Ratings decoder
HEPA, True HEPA, and Words That Look Like Them
One of these is a filter grade with a definition behind it. The other two are phrases printed on boxes.
The same thing, read twice — GermGuardian FLT4825 Filter B
What the listing states
The listing claims removal of 99.97% of pollutants, and names seven machines the cartridge fits by model number.
What that figure is and is not
A capture percentage of that kind describes a filter medium tested under specified laboratory conditions at a specified particle size. It is the seller quoting a media grade, not a measurement of what happens in a particular room, and it is not a health claim.
Both readings come from the listing for GermGuardian FLT4825 Filter B, which states: listing states it fits AC4825, AC4300, AC4850, AC4880, AC4900, CDAP4500 and AP2200, and claims removal of 99.97% of pollutants — quote that figure as a listing claim only.
What is actually going on
HEPA is a filter grade. The figure attached to it describes how much of a challenge aerosol a medium captures at the particle size where it performs worst, under conditions the test method specifies. That is a real, defined thing, and a filter medium that meets it has been through a real procedure.
True HEPA is not a separate grade. It is a phrase sellers adopted to distinguish their product from things marketed as HEPA-type, HEPA-style, or HEPA-like — phrases that signal a medium resembling the real grade without stating that it meets it. None of those three phrases has a definition behind it.
This matters most when the number gets detached from the filter and attached to the appliance. A filter medium capturing a given fraction of a test aerosol in a laboratory rig says nothing on its own about what a room contains after a purifier has run in it for an evening. Room size, how much air the machine moves, whether the doors are open, and how the air gets to the machine all sit between the two.
This site quotes capture figures where a listing states them, and it quotes them as listing wording every time. It does not restate them as measured outcomes, does not compare products on them, and does not attach any health meaning to them. There are no claims here about preventing illness, filtering out viruses, or relieving symptoms, because no such claim can be supported by a product listing.
For general information about air cleaners in homes, the EPA publishes a guide written for exactly this question. For anything about your own health, a physician is the right place to take it.
Lined up against each other
| Phrase you will see | What stands behind it | How this site treats it |
|---|---|---|
| HEPA | A defined filter medium grade with a specified test method and a specified particle size. | Reported where a listing states it, as a grade the listing claims. |
| True HEPA | Marketing wording adopted to distinguish from HEPA-type products. No separate definition. | Quoted only as listing wording, never treated as an additional grade. |
| HEPA-type, HEPA-style | Wording that signals resemblance without stating the grade is met. | Quoted as listing wording, and the absence of a grade claim is worth noticing. |
| 99.97% of pollutants | A capture figure the seller publishes for the medium. | Reproduced as a listing claim only. Never as a result in a room, never as a health claim. |
| AHAM Verifide | A voluntary verification program run by an industry association. | Reported where a listing states it, with a link to the program directory. |
What this scale does not tell you
- What the air in your room will contain after running a machine, which no filter grade predicts.
- Anything about health, illness, or symptoms. This site makes no such claims about any product.
- Whether a purifier is sized for the room it is in — that is a separate question about air movement.
- Whether a third-party cartridge meets the grade its listing describes, since the appliance maker has not verified it.