True HEPA Air Purifiers & Filtration Explained

Air Purifiers & True HEPA Filtration Explained

Search on Amazon for “home air purifier,” and you click through “over 3,000 results.” How does a consumer even begin to choose?

Most consumers have heard the acronym HEPA (high-efficiency particulate air) filters in advertisements from manufactures of vacuum cleaners and air purifier products. But it’s easy to be confused and gloss over the fine print.

The U.S. Department of Energy (DOE) technical standard specification for HEPA filters used by DOE contractors defines a HEPA as the filter shall exhibit a minimum efficiency of 99.97% at a test aerosol diameter of 0.3 micrometers (μm) in diameter from the air that passes through the filter.

Pay special attention to the last sentence because it is the numbers 99.97% and 0.3-micrometer that tell the only story that matters when it comes to home air purification.

Spin or No Spin

Among the thousands of HEPA-labeled home air purification devices on the market, manufacturers have added finer, if not sometimes misleading, terms on their packaging.

Not liking to be spun, I pointedly asked Haylie Morales, associate product manager at Sharp Home Electronics Company of America, what was up with “True HEPA,” a term that Sharp and other manufactures use on packaging.

Morales explained, “True HEPA is the marketing term for ‘HEPA Class H14’, which captures up to 99.975% of airborne particles measuring 0.3 micrometers (μm) in diameter that pass through the filter.” Ah-ha—I knew it was a marketing term!

To be fair, the manufacturers that use the term “True HEPA” are doing so because there are several misleading terms used by others such as “HEPA-type,” “HEPA-like,” HEPA-style,” or “99% HEPA.” “These would represent filter-based systems that do not satisfy the HEPA standard or may not have been independently tested,” she says. “Manufacturers are legally required to label retail cartons to reveal efficiency. You cannot say that your filter is ‘True HEPA’ if it is not.”

Not Splitting Hairs

Particulate matter (PM) are particles (solid or liquid) that move through the air and are measured in micrometers (μm), or commonly referred to as a micron. The width of a single human hair ranges from approximately 10 to 200 μm. A True HEPA filter within an air purifier captures particulate matter as small as 0.3 μm.

Take a look at the chart below from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and choose which contaminants you are okay with having in your home, and then look at the corresponding minimum particle size (μm).

Contaminants by Particle Size and Typical Application

Min. particle size Typical controlled contaminant Typical Application
> 10.0 μm Pollen, dust mites, cockroach debris,
sanding dust, spray paint dust, textile fibers, carpet fibers
Residential window AC units
10.0–3.0 μm Mold spores, dust mite debris,
cat and dog dander, hair spray, fabric protector, dusting aids, pudding mix
Better residential, general commercial, industrial workspaces
3.0–1.0 μm Legionella, humidifier dust, lead dust,
milled flour, auto emission particulates,
nebulizer droplets
Superior residential, better commercial, hospital laboratories
1.0–0.3 μm Bacteria, droplet nuclei (sneeze), cooking oil, most smoke and insecticide dust, most face powder, most paint pigments Hospital & general surgery

Most would prefer the Indoor Air Quality (IAQ) in their home to be as clean as was needed in a hospital’s general surgery room. Only a True HEPA filter will capture all the contaminants listed in each row, right down to 0.3 μm bacteria.

Now you’re adequately armed to shop for a home air purifier!

Featured in this Article


FPF50UW
SHARP HEPA AIR PURIFIER WITH PLASMACLUSTER® ION TECHNOLOGY

The Sharp FP-F50UW Plasmacluster Ion Air Purifier with True HEPA Filtration is ideal for small rooms in your home. This air purifier model effectively reduces pollen, dust, pet dander, smoke, germs, bacteria, viruses, odors, mold, and fungus in your living space. There is a dual stage filter system including an activated carbon filter and long-life True HEPA filter, which captures 99.97% of particles as small as 0.3 microns from the air that passes through it. Patented Plasmacluster Ion Technology disperses positively and negatively charged ions throughout the room to safely break down microorganisms and odors (even those trapped in fabric, carpeting, and drapery!). It is an ideal solution for allergy sufferers, asthmatics, pet owners, and smokers, and best used in a bedroom, living room, study, or exercise room. There are 3 manual fan speeds. The air purifier unit has LibraryQuietTM operation (as quiet as 29 decibels, or the sound of rustling leaves) and is ENERGY STAR(R) rated, so you can run the unit continuously while saving money and energy.

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FPK50UW
Sharp HEPA Air Purifier with Plasmacluster® Ion Technology for Medium Rooms (FPK50UW)

A breath of fresh air in any medium-sized room, the Sharp FPK50UW Plasmacluster Ion Air Purifier with True HEPA Filtration effectively reduces pollen, dust, pet dander, smoke, germs, bacteria, viruses, odors, mold, and fungus in your living space. There is a three-stage filter system including an activated carbon filter and long-life True HEPA filter, which captures 99.97% of particles as small as 0.3 microns from the air that passes through it. The micro screen pre-filter for larger particles is washable and helps to extend the life of your filters.

Patented Plasmacluster Ion Technology disperses positively and negatively charged ions throughout the room to safely break down microorganisms and odors (even those trapped in fabric, carpeting, and drapery!) The FPK50UW air purifier is an ideal solution for allergy sufferers, asthmatics, pet owners, and smokers, and best used in a bedroom, living room, study, or exercise room.

“Plasmacluster Express Clean” gives you sixty minutes of high-density Plasmacluster Ion production and high-fan speed for an extra boost of clean when you need it, and a hands-free return to the prior mode when complete. The unit has LibraryQuiet™ operation (as quiet as 22 decibels, or the sound of rustling leaves) and is ENERGY STAR® rated, so you can run the unit continuously while saving money and energy.

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About Sharp Home Electronics Company of America (SHCA)

SHCA is the U.S. Consumer Products Group of Sharp Electronics Corporation, the U.S. sales subsidiary of Sharp Corporation, a worldwide developer and manufacturer of one-of-a-kind premium technology products. SHCA includes the manufacturing of certain Home Appliances in Memphis, TN, together with the sales & marketing and servicing of Home Electronics in the United States.  Leading products include Sharp Carousel(R), Microwave DrawerTM, SuperSteam+TM ovens, and Plasmacluster(R) Ion air purifiers. Sharp Corporation was named one of the 20 Most Loved Companies globally, received a 2018 Thomson Reuters TOP 100 Global Technology Leader Award, and appears on the Forbes America’s Best Employers 2017 list.1

Sharp, Carousel, Microwave Drawer, SuperSteam+, Plasmacluster, Healsio, and all related trademarks are trademarks or registered trademarks of Sharp Corporation and/or its affiliated companies. All other trademarks are the property of their respective owners.

1 Sources: Buyology Inc., 2012; APCO Worldwide, 2013; Forbes, 2017; thomsonreuters.com

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