Pool chemicals help protect swimmers from germs in the water, but the disinfectants themselves can be hazardous if used improperly, warns a new report from the Centers for Disease Control and Prevention.

In 2012, nearly 5,000 people in the United States visited an emergency department for injuries from pool chemicals, the report says.

The researchers found that 46 percent of those injuries occurred among children and teens, and more than a third happened at home. Nearly three-quarters of injuries took place between Memorial Day and Labor Day, and about 40 percent happened on weekends. [7 Common Summer Health Concerns]

The most common type of injury was poisoning, usually from inhaling pool chemical fumes. People were typically injured when they opened containers storing pool chemicals without wearing protective equipment (such as goggles), or when they entered the water right after chemicals had been added.

"Chemicals are added to the water in pools to stop germs from spreading. But they need to be handled and stored safely to avoid serious injuries,” Michele Hlavsa, chief of CDC's Healthy Swimming Program, said in a statement.

To prevent pool chemical injuries this summer season, the CDC recommends that people read and follow directions on product labels, wear safety equipment such as goggles and masks when handling pool chemicals, keep young children away from those individuals handling pool chemicals, and lock up pool chemicals to protect people and animals. Individuals should never mix different pool chemicals with each other, and should never add water to pool chemicals, the CDC said.

Because these chemicals typically take a few minutes to kill germs, swimmers can take additional steps to keep germs out of the water, including not swimming when they have diarrhea, and taking children on frequent bathroom breaks, the CDC said.

Swimmers can also protect themselves from germs by not swallowing pool water.

The report is based on information from about 100 hospital emergency departments, which the researchers used to estimate the number of pool injuries nationally. Between 2003 and 2012, there were typically about 4,000 emergency visits per year related to pool chemicals, and in 2012 there were about 4,900, the researchers estimated.

The report is published this week in the CDC's Morbidity and Mortality Weekly Report.

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