Transcript for Pool Safety Alert: Improperly Mixed Chemicals
More and more Americans looking to start swimming this weekend, but there could be a danger in the swimming water. We have a hazmat team on the way. Reporter: Here's exactly what health authorities are trying to prevent. More than 70 children and their families at a local pool in Indiana, struggling to breathe after someone misused the chemicals that maintain the pool. My nephew has thrown up seven times. Like, 20 times. There's something toxic in the pool or something. Reporter: Many had to be hospitalized. Their eyes were burning. They had to give children oxygen. New Numbers from the CDC say there were nearly 5,000 emergency visits caused by pool chemicals in 2012. Almost half were children. Nearly half the injuries were poisonings, swallowing chemicals, or breathing vapors. And most of those happened on a weekend. Nearly 73% in the summer months after the memorial day holiday. Those are just the people that need treatment. That's only the tip of the iceberg. Reporter: Chlorine, hydrochloric acid. Pool chemical suppliers warn families to follow the instructions, apply them close to the water's surface, and store what's left far away from petroleum products. Gasoline, brake fluid, transmission fluid, it can't touch or interact with those products. It will explode. Reporter: They say don't wait till the moment the kids are ready to jump in. Add chemicals the day before and make sure the water is circulating. And teach kids to always avoid drinking pool water. Steve osunsami, ABC news, Atlanta.
This transcript has been automatically generated and may not be 100% accurate.