The chlorine in pools can cause a lot of trouble, according to an EPA journal called Occupational and Environmental Medicine.

According to the article, chlorine can mix with skin cells and skin care products -- have you read their labels lately? -- to form dangerous volatile chemicals.

While swimming, you can breathe the chemicals in, or swallow them. This can cause health problems in folks with chronic heart or lung disease, and also in healthy people, especially pregnant women.

For example, British researchers found that the average pool contained chloroform, an irritant, up to 35 times the amount found in tap water. Chloroform can irritate the nose, sinuses, lungs and skin.

Pools also contain germs, which can cause skin infection, and they help grow mold, which can also cause health problems in the nose, sinuses and lungs.

What to do?

Shower with soap and water before and after you take a swim. Or, find a clean lake.