HEPA means High Efficiency Particulate Air Filter or High Efficiency Particulate Absorbing Filter.

HEPA filters can be highly effective, but they also have some serious drawbacks. They are not the best choice for everyone.

In theory, HEPA filters can retain 99.97% of dust, pollen, bacteria and all particles with a size of 0.3 microns or more.

For purposes of comparison, the smallpox virus has a diameter of only 0.22 microns, so to block it we need a filter with even finer cells. On the other hand, the tuberculosis bacillus has a diameter of 1 to 3 microns, so the HEPA filter can easily block it.

High density filters like HEPA filters are expensive, clog easily, and their resistance to airflow is higher because they retain more dust. If you don't have particular health problems, we recommend the Air-T-Rex or the MervPlus pleated filters instead.