Kids should play in sand, not breathe it in.

Wisconsin’s New Auburn school district is upgrading air filters to prevent sand fragments from floating in from nearby frac-sand mines and getting into children’s lungs.

Much of the sand in the state is perfectly suited to be mixed with water and chemicals and used in fracking operations, where it holds open fractures in shale and allows gas and oil to escape. That’s fueling a $1-billion-a-year sand-mining boom, which is bringing notable environmental and health risks to the state.

The Eau Claire Leader-Telegram reports:

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Four sand mines operate within a few miles of the school, with the closest less than a half-mile away.

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As the number of sand mines near New Auburn and in Chippewa County has increased in the past couple of years, school district officials decided to see whether sand was getting into the building’s air system.

“We took dust scrapings off the filter and sent it to a lab in Madison,” [Superintendent Brian] Henning said. “There was a small percentage of silica on those filters.”

A recent test revealed a small amount of sand in the filters. While district officials hoped no sand would be in the filters, they’re grateful the filters are doing their job, Henning said.

Many municipalities in the state regulate sand-mining operations, and some ban them. But a bill in the Wisconsin legislature, Senate Bill 349 [PDF], could prevent local governments from imposing their own controls on the industry. That could lead to the expansion of existing mines and the opening of new ones, regardless of objections from locals.

“Think of the areas that are susceptible to frac-sand mining right now,” Dane County Executive Joe Parisi recently told the Wisconsin State Journal. “[The towns of] Berry and Cross Plains, a beautiful part of our county. And there could be virtually unregulated mining in those areas and we could not do anything about it.”