Air Purifiers: What is a HEPA filter?
High Efficiency Particulate Air (HEPA), is a term that describes filters that are able to trap 99.97 percent of particles that are 0.3 microns. In other words, for every 10,000 particles that are 0.3 microns in diameter, only three of them pass through. HEPA filters are commonly used in hospital settings and laboratories to filter air that contains bacteria, viruses, dust and other contaminants to ensure clean and sterile environments for patients or research.
The diameter specification of 0.3 microns responds to the worst case; the most penetrating particle size (MPPS). Particles that are larger or smaller are trapped with even higher efficiency. Using the worst case particle size results in the worst case efficiency rating (i.e. 99.97% or better for all particle sizes)
Air purifiers require periodic cleaning and filter replacement to function properly. It is important to follow manufacturer's recommendations on maintenance and replacement to ensure high air quality.