The pre-filter traps larger dust and particles. It may be vacuumed from the exterior of the unit. It acts to stop the larger particles such as dust and lint from clogging the other filters.

The activated carbon bed adsorbs airborne chemicals, gases and odors. Many air purifiers offer only a spray of carbon sprayed on the pre-filter. This is only sufficient to capture a small amount of gases and odors and soon fills up.

Airpura carbon filters have from 18 to 30 pounds of activated carbon that will trap 60% of its own weight in airborne chemicals, gases and odors. They will keep on adsorbing harmful chemicals for 24 months in typical use.

The 2 Micro-supress filters on each side of the carbon bed kill microbes that may collect on them.

The true HEPA filter traps airborne particles. These filters were developed by the Atomic Energy Commission to trap radio-active particles. They can capture 99.97% of particles as small as 0.3 microns. That is as small as some bacteria.

Adsorbtion with Activated Carbon

Activated Carbon is the only safe, cost effective way to trap noxious gases and odors

Activated carbon has been treated with oxygen to open up millions of tiny pores between the carbon atoms.

There are so many of these spores that one pound of activated carbon has a surface area of 60 to 150 acres.

Activated carbon is the substance that keeps military personnel safe from poisonous gases. It is also used for water filtration.

Adsorbtion is the process where certain chemicals are attracted to activated carbon and then bond to it. The millions of pores in the activated carbon provide an enormous surface area to trap these chemicals.

The bigger the filter, the more chemicals it adsorbs and the longer it keeps on working

An activated carbon filter acts rather like a sponge. When it is full it can adsorb no more. The more carbon you have the more you can adsorb before changing the filter.