Deteriorating floor tiles are to blame for two school closures Monday in the St. Louis Park district.
Students were sent home from both the junior and senior high school buildings after officials discovered tiles that had eroded through contact with salt and other particles on people's shoes.
District spokeswoman Sara Thompson says officials worried the erosion might expose students to asbestos.
"As long as they're in good shape, there's no hazard," Thompson said. "But as soon as the tiles start to crumble or are stripped in any way, there is a concern, based on the age of the tiles, the makeup of the tiles, and the glue used to adhere the tiles to the floor."
The tiles were discovered in a nurse's office and a classroom. The district is evaluating how to remove the hazard.
The senior high will remain closed tomorrow - a decision has not been made yet on the junior high.
Thompson said it's unclear how old the tiles in question are. Both buildings were built in the late 1950's. The junior and senior high schools are located about 2.5 miles from each other.