When it comes to air purification, it is important to understand the difference between true HEPA and HEPA-type filters. A true HEPA filtration device or filter is the only type of HEPA filter that truly conforms to the DOE standard for HEPA filtration, has the highest efficiency, and reaches the 99.97% threshold. Absolute HEPA is a term that is often used interchangeably with true HEPA, but the only difference between the two is that absolute HEPA filters claim to remove more than 99.97% (but less than 100%) of particles that are 0.3 microns in size. The acronym HEPA stands for high-efficiency particulate air filter. To be considered a true or genuine HEPA filter, it must meet certain requirements, such as the ability to trap 99.97 percent of particles that are 0.3 microns in size.
HEPA filters typically have a pleated design with some mesh elements to trap particles. In addition, it may also be useful to review what CFM is in an air purifier. Efficiency describes the percentage of particles that a device removes from the air passing through it. True HEPA filters are tested for efficiency by feeding them with a 0.3 micron particle cloud. The density of the particles is measured before and after passing through the filter, and the efficiency is calculated from these values. Efficiency, on the other hand, refers to how well a device cleans the air in a room.
A filter that is too small or inadequate can be ineffective in a situation, even if it has a high efficiency, whether it is true HEPA or HEPA-like.