21 Asbestos Safety Manual Environmental Health and Safety Enclosure Enclosure involves a permanent airtight, impermeable barrier between the ACM and the building environment that prevents asbestos fibers from escaping into the air. This measure has limited applicability and is typically used only for small amounts of material on isolated columns or beams. Removal Removal is the most definitive response action to an asbestos problem. Once ACM is removed from the building, the potential for a hazardous fiber release is eliminated, as is the need for surveillance. Removal becomes necessary when in place management is no longer feasible or effective in protecting building occupants, or when renovation or demolition activities will disturb ACM.