What is a True HEPA Filter?

Every air purifier that eliminated dust from the room and caught it on the filters either have True HEPA Filter or HEPA Filter. These are the only ways at this moment to trap airborne particles. Now an average customer that is looking to buy an air purifier may think that these two filters are the same, there is only True word in front one of them. Is that such a big deal?

Two different types of a HEPA filter.
Two Different Types of a HEPA Filter

True HEPA Filter vs. HEPA Filter

Difference between these two filters is enormous. With HEPA Filter you don’t know what your buying, there is no explicit claim what is this air purifier capable. While with True HEPA Filter you know that the air purifier can remove 99.97% of airborne particles down to 0.3 microns. So in other words, if you are looking at the air purifier that says it uses True HEPA Filter, then you know with 100% that the air purifier will remove 99.97% of particles from the air that are larger than 0.3 microns. 

With HEPA Filter you may find claims of 99.9% or even 99.97% removal of airborne particles, but the main info about the particle size is missing. HEPA Filter type air purifiers are using this marketing trick to mislead customers at buying their affordable air purifiers. They aren’t breaking any laws as I know it, but it is not fair to mislead customers. And even if the companies state that their air purifiers are filtering particles down to 2 microns, people are just not educated enough to understand what that means.

Always Buy True HEPA Filter

Because of such marketing tricks, I am highly recommending everyone just to look for air purifiers that use True HEPA Filter. If you are buying True HEPA Filter air purifier, you know what you’re getting, and you have a tested, standardized air purifier. The market is full of True HEPA Filter air purifiers, and I am sure you can find the one that fit your needs. 

Now there are exceptions to the rule to use only True HEPA Filter. If you know that you don’t need to filter all the particles down to 0.3 microns and you actually know the number that the HEPA filter air purifier is suitable for then maybe you can go with a HEPA filter and save some dollars.

How HEPA Filters Work

Both True HEPA Filter and HEPA Filter are working in the same way, the only thing that makes them different is that the True HEPA Filter is standardized and is capable of removing 99.97% of airborne particles larger than 0.3 microns.

The fans in the air purifier pull the air through filters. First, the air goes through pre-filters, which is an excellent filter for every air purifier with HEPA filter to have. Pre-filter will remove large particles which will then not go through HEPA Filter because HEPA filter is made for trapping small particles. Once the particles get caught, they will never be released back to the air again. Some manufacturers claim when HEPA filter gets dirty, it is actually more efficient in trapping airborne particles. Now I am not sure about these claims because we know that HEPA filters need to be replaced every year if not sooner.

After the air leaves HEPA filter, then it is free from airborne particles, especially if the HEPA filter is true, then only filtered air is flowing to the next filter. If there is a carbon filter in the air purifier, it is in some models placed after HEPA filter, but I have seen many air purifiers that have a carbon filter before the HEPA filter. Now I am not sure which is the better position, but somehow logic tells me that air free from airborne particles will be a much better choice for carbon filter whose job is to remove bad odors.


If you want to know more about HEPA filters, it is always good to read articles like this one and get familiar and understand the differences, but if you just want to buy an air purifier and you want to buy the best purifier, then as stated above always look for True HEPA Filter air purifier. True HEPA Filter is standardized, and you know exactly what you get while HEPA Filter you never know how good it will perform. The only thing that you can be sure of is that True HEPA Filter is always better than HEPA Filter.

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