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For other uses, see Hepa (disambiguation).
HEPA filter with functional description

High-efficiency particulate arrestance (HEPA),[1][2] also sometimes called high-efficiency particulate arresting or high-efficiency particulate air, is a type of air filter. Filters meeting the HEPA standard have many applications, including use in medical facilities, automobiles, aircraft and homes. The filter must satisfy certain standards of efficiency such as those set by the United States Department of Energy (DOE). To qualify as HEPA by US government standards, an air filter must remove (from the air that passes through) 99.97% of particles that have a size of 0.3 µm.[3]





Lastly, it is important to note that HEPA filters are designed to arrest very fine particles effectively, but they do not filter out gasses and odor molecules. Circumstances requiring filtration of volatile organic compounds, chemical vapors, cigarette, pet, and/or flatulence odors call for the use of an activated carbon (charcoal) or other type of filter instead of or in addition to a HEPA filter.



HEPA filters, as defined by the United States Department of Energy (DOE) standard adopted by most American industries, remove at least 99.97% of airborne particles 0.3 micrometers (µm) in diameter. The filter's minimal resistance to airflow, or pressure drop, is usually specified around 300 pascals (0.044 psi) at its nominal flow rate.

The specification usually used in the European Union is the European Norm EN 1822:2009. It defines several classes of HEPA filters by their retention at the given most penetrating particle size (MPPS):

HEPA class retention (total) retention (local)
E10 > 85% ---
E11 > 95% ---
E12 > 99.5% ---
H13 > 99.95% > 99.75%
H14 > 99.995% > 99.975%
U15 > 99.9995% > 99.9975%
U16 > 99.99995% > 99.99975%
U17 > 99.999995% > 99.9999%

Today, a HEPA filter rating is applicable to any highly efficient air filter that can attain the same filter efficiency performance standards as a minimum and is equivalent to the more recent NIOSH N100 rating for respirator filters. The United States Department of Energy (DOE) has specific requirements for HEPA filters in DOE regulated applications. In addition, companies have begun using a marketing term known as "True HEPA" to give consumers assurance that their air filters are indeed certified to meet the HEPA standard.[5]

Products that claim to be "HEPA-type", "HEPA-like", "HEPA-style" or "99% HEPA" do not satisfy these requirements and may not have been tested in independent laboratories. Some of these sub-par quality filters may come reasonably close to HEPA filtration, while others will fall significantly short, making them truly inferior.[6]

Biomedical applications[edit]

Hospital staff modelling a HEPA filter, which can be used if a patient has active tuberculosis


Vacuum cleaners[edit]

HEPA original filter for Philips FC87xx-series vacuum cleaners


Some newer models claim to be better than the first models because of "washable" filters. Generally, washable true HEPA filters are expensive. Some manufacturers claim filter standards such as "HEPA 4", without explaining the meaning behind them. This refers to their Minimum Efficiency Reporting Value (MERV) rating. These ratings are used to rate the ability of an air cleaner filter to remove dust from the air as it passes through the filter. MERV is a standard used to measure the overall efficiency of a filter. The MERV scale ranges from 1 to 20, and measures a filter's ability to remove particles from 10 to 0.3 micrometre in size. Filters with higher ratings not only remove more particles from the air, they also remove smaller particles.



Modern airliners use HEPA filters to reduce the spread of airborne pathogens in recirculated air.[7] Critics have expressed concern about the effectiveness and state of repair of air filtering systems, since much of the air in an airplane cabin is recirculated.

Motor vehicles[edit]

Some[which?] new model cars have cabin air filters that look like HEPA filters but which do not perform at that level. The confusion is perpetuated by guides for changing car filters which misidentify the filters as HEPA filters. The actual performance of these filters is obscured by manufacturers and difficult to evaluate, as they are not rated with the MERV system, though they typically yield MERV 8-equivalent performance.[citation needed]

More recently, the Tesla Model X has been attributed to have the world's first HEPA-grade filter.[8] Following the release of the Model X, Tesla has updated the Model S to also have an optional HEPA air filter.[9]


The original HEPA filter was designed in the 1940s and was used in the Manhattan Project to prevent the spread of airborne radioactive contaminants. It was commercialized in the 1950s, and the original term became a registered trademark[who?] and later a generic term for highly efficient filters. Over the decades filters have evolved to satisfy the higher and higher demands for air quality in various high technology industries, such as aerospace, pharmaceutical drug processing, hospitals, health care, nuclear fuels, nuclear power, and integrated circuit fabrication.

See also[edit]



  1. ^ HEPA Company glossary of terms
  2. ^ Originally 'High Efficiency Particulate Arrestment - see thefreedictionary.com
  4. ^ Gupta (2007). Modern Trends in Planning and Designing of Hospitals: Principles and Practice. Jaypee Brothers Medical Publishers (P) Ltd. p. 199. ISBN 8180619125. 
  5. ^ "Should A True HEPA Filter Mean Anything To You?". home-air-purifier-guide.com. Retrieved 25 March 2016. 
  6. ^ "HEPA-type filter: The Great Pretender". air-purifier-power.com. Retrieved 25 March 2016. 
  7. ^ Boeing Facts on Cabin Air Systems in Commercial Airplanes Archived September 12, 2012, at the Wayback Machine.
  8. ^ "Model X Press Kit - Tesla Motors". teslamotors.com. Retrieved 25 March 2016. 
  9. ^ John Voelcker (12 April 2016). "2016 Tesla Model S gets styling update, 48-amp charger, new interior options, $1,500 price increase (updated)". Green Car Reports. Retrieved 14 April 2016. 

General references[edit]

External links[edit]