What Is a True HEPA Filter? True HEPA vs HEPA-Type

What 'True HEPA' points at#

The definition behind the phrase is the published standard: a HEPA filter captures at least 99.97% of particles at 0.3 micron. "True HEPA" is the industry's way of saying the filter inside meets that definition rather than merely enjoying the vocabulary.

It is a capture standard for the media. Like any filter claim, it says nothing about how much air the machine moves through that media.

The shading around the word#

"HEPA-type", "HEPA-like" and "HEPA-style" have no standard behind them. They are not lower tiers of the definition; they are phrases with no definition at all, free to mean whatever the printing budget allows.

The shading works by proximity. The real number sits on the same box as the vague words, and the eye does the transfer. Read the label as a lawyer would: either the 99.97% figure is claimed, or it is not.

Does it matter?#

Yes, as marketing shading of a real standard, which is a better situation than most marketing enjoys. "True HEPA" points somewhere checkable; the imitation phrases point at the checkout.

But even the honest label is only the filter. The number to trust when choosing the machine is still the CADR, because CADR measures the filter and the fan together. A true HEPA filter in an undersized unit is a small purifier with good taste in media.

What to check on the box#

• The full definition stated plainly: 99.97% at 0.3 micron. Half the phrase is not the phrase.
• Which filter words are definitional and which are decorative.
• A published CADR, the filter is the stage, the delivery is the size.
• Replacement filters that meet the same definition, actually in stock: find replacement filters that meet the definition.