What Is a HEPA Filter Made of?

Materials

• HEPA filter material resembles paper, but actually consists of a network of fiberglass fibers, according to HEPA Filter Pro. Incoming particles stick to these fibers, embed themselves in them, or bounce off of them until other fibers finally stop their progress.

Weave

• Instead of using a standard grid or screen configuration in its weave, a HEPA filter employs a thick, seemingly random maze of closely intertwined fibrous strands, according to Air Purifiers. This weave increases the chance of a tiny particle getting caught in the fibers and sticking to them, instead of traveling through in a straight line.

Layering

• A HEPA filter that tried to prevent nearly all particles from penetrating a single sheet of material would get clogged too frequently, requiring constant changing. For this reason, HEPA filters instead use multiple layers of sheets, to catch the incoming particles in stages. A single HEPA filter may contain up to 40 square feet of material.