The Facts about HEPA Filters in Air Purifiers

Now more than ever we have customers asking do HEPA filters filter viruses?

We cover this point in many of our other blogs but wanted to give more detail in this blog. 

It would be rare to find an air purifier where the manufacturer will actually tell you the grade of HEPA filter they are using in their purifier according to a particular standard. This is because few air purifiers would pass efficiency testing to a particular recognised standard such as EN1822. Clean Air Delivery Rate (CADR) formulated by the  Association of Home Appliance Manufacturers in the U.S.A. is a lower efficiency test and does not focus on ultrafine particles and therefore is not designed for commercial settings or efficiency on particles the size of viruses.  

The majority of air purifiers you find in stores use synthetic filters and will lose efficiency during the life of the filter, the CADR rating does not take this into account. A tell tale sign a HEPA filter is synthetic is when the manufacturer recommends changing every 6 months of operation. 
What are the Types of HEPA filters? 

Below is a chart on the types of HEPA filters and removal efficiencies according to EN 1822 standards (European Norm). Unfortunately the term HEPA is used loosely because this wide classification covers everything from 85-99.99% efficiencies @ 0.3 microns. While originating from Europe these standards are also used in Australia. 

So when you buy an air purifier the big question is are you buying 85% filtration or 99.99% and how would you know? Many air purifiers will advertise 99.95% efficiency without stating the micron size. The only way to really tell is verify with the manufacturer if it's not clearly written in specifications. 

H13 and H14 HEPA grades are commonly used in medical applications and H13 is the minimum efficiency HEPA filter which can be used in operating theatres in Australia.

When it comes to virus filtration at approx 0.12 microns in size you want to filter which goes as fine as possible. Airborne viruses are usually spread when the virus is aersolised in fine droplets in the air and these are typically 0.5 microns in size and larger. 
At InovaAir® we only use H13/H14 rated HEPA paper in all of our HEPA filters.