PHILADELPHIA - The union representing public school teachers in Philadelphia is suing the district over its handling of asbestos contamination in schools, the union said Monday.

The Philadelphia Federation of Teachers suit comes after the city school district was forced to close a north Philadelphia elementary school for a second time Friday after tests demanded by teachers and union leaders showed elevated levels of asbestos, a known carcinogen, in the air.

The Philadelphia Inquirer reports that district leaders had assured teachers a day earlier that McClure Elementary School was safe to enter.

“Time and again, the School District has claimed that their actions are out of an abundance of caution,“ union president Jerry Jordan said in a statement. “What we’ve seen time and again is the District’s willingness to throw caution to the wind and as a result put children and educators at risk.”

The school district said in a statement Monday that it would “thoroughly review” the legal filings while remaining focused on improve environmental conditions in schools.

“All of our students and staff members deserve that we stay 100 per cent focused on our efforts to improve environmental conditions in schools. We will do just that,“ the district said.

The district said earlier that it had been working with the union since November on a document outlining processes and protocols but had not heard back on suggested edits and final approval.

The statement Monday said officials hoped to focus on finalizing the document and “genuinely working together — without distractions — to address environmental issues effectively and with the urgency our students and staff deserve.“