Here’s one question that Dustfreerooms.com’s readers frequently ask: True HEPA vs. HEPA-Type Air Filter, which is better? The difference between True-HEPA and HEPA-type air purifier filters isn’t always clear. Some marketers use vague marketing tactics to coax consumers into believing HEPA-type is the same as true HEPA. But there’s a difference between these two filter types. True HEPA air cleaners filter indoor air more comprehensively compared to HEPA-type options.
Related Post: ULPA vs HEPA Filter: Which Is Better?
What is a HEPA Filter?
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HEPA stands for High-Efficiency Particulate Arrestance. A HEPA filter is a mechanical filtration medium made by compressing many layers of fibers. It captures a whole bunch of airborne particulates including mold spores, bacteria, pet dander, viruses, dust mites, and pollen.
There are two kinds of HEPA filters namely True HEPA and HEPA-type/HEPA-style. True HEPA filters have a demonstrably better filtration efficiency compared to HEPA-type filters.
Do HEPA Filters Remove Particles Smaller Than 0.3 Microns?
Yes, certified HEPA filters remove particles smaller than 0.3 microns in size. Actually, they remove smaller particulates even more efficiently according to the US Environmental Protection Agency. Of course, these high-efficiency filters remove larger particles even better. Because the larger the size of the airborne particle, the harder for the irritant to pass through the filter.
What is a True HEPA Filter?
A True HEPA filter is a mechanical filter that captures at least 99.97% of particles with a diameter of 0.3 microns. The 99.97% particulate removal efficiency rate is the US standard. The oldest US HEPA filtration standard, MIL-STD-282, dates back to 1956.
Its latest version is the MIL-STD-282, Revision B, December 22, 2015 standard. It governs all performance tests relating to protective clothing, gas-mask components, and filters.
The European standard is slightly less stringent. Air filters made per the European standard remove at least 99.95% of 0.3-micron pollutants. But that’s hardly a difference in filtration efficiency.
What Is a HEPA-Type Filter?
A HEPA-type filter is a mechanical filter that removes 99% of particles with a 2-micron diameter. Both filters have a pleat-like design, but they’re not made of the same materials. HEPA-type filters are made of mostly fiberglass vs. a mix of cellulose (20%) and polyester (80%) for True HEPA.
Another difference is that HEPA-style filters aren’t as dense as their True HEPA counterparts. Unsurprisingly, True HEPA filters trump HEPA-like ones in terms of capturing ultrafine particles.
HEPA vs. HEPA-like Filters Similarities
- Both based on the HEPA standard
- Same filter construction design
- Both trap particles using the same methods namely inertial impaction, sieving, diffusion, and interception
- Both trap relatively large particles well
- Neither filter type shines at removing smoke particles, VOCs, and pet odors
HEPA vs. HEPA-like Filter Differences
True HEPA filters are:
- Made of cellulose & polyester vs fiberglass for HEPA-style
- Not washable while you can wash or vacuum HEPA-type filters
- More expensive and usually used in top-of-the-line devices versus HEPA-style in lower-priced options
- Offer more comprehensive filtration compared to HEPA-like
When Were HEPA Filters Invented?
The 1940s saw the devastating World war II. But this period also witnessed the discovery of the HEPA filter. The US through the Manhattan Project created the first-ever HEPA filter to capture radioactive particles.
The Manhattan Project consisted of two entities namely the US National Defense Research Committee and the US Army Chemical Corps. Commercial production of this particle-capturing filter didn’t start until the 1950s though.
Why is MPPS Fixated on 0.3-micron Particles?
Have you ever wondered why filtration efficiency test methods for HEPA filters focus on 0.3-micron particulates? A highly regarded scientist, Irvin Langmuir, identified 0.3-micron particles as being exceptionally challenging to capture. Also, the Nobel Laureate in Surface Chemistry determined that this particle size was the most penetrating of all.
The EPA uses the term MPPS (Most Penetrating Particle Size) to describe these hard-to-remove pollutants. According to this scientific paper, 0.3-micron particulates encounter the least resistance while passing through HEPA filters.
How HEPA Filters Work
A motorized fan pulls in dirty air which then passes through a dense layer of closely woven fibers. These fibers capture airborne contaminants such as dirt, mold pet dander, grass pollen, and more. According to BOFA International, an expert in fume extraction technology, HEPA filtration takes place through four different processes namely inertial impaction, sieving, diffusion, and direct particle interception.
Inertial Impaction
As the airstream approaches the dense fibrous filter, it changes course slightly. As for heavier particles in the airstream, they’re heavy enough to keep moving forward without changing direction. Naturally, they end up smashing into the filter’s fibers and inevitably stop.
