HEPA Air Cleaners - The Facts Revealed

HEPA air cleaners were developed during World War II.  This type of system forces air through a special filter that is able to capture any particle up to .3 microns in diameter. (You're talking a millionth of an inch, so this particle is very tiny!) 

With a true HEPA filter, dust, pollen, pet dander, and mold spores are virtually eliminated. Air filters based on 99.97% efficient HEPA have become the industry standard in critical medical and hi-tech applications, because:

• Trapped particles in the filter are never flushed out of the filter.
• The efficiency of the 99.97% efficient HEPA media never decreases.
• The HEPA filtration process is purely mechanical and produces no by-products like ozone.

It is important you not get confused when manufacturers use the expression "99.97% filtration at 0.3 microns". This refers to the air purifier HEPA filter's ability under ideal conditions and may not reflect the actual amount of clean air produced by the system or the general effectiveness of the air cleaning unit. This is why data from independent testing labs is very important information.

"HEPA-type" filters 95% @ 0.3 microns are not true HEPA filters. These are used by air cleaner manufacturers because it allows them to use weaker fan motors. Sometimes it is difficult to figure out whether true air purifier HEPA filters are being used. 

There is a new tendency by manufacturers to misuse the term HEPA for filter technologies that are not performing to the standards of the Institute for Environmental Standards, for example: xxxxHEPA or HEPAxxxx. Again, buyer beware and do your homework!

The downfall to a HEPA air purifier system is that you do need to buy replacement filters. Over time, the additional filters can become very expensive. 

If you have separate filters for the pre, HEPA and carbon filter, these are usually the least expensive to run in the long run. The pre-filter will absorb the largest particulates and save the life of the HEPA filter which is the most expensive element of the machine. 

HEPA air cleaners vary wildly as to the life and cost of their filters which you should check into carefully before you make a purchase. So, while a HEPA air cleaner system may work well for you, you need to look into filter prices before finalizing your decision.

Another word of warning, most HEPA based air purifiers on high fan speed sound like a train going through the room. There is also a great deal of variability in terms of noise. Most manufacturers are dreaming when they describe their air purifier as "whisper quiet" or "ultra quiet". One way to work around this problem is to put the system on high speed when you are out of the room and turn it down to low fan speed when you occupy the room. The best systems have automatic timers which allow you to program the air purifier to go on high when you are not there.