We recently put 12 popular vacuums with HEPA filtration systems to the test and the results were eye opening. I need to quickly explain some basic concepts and the test conditions to make the results easier to understand. HEPA just stands for high efficiency particulate air. In the U.S., legally to call it a HEPA filter it must filter particle sizes of 0.3 microns or more.

To give you an idea, the size of a human skin cell is 30 microns. Dust mite fecal matter is 10 microns. Most allergens and bacteria are only about one to three microns. So a HEPA filter at 0.3 microns should be able to filter all of that and more.

The problem is that the vast majority of vacuums are either not sealed or can easily become leaky, causing particles of all sizes to fill up the room that you’re vacuuming, which is not just a problem for allergy and asthma sufferers, it’s bad for everybody.


Our tests involved a liquid based fog machine. The particles it emits are 1 to 5 microns in size. So if we see any fog coming from the vacuum, it either means the vacuum isn’t sealed or the HEPA filter is faulty or both. I checked and serviced every vacuum before the tests, and if they failed, they were serviced again and retested to make sure. But I’m sure there’s a margin for error with these tests so take them with a grain of salt.

Most cheap vacuums don’t claim to have a HEPA filter or a sealed system and they perform as expected. Some, like this inexpensive Hoover, have a HEPA filter but not a sealed system, and in that case, the HEPA filter is doing very little good. Then there are vacuums that have a truly sealed system and HEPA filters, but because of various circumstances, they fail over time.

Take for example this new Shark NV352. It passed the test perfectly but when we tested one of our old NV352s which we used in our cleaning business, it failed despite having been serviced including getting a new HEPA filter.

The reason that some Sharks fail over time in this way is because the HEPA filter casing is subjected to a lot of heat over time and it slightly warps the plastic HEPA filter housing, causing very small gaps in the housing to form. I did find that this could be fixed by putting duct tape around the HEPA filter lid so at least it’s easily remedied.

That being said, when we tested the new Shark APEX, which claims to have better filtration than all earlier models, it passed with flying colors despite me having used it for my professional house cleaning vacuum on a regular basis. I’m not sure if they fixed the issue on the APEX or it just takes more use for the effect to occur.

The next category I found is vacuums that claim to have whole machine HEPA filtration and don’t seem to. Before I badmouth Dyson slightly, we want to point out that both the cordless Dyson V8 and V10 did perfectly on this test. They both were very lightly used vacuums but there seems to be less points of failure for them and I would suspect that they would remain sealed for a long time if not for the life of the vacuum but I’m not sure.

The Dyson Ball Animal 2 claims to have whole machine HEPA filtration, and with our very lightly used unit, we found it was leaking pretty bad on the fog test. Just to be sure, I tested this with a brand-new Dyson Ball Animal 2 and it still failed, not as badly, but there was still quite a bit of leakage. I’m not sure what the problem was. Again, performance reviews on YouTube suggests that the design of the seal of the HEPA filter might be to blame. I suppose I could have gotten a faulty unit but it seems unlikely and it’d be nice to see other people particle test their Dyson Ball vacuums to compare results.

We found that the two bagged vacuums we tested, a very used Hoover Anniversary and the Kirby Avalir 2 passed with no issues whatsoever. While I’ve always preferred bagless vacuums, these tests got me thinking that bagged vacuums that claim to be sealed and use a HEPA filtration bag have a lot less potential failure points since much of the exhaust is processed through the bag. And their claims of sealed HEPA filtration are more likely to be true over a longer period of time.