The first HEPA filter (High Efficiency Particulate Air) was designed in the 1940's by the research and development firm Arthur D. Little under a classified government contract as part of the Manhattan Project where the first atomic bomb was developed during World War II. A major advancement in air filtration technology, the filter solved a critical need to control very small particles which had become contaminated by nuclear radioactive sources.
Because of its effectiveness, the filter was originally refered to as an "absolute filter." The generic acronym HEPA came into use some time following 1950 when the filter was commercialized and the original term became a registered tradename.
Today, the HEPA acronym is
used primarilly in the USA whereas Europeans often refer to the
same filter as an S-Class filter.
A True HEPA filter must be proven to trap at least 99.97% of particles O.3 microns in size.
A marketing category, for inferior products has been created: HEPA-like.
These filters have lower pressure differentials, allowing even cheaper casings, motors, and fans to be used.
With the market shakeout of 2009, there has been a rush to cheaper products and reduced support in the air purifier business.
While few new units boast a quality true HEPA, numerous mini-towers, desk/table top, and Made in China HEPA-like filters have appeared.
HEPA-like filters may be made in similar ways to true HEPA filters and may even resemble them visually. The lack of a concise definition means any variety of folded cloth or paper can fit the classification.
A HEPA-like is any filter using construction or materials similar to true HEPA filters, but not performing to standards.
The realization that my Air Purifier was a poor financial purchase didn't happen until 7 months later when I went to buy a replacement filter. This $220.00 machine was now asking me to spend another $120 to replace the filter. The filter was gray and clearly dirty from the auto pollution, pollen and dust in my home air, so I was clearly happy with the results, just not with the financial bath I was about to take.
While HEPA filters are very inexpensive to produce manufacturers know they own you: If you own the air purifier then you're basically stuck buying the replacement filter at the price the company sets for it. Most filters are now made in China.
In Japan consumers are smarter - they look for additional filters included with any air purifier purchase. Because most Americans don't think about "down the road' costs the air purifier makers can charge whatever they want. They often make more money on filters over 2 years than they do on the original air purifier sale itself. The same realization holds true for Auto Makers and inkjet Printer manufacturers: The real money happens in the backend.
Particle tests and comparison charts on this website will show you different models and the most popular filters inside each machine. To compare filter replacement prices see the comparison chart here or via the link below.