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HEPA Air Purifier Reviews: A Comparison of HEPA Filters

A HEPA (High Efficiency Particulate Air) filter is a mechanical filter that traps airborne particles as they pass through an air purifier.  A true HEPA filter is rated to remove 99.97% of all particles that are 0.3 microns in size or larger.  A micron, also known as a micrometer is one millionth of a meter.  As a reference point a human hair is approximately 60 microns in diameter and a grain of pollen is 5 microns.  90% of all airborne particles are less than 0.1 microns in size and the challenge with air purifiers is that most of these particles are too small to see so it's hard to tell how well it's working visually.  The light weight and low mass of these particles allow them to be suspended in the air for extended periods of time and most likely to be breathed deep into your lungs. The larger and heavier dust type particles tend to settle on the ground much more quickly and harmless to your system.

In a review of air purifier technologies, HEPA air purifiers are the recommended filtration method of leading government agencies such as the American Lung Association, Department of Homeland Security and EPA.  This favorable review is due to the high efficiency of the HEPA filter, it's ability to remove most of the smallest, most dangerous particles and the inherent ability to improve performance over time.

Recommendation: to best enjoy the benefits of cleaner air, find a purifier with a high efficiency filter, good air flow and reasonable noise level.

HEPA Air Filter Advantages

HEPA air filters are rated highly due to their superior ability to remove a very high percentage of particles with each pass of air through an air purifier.  If you suffer from allergies or asthma a HEPA air purifier is always the best choice since its filtration is designed to remove the tiny particles that trigger an allergic reaction. The particle removal performance is significantly better with a HEPA filter as compared to the ionic and electronic air cleaners.  In addition, HEPA air filters often improve performance over time whereas the filterless technologies (ionic, electrostatic) see a decrease in performance over time as the electronic plates become dirty.

A HEPA filter does not generate ozone. In late 2010, the state of California required all air purifiers to be at a safe ozone level and this has dramatically increased the percentage of air purifiers sold with the HEPA technology.

HEPA Air Filter Disadvantages

The primary downside to a HEPA air filter is the noise level associated with moving sufficient air through the HEPA filter for a given room.  Noise level can be subjective and some users commented positively on the white noise effect but we also found some users that did not like the noise level on the higher fan speeds of a HEPA air purifier.  Noise levels are measured in decibels (dB) and provide a good reference point when comparing HEPA air purifier models as well as consumer reviews. Since the HEPA filter media is dense it can generate various levels of white noise. Operating a HEPA air purifier on a lower fan speed will result in lower noise levels that can be silent however there is also a reduced air flow associated with the lower fan speed.


If you are looking for a solid solution to improve your indoor air quality then a HEPA filter air purifier is the best choice. The better HEPA air cleaners cost more than $200. The purpose of an air purifier is to clean the air and no other technology comes close with respect to the results of a HEPA filter and you will not be introducing unwanted secondary pollution as is common with ozone generators, electronic, electrostatic and ionic purifiers.

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See how the HEPA air purifiers compare to the listing of top rated air purifiers.