Particle Sieving
HEPA filters capture the vast majority of air contaminants by sieving them between individual fibers as the air passes through. Think of how a normal sieve works. It filters out materials that are too large to fit in its tiny holes while letting everything else stream right through.
Direct Particle Interception
Direct interception works similar to inertial impaction, but there’s a slight difference. In this process, medium-sized particles get captured. These particles aren’t heavy enough to keep streaming forward even when the fluid they’re part of changes direction. Also, they’re not small enough to keep moving in a haphazard way within the airstream.
Some of these medium-sized particles pass through the filter in the airflow. But some hit fibers along the way and get stopped.
Diffusion
Diffusion helps remove the smallest particles in the dirty airstream. These tiny particles keep waltzing around in the airstream in a Brownian Motion-like manner. As a result, most of them end up hitting the fibers and sticking to them. Do you now see why the EPA says that HEPA filters remove the smallest particles even better than bigger ones?
What Do HEPA Filters Remove?
HEPA filters are exceptionally good at removing solid particulates. They’re the best technology for getting rid of pet dander, mold spores, dust particles, tree pollen, grass pollen, bacteria& viruses (especially those with UV-C filtration), and even smoke particles. But while this highly effective filter captures tobacco smoke particles, it doesn’t remove the actual smell. HEPA filters have received recognition for their ability to capture both PM2.5 particles and the larger PM10 particulates.
HEPA Filter Limitation: They Suck at Smoke and VOCs Removal
Both True HEPA and HEPA-type filters don’t capture every single contaminant in the indoor air being filtered.
Some particles such as Volatile Organic Compounds, kitchen cooking smells, Marijuana smoke, tobacco smoke, and wildfire smoke, are too small and pass right through these filters.
But does that mean HEPA air purifiers don’t remove smoke? No, decent HEPA units can and do remove a substantial amount of smoke particles and even VOCs from the air. But they don’t rely on mechanical air filtration to do that. Instead, these devices turn to odor removal filters or activated carbon filters to tackle these particles.
Pro Tip: Not all HEPA air cleaners marketed as great odor eliminators are nearly as good. The best options for smoke removal typically have a relatively thick carbon filter. If a particular unit offers no more than a thin activated charcoal layer, you’re looking at the worst-possible odor eater.
Types of HEPA Filters
There are at least 6 filter types namely HEPA filter types A, B, C, D, E, and F. These types, though distinct, have almost the same minimal efficiency rating. This table lists all 6 filters types as well as each type’s efficiency rating.
HEPA Filter Applications
Medical facilities such as hospitals use HEPA filters to keep allergens, germs, and other contaminants under control. They’re also used in the aviation and automotive industries (think of cars and planes). Others include the pharmaceutical industry, the semiconductor industry, and the computer industry among others.
Are Some HEPA Filters Better Others?
Yes. Not all HEPA filters are created equal. In fact, there are different grades of HEPA filters. Standard HEPA filters live in the H10-H12 HEPA grade neighborhood.
Then there are HEPA grades H13-H14, also called medical-grade filters. Medical-grade HEPA filters, usually advertised as H13 filters, supposedly outperform regular HEPA filtration-wise.
Unfortunately, there’s no way of knowing for sure whether the filter in a particular room air cleaner is actually H13. Either believe what the manufacturer says and fork over more or stick to regular HEPA.
Which Brands Make HEPA-Type Filters?
Many air purifier brands today make both True HEPA and Hepa-type devices. A brand might make a bunch of True HEPA models for those who want nothing short of the best. The same company might also manufacture a couple of HEPA-like models to serve price-conscious consumers who still prefer HEPA-standard filtration.
For example, Honeywell makes True HEPA models such as the Honeywell 50250-S, Honeywell HPA300, HPA200, HPA100, and Honeywell HPA105TGT.
Honeywell also makes a couple of HEPA-type models such as the Honeywell HFD-120-Q, Honeywell HFQ-010, and Honeywell HFD-130. Other brands making both filter types include Boneco Therapure, Winix, and a few others. Here’s a list of purifiers with washable or permanent filters.
But if you’re looking for a brand that makes only True HEPA purifiers, consider companies such as Airthereal, Airthereal, Austin Air, IQAir, Medify Air, Levoit, and a few others.
Conclusion:HEPA-vs. HEPA-Type Filters
Both true HEPA and HEPA-type filters are fantastic options for removing common indoor air pollutants.
HEPA-type filters can be a worthwhile option if you’re looking to save some money. But they’re not as good as true HEPA air cleaners in terms of filtering out harmful pollutants from your indoor air.
