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(HealthDay News) -- Indoor swimming is especially popular during the winter, and no one disputes its benefits for keeping fit.

However, a recent study by the U.S. government's National Institute of Environmental Health Sciences (NIEHS) showed that continued exposure to disinfection byproducts around indoor pools may damage protective lung cells and even lead to asthma.

Here are a couple of suggestions the NIEHS says can reduce your risk:

• If you are a regular indoor pool swimmer, consult your doctor to determine whether you may have a problem.
• Reduce your pool time by an hour a week.