Air purifiers can be a great addition to your home or work place but only if you choose the right one. Although it is no rocket science, sneaky marketing tactics make it one hell of a job to differentiate between genuine and ineffective models. Same is the case with HEPA-filter based air purifiers.
If you’ve been researching about air purifiers for a while now, you must have come across the terms “True HEPA”, “HEPA-type” and “HEPA-like” quite a few times. Although there’s not much you can make out from their names, there’s a huge gap between the effectiveness of both filter types. Read along to find out which out of them offers better functionality.
What is a True HEPA Filter?
The term “True HEPA” refers to a standard HEPA filter that is capable of trapping suspended particles in the air up to a size of 0.3 microns with 99.97% efficiency. In other terms, if a total of 10,000 particles with a physical size of 0.3 microns or more pass through a standard HEPA filter, only 3 would make it through. For context, a micron (micrometer) is a millionth of a meter. Now that sounds impressive, doesn’t it?
To put the 0.3 micron figure into perspective, consider the following data:
- A human eye can detect particles up to 10 microns
- The average diameter of a human hair is 50 microns
- The average diameter of typical spores and pollen range between 2 to 200 microns
- Very few bacterial species maybe smaller than 0.3 microns
Referring to the above data, it is pretty safe to assume that most indoor pollutants and allergens are larger than the 0.3 micron threshold. This implies, a True HEPA filter can effectively remove indoor pollutants and allergens from the air. As for the remaining bacterial species smaller than 0.3 microns, the HEPA filter can be used in conjunction with a germicidal mechanism like a UV-C chamber to account for bacteria and viruses.
What’s with the 99.97% efficiency?
Standard HEPA filters are marketed with tags like “removes 99.97% particles up to 0.3 microns” all across the states. But how did they get to that number? And does that mean all particles below the 0.3 micron threshold pass through the filter unobstructed? The following graph gives us the answers.
As evident, a standard HEPA filter (True HEPA) works with almost 100% efficiency against particles up to 0.5 microns. But as the particle size further reduces, the efficiency decreases a bit. Surprisingly, the efficiency curve again rises up below the 0.3 micron size.
This implies that the most penetrating particle size ranges in between 0.1 microns to 0.4 microns. All particles above and below this size range are effectively trapped in a true HEPA filter. However, it wouldn’t be pragmatic to market them as an effective means to filter out even lower particulate than 0.3 microns although they do! Hence the number 99.97% against pollutant size of 0.3 microns.
What is a HEPA-type Filter?
A “HEPA-type” filter looks very similar to a True HEPA filter but doesn’t necessarily follow the exact filtration standards. These are not universally standardized for a particular level of efficiency for any minimum particle size retention. However, you may often see tags like “99.9% efficiency” (or something like that) with HEPA-type filters from different manufacturers. These numbers are specific to that model from that manufacturer and not generalized for all HEPA-type filters.
Also, you may not know the minimum particle size for which the filter has the specified level of efficiency unless particularly made clear. In fact, you’ll mostly find an appreciably high level of efficiency for a particular minimum size particle filtration when looking through HEPA-type filters. But most likely, the numbers will nowhere be close to the performance of True HEPA filters and hence you’d be compromising on quality.
For instance, the HEPA-type filter shown above is a replacement filter for the Holmes desktop air purifier. This particular filter is capable of removing particles of size up to 2 microns with an efficiency of 99%. Although these are the most widely marketed specifications of HEPA-type filters, these are not compulsorily the standard performance thresholds of all HEPA-type filters.
You may encounter models that won’t have any such specifications and people will confuse them with the numbers they usually see associated with HEPA-type filters. So, the bottom line is, never invest in a HEPA-type filter or Air purifier unless the model comes with specified satisfactory performance statistics.
Back to the specifications of our example, 99% efficiency for a minimum particle size of 2 microns may allow some allergens through the filter. Consequently, you may not be able to use it effectively if your primary concerns are allergens and other microscopic bacterial species.
Are HEPA-type filters a complete waste of money?
While the performance of a HEPA-type filter is clearly inferior to True HEPA filters, these can still be used effectively at some occasions. For instance, if your indoor air is polluted by larger particles like dust, dust mites, pet dander, pollen and spores, you might as well use a HEPA-type filter to trap such particles without any concerns. Also, these can be bought at relatively lower costs. So, you might consider them if you’re on a restricted budget and the air quality of your room isn’t too bad.
The cost difference between True HEPA Air purifiers and HEPA-type Air Purifiers is however shrinking by the day! As a matter of fact, you get some really reliable Air purifiers with True HEPA filters on a budget these days.
HEPA type vs True HEPA filters – Verdict
True HEPA filters and HEPA-type filters are very difficult to differentiate by just looking at them. Sneaky marketing strategies further add to the confusion. Owing to such standards, people are often misguided to think that HEPA-type Air purifiers are just as efficient as True HEPA Air purifiers while they’re not.
Here’s a brief overview of the most important points that should be remembered when comparing Ture HEPA and HEPA type Air purifiers.
- True HEPA filters are universally standardized to meet the performance threshold of a 99.97% efficient removal of particles with a size of 0.3 microns and above from the air. If you couldn’t comprehend those numbers, believe that it’s pretty impressive and takes out almost all pollutants, potential allergens and microbial pathogens.
- HEPA type filters on the other hand follow no such performance standards. Manufacturers often do not communicate the minimum particle size cleaning ability of their models and when they do; it’s nowhere close to real HEPA filters. Moreover, different manufacturers specify different cleaning potentials for their models making them an unreliable option.
Also Read: The Untold Truth about Ozone Generators.
I’d recommend my readers to opt for a True HEPA Air purifier over other inferior filter based Air purifiers owing to the assured performance standards and credibility.