Which encapsulation type forms a protective membrane over ACM?

• A. Bridging
• B. Penetrating
• C. Coating
• D. Layered

Answer: (A)

When dealing with asbestos-containing materials, encapsulation methods aim to prevent fiber release by creating a barrier. Bridging encapsulation is the one that forms a protective membrane over the surface of ACM. It applies a coating that dries into a continuous film across the material, spanning cracks and surface imperfections to seal fibers at the exterior. This creates a physical skin or membrane that blocks fibers from becoming airborne, which is especially important on damaged or friable ACM.

Penetrating encapsulation works by penetrating into the material to bind fibers from within, but it doesn’t create that surface membrane. A coating encapsulation also forms a surface film, but it doesn’t specifically address bridging gaps or cracks like bridging encapsulation does. For forming a protective membrane over ACM, bridging is the best-fit description.