Skip to content

Can Air Filters ACTUALLY Trap Particles?


With everything that’s going on right now in the world, you’re probably extra concerned about indoor air quality, and wondering how well your air filter actually works. What percentage of pollutants, allergens, viruses and bacteria is it actually able to trap?

Do you have a HEPA filter?

In order to answer that question, first you need to know whether you have a HEPA filter. What does that mean? Well, HEPA stands for “high efficiency particulate air.” That means that the filter is able to meet the standards that define it as “high efficiency,” or able to trap 99.97% of particles 0.3 microns in size or larger. The measurement term “micron” isn’t very helpful to anyone who’s not a scientist, so to put it in perspective, a human hair is about 50 microns wide. This means one strand of hair is 167 times wider than the teeny, tiny particles a HEPA filter  is able to trap.

How do HEPA filters work?

You may have wondered exactly how air filters work. Are they made out of layers of thick cloth fibers that catch particles – or, are they made of something else? In the case of HEPA filters, they are not made of cloth, but of spun fiberglass! This helps trap even more particles, since the tiny shards of glass form a “maze” – almost like a house of mirrors – that the particles can’t find their way through! If a particle hits a glass fiber or gets stuck in the gap between two fibers, then it’s caught! Actually, it would be even more difficult to navigate than a funhouse, because in a funhouse, the maze passages aren’t too tight for you to squeeze through. With a HEPA filter, however, that’s exactly what you want!

What about particles smaller than 0.3 microns?

It’s pretty incredible that 99.7% of particles 0.3 microns or larger are caught in HEPA filters … but you probably have the nagging thought, what about particles smaller than 0.3 microns? After all, most viruses are smaller than 0.3 microns. Are they escape to get past the filter?

Good news … NO! In fact, a NASA study showed that HEPA filters are great at catching particles as small as 0.01 microns. (That is 5,000 times smaller than the width of a human hair!) In fact, the study showed that HEPA filters are MORE efficient at catching particles 0.01 microns in size, than larger particles! They are even closer to 100% efficient at removing these ultrafine particles.

Here at ThermAll, high efficiency filters are just one of our indoor air quality specialty products. We want to help residents of Yakima, Ellensburg and beyond rest and breathe easier. Just contact us online or call us at (509) 248-8368 , and let our family serve yours.