Air Purifier Comparisons

Air purifier comparisons based on performance can best be done with the mechanical filters, of which HEPA based air cleaners are an example.

The performance comparisons between different mechanical air purifiers is based on the efficiency to clean certain size particles and on volume flow rate of air treated.

Perhaps the most used performance measure of the mechanical filters is how effective the air purifier is on cleaning particles of size 0.3 microns in diameter and larger.

According to American Lung Association, particles of 0.3 microns in diameter represent the respirable size most likely to reach and be deposited in the alveoli of the lungs - they are also the most difficult to remove by mechanical filtration. Both larger and smaller particles are captured with greater efficiency.

Air Purifier Comparisons - HEPA, ULPA, and SULPA

Three of the most commonly featured technologies that have high performance ratings on capturing particles of the size 0.3 microns are HEPA (High Efficiency Particulate Air), ULPA (Ultra Low Penetrating Air), and SULPA (Super Ultra Low Penetrating Air).

Of these, HEPA filters have an efficiency rate from 99% to 99.97% of particles removed of the size 0.3 microns or larger of treated air.

The specification was reportedly designed by the Atomic Energy Commission during WWII. The original purpose was to classify efficiency as to how efficiently radioactive plant exhausts were retained by the filter.

The same type of classification may be found as an S-Class filter specification.

ULPA specifies filters used in pharmaceutical labs and similar types of environments where the highest degree of clean air must be maintained. An ULPA filter must collect particles to 0.12 µm in size with efficiency of 99.999%.

Finally, SULPA filters take ULPA one level further, and they're available where maximum cleanliness is required.

These filters have an efficiency of 99.9999% on the same basis as ULPA filters.