HEPA - High Efficiency Particulate Air

High Efficiency Particulate Air Filters, or simply HEPA filters are highly efficient filters for air purifying, that boast the removal of up to 99.97% of particles in the air that are 0.3 micrometers or bigger. The 0.3 size has been one of the hardest to purify over the years, and is the size of many airborne threats, making HEPA filtered machines very successful in cleaning the atmosphere.

HEPA filters are created through a strip of fibers that vary in diameter, size and density so they can effectively block all types of particle. It is not however a simple sieve process, instead particles are either blocked via interception (where particles going in one direction of airflow are cut off by the fibers and stick to them in a diagonal motion), by impaction (where larger particles are simply blocked right away), or by diffusion (where the addition of gas helps slow down the particle’s journey, increasing chances of interception).

One of the more common uses of HEPA filters are not in traditional air purifiers, but in vacuum cleaners to trap in the dust and particles. The air, dust and particles are sucked in by the cleaner and then a HEPA filter is used to only let the pure air back out. Beyond air purifiers, which haven’t become commonly used in households until recently, vacuum cleaners work great for those with asthma, who need more protection from dust mites and smaller particles than the average person.

HEPA filters are also commonly used in the medical profession in special HEPA purifying units. Some units have reached a 99.995% efficiency rate, making them indispensable for protection against airborne threats and diseases.