I have seen the janitor machine-cleaning the floor tile in our school. Should I be worried that these machines will degrade the tiles and create a hazard?

Machine-cleaning of floor tile can be part of a good maintenance program for asbestos-containing floor tiles, as long as the machine is operated properly and the tiles are not in poor condition. EPA has issued special guidance on the proper maintenance of asbestos-containing floor tiles, and the guidance is available from the TSCA Hotline at (202) 554-1404. Undamaged, well maintained floor tiles present little risk to students, teachers, and school staff.