Worried that floor tiles worn down by tracked-in salt and sand could be releasing dangerous asbestos, officials closed two St. Louis Park schools Monday.

The city's junior and senior high schools will remain closed Tuesday as state and school officials work to assess the hazard and determine if other schools face similar problems.

Asbestos floor tile was commonly installed in hundreds of 1960s-era schools across the metro area, but it remains unclear how many could still have the asbestos tile or how much risk St. Louis Park students faced, said one expert at the Minnesota Department of Health.

"For any parent with kids there, they should not be concerned," said Dan Locher, supervisor of the asbestos and lead unit at the agency. "Most likely they weren't getting exposed to asbestos."

But the company testing the two St. Louis Park schools for asbestos Monday and Tuesday will be "taking a closer eye" on the 60 other Minnesota schools it works with.

"We're definitely going to be informing our clients -- other school districts -- about what we found, and we'll definitely be taking steps to monitor it," said Diedra Hudgens, senior project manager at Brooklyn Park-based Institute for Environmental Assessment, or IEA. "Every district has an elementary school or something this vintage."

Scott Croonquist, executive director of the Association of Metropolitan School Districts, said Monday night that districts throughout the metro area and the state have been dealing with asbestos abatement and removal. He did not have information, he said, suggesting that a "bunch of buildings," for example, may need asbestos removal, or pose a danger.

But, generally, Croonquist said, funding has lagged statewide for school renovation and deferred maintenance. "It's an area we're definitely behind in in the state," he said.

Hudgens said most schools are able to isolate asbestos issues, but shutting down schools like St. Louis Park junior and high schools did on Monday and Tuesday is rare. "This district's just being very proactive," she said.

State education officials also said the district was "right to err on the side of caution.''

In a statement Monday night, the department said, "If asbestos is found at the schools, we will do everything we can ... to ensure the schools are safe."

Complaints about dust

St. Louis Park school staffers complained late last week about dust outside a school nurse's office, prompting IEA tests on Saturday. A protective wax layer had been worn down by salt and sand tracked in from roads and sidewalks, dulling the floor.

As a precautionary measure on Monday, school was dismissed for additional testing at both the high school and the nearby junior high -- which has similar flooring.

Tile was removed from the high school and Monday the school was tested by IEA crews in full protective gear.

The 1,000 sixth- through 12th-grade students were bused home, district spokeswoman Sara Thompson said.

Floors are waxed two to three times a year, but Thompson said she didn't know when the floors were last covered, or how much it costs the district.

Asbestos tile was widely used in the 1960s for its durability, dubbed "a miracle mineral," Locher said. But by the early 1970s, it was discovered that inhalation of asbestos fibers can cause lung cancer and other deadly diseases.

The tile found in schools, though, has low levels of the asbestos -- no more than 10 percent -- Locher said. And as long as it's contained, such as with a wax layer like at St. Louis Park High School, it poses no risk.

Concerned parents should contact the district, he said. School districts are required by federal guidelines to test asbestos tile every six months.

This is the first time the school district has shut down schools due to asbestos, she said. "This was a unique situation due to all of the snow and salt on the roads."

Senior Jessica Bigirindavyi said students cheered at the news of school's cancellation.

"It's a good Valentine's Day gift, I guess," she said.

Staff writers Anthony Lonetree and Paul Walsh contributed to this report. Kelly Smith • 612-673-4141