What Does a HEPA Filter Do?

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What is a HEPA filter and why is it important in a vacuum cleaner? How do HEPA filters work? Are HEPA filters capable of getting rid of mold spores? Should you clean your HEPA filter?  Are HEPA filters suitable for Allergy and Asthma sufferers?

These are the questions that are very often asked.  So, it is time to literally clear the air by answering the ultimate question; what does a HEPA filter do?

What is a HEPA Filter?

In short, the term HEPA stands for “High-Efficiency Particulate Air “or “High-Efficiency Particulate Arrest”, in other words, it is a special type of filter that captures microscopic particles. These particles include things like dust, pollen, mold spores, pet dander, bacteria, smoke, and other particulate matter that comes from indoor/outdoor air pollution.

HEPA filters, or air cleaners, are not only great for people with allergies or asthma but also those who enjoy healthier living and a cleaner home.

How is a HEPA filter different from other Filter Systems?

A standard air filtration system is only able to eliminate medium to larger particles from the air because they are not able to completely remove tiny micron size particles as a HEPA filter does.  To put it into perspective, the human eye can detect a particle that is approximately 10 microns.  Pollen and Plant spores are naturally in this range and hence visible to our eye with some precise detection.  Airborne diseases like allergies and influenza can easily be spread if proper filtration is not used.

What Does a HEPA Filter Do?

what does a HEPA filter doHEPA filters are capable of capturing airborne microscopic particles that will usually pass through most filtration devices.  HEPA filters can capture 99.7% that’s 9,997 out of 10,000 particles that are as small as 0.3 microns in size.  To put that into perspective, 0.3 microns is about three hundred times smaller than the diameter of human hair, and about 30 times smaller than what we can see with our own eyes!!

Are HEPA filters capable of getting rid of mold spores?

YES.  The HEPA filter is exceptionally effective in capturing and trapping mold spores because they are between 2-20 microns in size.  In fact, HEPA filters are the only kind of filter that will trap these airborne particles.

Are HEPA filters suitable for Allergy and Asthma sufferers?

Because of their ability to capture and trap airborne allergens, dust and dirt particles, HEPA filters are GREAT for allergy relief, asthma support, cleaner homes, and overall healthier living.  If you use a conventional vacuum cleaner without A HEPA filter, most of the particles below 5 microns will become airborne and potentially affect a persons breathing ability.

Therefore, it’s really important to get a vacuum cleaner that has a HEPA filter because you will significantly reduce the number of allergens that become airborne in your home.

What can’t HEPA filters capture?

The only drawback to HEPA filters is that they can’t capture viruses, odours, or chemical gases.  Those particles are too small and therefore require another kind of filter to trap them.

How do HEPA Filters differ from one another?

When shopping for a HEPA filter, you will come across a few different terms because of their difference in functionalities.

These terms are mostly:

  • HEPA
  • True HEPA
  • HEPA-like
  • HEPA-type

Understanding the difference is huge because they mean different levels of filtration. For example, a True HEPA filter is the best type because it is certified to capture 99.97% of particles as small as 0.3 microns in size.  This includes the widest range of indoor contaminants.  In contrast, the HEPA-like, HEPA-type, and HEPA filters can only capture particles as small as 2 microns.  That’s more than a 500% difference in efficiency because these filters miss many ultra-fine pollutants.

So, we recommend that you always buy a vacuum that uses a True HEPA filter, especially if you suffer from allergies and asthma.

How do HEPA filters work?

Think of a thick sheet of paper with very tiny holes that filter out pollutants. Only little amounts of air can pass through this paper. If the size of the sheet was doubled, it would be possible to get 2 times the airflow and 2 times the filter life.

A larger surface area would make for a more productive filter. So, instead of increasing the dimensions of the sheet itself, the surface area of the sheet is increased by being folded back and forth many times.  Air is forced to go through the sophisticated network of fibres and in the process, particles hit the fibres and stick.

HEPA filters can filter out the larger particles like dust naturally.

The HEPA filtration system is a 3-step process. The process starts by filtering out larger particles like a sieving process.

The air coming out than flows through a finer type of mesh fibre that will trap most of the finer particles.

Finally, the air then moves through the filter where particles are then caught by the fibre. When the air comes through the other side of the HEPA, it removes 99.97% of particles from the air.

HEPA Filter Maintenance

When to clean it?

If you use your HEPA filter device and/or vacuum regularly, check it once a month.  If you find yourself using it more, check it once every 2 weeks.

How to clean it?

If you notice dirt or dust on the surface, it is a good time to clean your HEPA filter. Simply run the filter under warm water and let them air dry completely. You can also blow the HEPA filters out by using an air compressor or a can of air.  Blowing them out helps lift away that dirt and dust deep down in the grooves of the HEPA filter.

When to replace it?

With regular household use, we recommend replacing the filter once a year. If you vacuum a lot, considering replacing it every 6 months. If you keep up on checking and cleaning them regularly the filter will last longer.


  • The HEPA filter was first developed during the Second World War, and used to capture radioactive particles at facilities where atomic bomb components were being manufactured?! 
  • HEPA filters work more efficiently as they get dirtier?!

A Few Points To Note

Remember to consider the cost value associated with HEPA filters/systems because replacement filters can be very expensive. Therefore, always try to complement your HEPA filter system/s with other devices and/or appliances that also work to reduce viruses, germs, mold and other airborne particles so that it is not working in overdrive. These items are outlined in our Best Vacuums For Allergies and Asthma article, and include the following:

So back to our original question, what does a HEPA filter do? As you have now read, a HEPA filter, in particular a True HEPA filter, is your absolute must have when selecting the appliances and devices to achieve the ultimate clean and healthy home.

Happy vacuuming X


  1. I have heard of these filters but until reading your article I really knew very little about them, you did an awesome job on sharing about Hepa filters and I have been considering if I should invest in one in the future.

    I only have once concern with the price of these filters how effective are they with a home with long-haired dogs, I know many pet-friendly products I have bought in the past did not live up to their promises with my dog with long hair that sheds almost constantly


    1. Hi Jeff, glad I could help! HEPA filter replacement is certainly a case by case scenario. If you have a large home, vacuum often, have a couple of pets living inside and no other methods of removing pet hair and/or allergens from your home, the recommendation is to replace your HEPA filter every 2-3 months. If you clean and maintain your vacuum and filters often, you could get away with an extra month.

      Use that scale as a measure to determine your situation, for example, if your home is small and you seldom vacuum, you can extend the life of your HEPA filter from the recommendation.

      I hope that helps Jeff, good luck!

  2. Thanks for the information you provided on HEPA filters. I always wanted to know what it’s capable of and now I do because of your article. I did not know that a HEPA filter can catch bacteria but not viruses. That’s important now a days with the corona virus spreading around the globe. All those people who wasted their money buying masks. Anyway, great read. I did enjoy reading your article, and thanks for sharing.


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