What is a HEPA filter?

HEPA stands for High Efficiency Particulate Air.

Historically HEPA filters were designed by the Atomic Energy Commission in the US to trap radioactive dust particles.

It is a filter that is able to remove 99.97 percent of particles in the air - particles as tiny as 0.3 microns. To be called a HEPA filter the filter must meet the minimum standard of filtering out all particles > 0.3 microns. Some manufacturers HEPA filters exceed this minimum standard.