The true high efficiency filter: what is it and what isn't it

When you study the best air purifiers used at home, you will see the term "HEPA" again and again.Some air purifiers use HEPA filters, while others may use terms like "hepa-like" or "hepa-style."Which of these terms are you looking for, and which are just marketing terms?

We'll take a closer look at what HEPA really means, what filters need to do to meet the standards, and what manufacturers really mean when they call their products "hepa-like."

HEPA standards

HEPA stands for HEPA.HEPA filters typically use a layer of dense fibers to capture particles passing through them.To meet hepa requirements, air filters must trap 99.97 percent of all particles 0.3 microns in diameter.It can trap smaller particles (and often very efficiently capture larger particles), but as the particles get smaller, its efficiency decreases.Note that in Europe, the HEPA standard definition is a little different (if you see a filter that looks like an H13 or U16 rating, the European standard is used) -- in general, the higher the number (regardless of the letter), the better the filter under the European standard.But in this article, we'll focus on the U.S. HEPA standard.

True HEPA - calling the filter True HEPA filter is essentially meaningless because it does not meet any criteria.It can be almost as good as a hepa filter, or it can be completely ineffective.

HEPA Like - this is a variant of the HEPA type, although it is less common.This is just a marketing term, and you should not assume that any filter with this label conforms to the actual HEPA standard.

Ultra-HEPA - a marketing term that claims their air purifiers are "100 times more efficient than HEPA air filters" and can remove particles as small as 0.003 microns in size.This is technically possible, but unlikely in consumer products.

HEPASilent - this is a trademark proprietary filter used by BlueAir, combining electrostatic charges with mechanical filters.Presumably, the charge makes it more likely that the particles will stick to the filaments of the filter, "which allows for the use of less dense filters."

Permanent HEPA filters - these filters are marketed as hepa rated but can also be cleaned and reused rather than replaced.However, we do not recommend cleaning HEPA filters, even though they are intended to be reused, as the cleaning process may cause minor damage to the filters, reducing their effectiveness over time.Envion, Honeywell and Holmes all sell air purifiers with permanent hepa filters.

Absolute HEPA - sometimes used to refer to the same thing as real high performance particulate concentration (HEPA), although sometimes it seems to indicate better filtration capacity, up to 99.999% at 0.3 microns, according to Terra Universal, which makes filters for vacuum cleaners.

You should know more terms related to HEPA

Only the tag True HEPA(sometimes absolute HEPA) has real meaning because it is the only label that claims to comply with the standard.Even so, don't take it all at face value, because there is no formal certification process, so you must trust the manufacturer to have tested their filters to make sure they meet the standards or to look for UL certification marks.Any other changes on the HEPA label, including HEPA type or HEPA type, do not meet the standard.Marketing terms for manufacturer-specific proprietary filtering technologies may or may not meet standards.

Their key is to look for specific Numbers on the label, such as: "99.97 percent of particles are 0.3 microns in size."If the claims on the market are vague, such as "more than 99 percent dust and pollen," they are not really hepa.You should also be skeptical that filters are significantly superior to the HEPA standard.These devices do exist, but mainly in industrial and medical fields, and they may be too expensive for consumer-level air purifiers.

There are a few other terms to watch out for when buying a HEPA air purifier that can complicate matters:

"Clean air delivery rate" - simply how much air passes through the filter - is not a reliable figure.For example, a poorly designed filter with gaps around the filter frame would have a very high CADR number, but as an actual filter would provide little benefit.Meanwhile, a dirty HEPA filter will have a very low CADR rating, but is actually very effective at trapping particles.

"Down to...”-Some air purifiers are marketed as "reducing" particles to a certain size, say 0.1 micron or less.This number is meaningless without any data on the percentage of particles removed.A block of wood can keep particles below 0.1 micron because they occasionally hit the wood, but that doesn't make the wood an effective air purifier.

Activated carbon or activated charcoal -- hepa filters do a good job of removing particles from the air, but they have no effect on gaseous pollutants such as volatile organic compounds (VOCs) or odors.Many HEPA air purifiers claim they can remove these contaminants, but they may be blended purifiers with additional carbon filters, or HEPA filters may be saturated with activated carbon.In any case, this is a completely independent filtering method, regardless of whether the filter meets the HEPA standard.

Remember, just because the word "HEPA" is included in the word on the label does not mean it is a valid HEPA filter.Looking for a true HEPA designation, a UL certification, can provide more legitimacy for the product, or better yet, look at the Numbers presented to you and sold to you.You want to see a filter that blocks 99.97 percent of particles at a size of 0.3 microns -- any other claims are probably just marketing jargon for shameless manufacturers.