra.

Least extreme is to minimize chlorine with (1) an ozone generator, available with energy-efficient pumps, that oxidizes bacteria and kills microorganisms and reduces need for chlorine by 60 to 90 percent, according to the company, DEL; costs about $900. Or (2) a system that kills bacteria with trace amounts of silver and algae with copper, reducing chlorine needs by 50-80 percent, according to the maker, Zodiac, $180 for a season's cartridge. 

* Before going for it, ask if any alternative pool service has been third-party certified by the National Sanitation Foundation (NSF) as being truly effective against pathogens.

* Keep bacteria out of the pool by making sure that swimmers wash with soap before diving in.

* It's summer, so enjoy totally non-chlorine alternatives, like a pond or clean beach.

This article originally appeared in Plenty in July 2008. The story was added to MNN.com.

Copyright Environ Press 2008