1. Glass Microfibers: High-Efficiency Particulate Air (HEPA) filters are typically made of borosilicate glass microfibers arranged in a random, web-like formation. These glass fibers are composed of oxides of boron, oxygen, and silicon. The diameter of each fiber ranges from 0.5 to 2 micrometers. The dense network of these tiny fibers acts as a highly efficient barrier, capturing most particulate pollutants found in air.
2. Polymer Media: Some HEPA filters may utilize synthetic polymer fibers instead of glass. These polymer materials undergo a bonding process called "melt-blowing" at high temperatures to form fibrous sheets. Polypropylene is a commonly used polymer in HEPA filters due to its ability to capture particles effectively and efficiently.
3. Cellulose Fibers: In certain cases, HEPA filters are constructed using cellulose fibers derived from natural sources like wood pulp or cotton. While less common compared to glass microfibers or polymer, cellulose filters can still exhibit commendable particle filtration capabilities.
