When it comes to improving indoor air quality, few technologies are as trusted and widely used as HEPA filters. Whether in vacuum cleaners, air purifiers, or HVAC systems, HEPA filters are relied upon to remove tiny airborne particles that may trigger allergies, respiratory issues, or the spread of pathogens. But have you ever wondered—what exactly are HEPA filters made of?Understanding the materials behind HEPA filters helps explain their high performance and effectiveness. In this article, we’ll explore the core components, structure, and reasons why HEPA filters are so efficient at trapping particles as small as 0.3 microns.What Does “HEPA” Mean?Before diving into the materials, let’s define what HEPA stands for. HEPA means High-Efficiency Particulate Air. A filter must meet strict standards to be classified as HEPA, particularly in its ability to capture at least 99.97% of particles measuring 0.3 microns in diameter—the most penetrating particle size (MPPS).The Core Material of HEPA FiltersThe main material used in HEPA filters is a dense mat of randomly arranged fibers, typically composed of:Glass microfiber (borosilicate fibers)Synthetic polymer fibers (like polypropylene or polyester)These fibers are extremely fine—often less than 1 micron in diameter—and are layered into a thick, pleated sheet to increase the surface area. The result is a material that allows air to pass through while capturing solid particles through mechanisms such as interception, impaction