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What is a HEPA filter?

What is a HEPA filter? What does it do and is it enough to protect us?

April 20, 2022

What does a HEPA filter do?

A HEPA filter is capable, by definition, of capturing at least 99.97% of particulate 0.3 microns in diameter.

What is a HEPA filter made of?

HEPA filters are composed of a mat of randomly arranged fibres. The fibres are typically composed of fiberglass and possess diameters between 0.5 and 2.0 μm.


What are the benefits of HEPA filters?

When you invest in a HEPA filter you are buying technology that has been tested and approved against a standard. This ensures the quality and reliability of the filter to remove even the tiniest airborne particles. Air filtration is actually more important than many of us realise as indoor air contains many different irritants and pollutants. A correctly chosen HEPA filter can ensure these pollutants are removed efficiently, vastly improving the quality of air you breathe. Pollutants can include pollen, dust mites, pet dander, viruses, bacteria and other pollutants.


Is HEPA enough?

Despite the effectiveness of HEPA filters to capture pollutants, these filters also provide a potential ‘breeding ground’ for particulates within the unit. Thus, it is crucial for the HEPA within a unit to be coated in an antimicrobial preservative layer, thus inhibiting the growth of bacteria on a filter.


Despite the effectiveness of HEPA filters, even at very small impurity levels, these filters do not kill any pathogens. Some air purifiers include UV-C technology to denature viruses and bacteria, essentially killing the particles trapped by the filters.


UV-C  irradiation involves  high-energy  wavelengths being  emitted via a special UV bulb from deep within in the purifier unit which provides the ability to damaging the genetic material (DNA or RNA) of microorganisms such as  bacteria and  viruses,  deeming them  no  longer able  to  perform their  vital functions.   Such technology,  known  as ’germicidal  irradiation’,  is  an  essential part of any full air purification solution and is the most widely adopted method of control for contaminants in US health centres.  Many studies confirm the use  of  this technology as an important addition  to  any purification  unit,  whilst highlighting that such a process bore no utilisation risk to the user.


What is a HEPA-like filter?

Readers should be aware of the marketing tools used by companies to advertise their air purifiers as being ”HEPA-type,” ”HEPA-like,” or ”99% HEPA,” as these refer to HEPA filters which perform below industry standards outlined above.


Do HEPA filters need cleaning?

All air cleaners require periodic cleaning and filter replacement to function properly.  Follow manufacturer's recommendations on maintenance and replacement.