What Is A HEPA Air Purifier?
Short answer
How Many Types of HEPA Filters Are There?
As stated by the Institute of Environmental Science and Technology (IEST), there are 6 types of HEPA filter from A, B, C, D, E & F. Each has its own characteristics and performance as shown by the table below.
| Filter Type | Penetration Test | Scan Test | Efficiency Ratings | ||
|---|---|---|---|---|---|
| Method | Aerosol | Method | Aerosol | ||
| A | MIL-STD 282 | Thermal DOP | None | None | 99.97%/ 0.3 um |
| B | MIL-STD 282 | Thermal DOP | None | None | 99.97%/ 0.3 um |
| C | MIL-STD 282 | Thermal DOP | Photometer | Polydisperse DOP | 99.99%/ 0.3 um |
| D | MIL-STD 282 | Thermal DOP | Photometer | Polydisperse DOP | 99.999%/ 0.3 um |
| E | MIL-STD 51477 or MIL-STD F51068 | Thermal DOP | Photometer | Polydisperse DOP | 99.97%/ 0.3 um |
| F | IES-RP CC007 | Open | Particle Counter | Open | 99.999%/ 0.1 to 0.2 um |
Confuse? You don’t have to. Skip all that and focus on the next 2 types that we about to introduce. True HEPA AKA genuine HEPA filter VS HEPA-type filter. The former is the superior one while the latter is the inferior one. So let’s talk about the superior True HEPA filter. It is the one you should be looking has it matches the strict U.S. Department of Energy (DOE) standard. A True HEPA filter will be able to capture at least 99.97% of the airborne particles as small as 0.3 microns. Many premium air purifiers will be equipped with this type of filter but occasionally you do see it in cheaper models. As for the inferior HEPA-type filter, it can remove at least 99% of the airborne particles as small as 2 microns. Due to the less density, this type of filter is usually in the cheaper, compact air cleaner. You might even see it in a permanent filter air purifier.
In conclusion, do go with air purifier with True HEPA filter. Only go with HEPA-type with you are on a tight budget and know what you are getting at. If you are not sure what you are getting at, read the label, reviews, or comparison website like yours truly.
The Pros of a HEPA Air Purifier
First of all, availability is not a problem as many big brands carried it. IQAir, Blueair, Winix, Airmega, Austin Air, and Honeywell all focus on HEPA technology. Second, HEPA filtration exists since 1950. It is proven and certified to be efficient according to industry standards. Third, HEPA air purifier is excellent in trapping microscopic particles including germs. It will also trap dust mites, pollen, mold, mildew, pet dander, and bacteria. If you are an allergy-prone person, have indoor pets or asthma, go for it.
The Cons of a HEPA Air Purifier
Cost is one thing as the filter typically has a year’s lifespan. You will have to replace it annually or when the filter is exhausted. A true HEPA filter cannot remove smoke, chemical fumes, and odors. You will need an activated carbon filter or equivalent filter to do that. Unlike UV-light, the HEPA filter does not eliminate viruses and bacteria. The allergens might still spread across the room if the substances break down. Also, microorganisms like mold may reproduce and grow on the filter. Preventable if the filter has an antimicrobial coating.
So HEPA air purifier Yay or Nay
Yay if you don’t mind the cost of ownership especially for the later years. Nay if you only want a semi-effective air cleaner that does not require filter replacing. There is plenty of good air purifier with a True HEPA filter. They might not be the cheapest, but they are definitely worth every penny. You just need to make sure it is the genuine type and not be fool by any marketing gimmick.
HEPA stands for High-efficiency Particulate Air or in some cases, High-efficiency Particulate Arrestance. This is a recognized filter produced, tested and credited with IEST, UL standards. You can find HEPA filters in many of the household products e.g. vacuum cleaners, air-con, HVAC system or an air cleaner.
