HEPA filters are highly effective air cleaners

HEPA filters are designed for commercial applications

A HEPA filter has been traditionally defined as an extended-surface dry-type filter having a minimum particle removal efficiency of 99.97% for all particles of 0.3 micron diameter with higher efficiency for both larger and smaller particles. This rating is determined using a test challenge smoke that consists of particles of 0.3 micron average diameter. To qualify as a "true" HEPA, the filter must allow no more than 3 particles out of 10,000 to penetrate the filtration media.

The filtering media of a HEPA filter is made of submicronic glass fibers in a thickness and texture very similar to blotter paper. More recently, filters made in the same physical style using less efficient filter paper are being referred to as HEPA filters or "HEPA-type" filters. Their actual efficiency may be 55% or less at 0.3 microns. While still very good filters when compared to conventional panel type and even extended-media pocket filters, these versions of the original HEPA filter have higher airflow, lower efficiency, and lower cost than their original version. The true HEPA has very high pressure drop performance and both versions require prefiltration for maximum life cycle.

HEPA filters are proven effective in recent studies

1990 review of indoor air pollutants and environmental controls published by the American Thoracic Society (1990) concludes that: "High-efficiency particulate filters (HEPA) are highly efficient in removing particles of a wide range of size. A room-size unit will control particles in that room, and a central unit will remove particles from the air of the building when the ventilation system is operating.

HEPA is generally not a residential filter application

HEPA filters are generally not applied to residential HVAC systems due to their size and horsepower requirements. A disadvantage of HEPA filters is that the need for a powerful fan leads to increased energy costs compared to less efficient filtration systems, and replacement filters are generally quite expensive (retail prices range from $50 to $100, depending on size). The major advantages of the original HEPA filters, however, include high efficiency, which actually increases with use, and a long maintenance-free life cycle of up to five years when used with a prefilter

Editors' Top Picks

Best home air filters

5 star product As it is not clearly evident that air duct cleaning has a lasting effect on improving indoor air quality, we suggest that you consider an easy and economical solution that combines air ionization technology, ozone air cleaning, and UV germicidal protection. Product details.

New! Organic air purifiers and how you can utilize natural air filters in your home
Before you spend hundreds or thousands of dollars on the latest technological breakthrough in indoor air purification take a moment to read about a cheap and easy low-tech solution. Read article...

Air purifiers and air filters article library.
Read all about solutions and issues related to indoor air pollution with strategies and ideas to clean up your own home's indoor air quality. Read articles...