Written by: Husna Sultana

Carbon air filtering is not a new technology and the usage dates to 1850’s, founded by John Stenhouse. NASA (National Aeronautics and Space Administration) uses the combination of HEPA and carbon filters to filter air inside of the space shuttle for astronauts.

How carbon filters help in removing odors, gases, and VOC’s

Activated carbon typically comes in granular or powdered form and consists of millions of tiny adsorbent pores. This air filter has been treated to be extremely porous, and this is the most popular and efficient filtration against odors, gases, chemicals, and Volatile Organic Compounds (VOCs).

The activated carbon is inserted into the air purifying device. Polluted air enters the filtration system, passes through the activated carbon, undergoes adsorption, and leaves the air purified and free of chemicals and VOC’s. If used in conjunction with a HEPA filter, the activated carbon works to prevent larger particles from reaching it, enabling the HEPA filter to perform better and last longer.

Difference between absorption and adsorption?

Absorption is what happens when a sponge sucks up water but is not bonded to the water at a molecular level.

Adsorption, on the other hand is a unique process where the pollutants stick to the surface of the activated carbon . The more porous the activated carbon is, the more contaminants it will capture. These filters are most notably used in home air purification systems to remove hazardous compounds.

What a HEPA filter cannot capture?

HEPA filters are very effective in removing pollen, mold spores, fungi, airborne particles with a size of 0.3 microns (µm), dust, pet dander, hair, and visible smoke. HEPA captures at least 99.97% of particles as small as 0.3 microns. It does not remove odors, atmospheric gases and chemical fumes or any VOCs.

Ailments caused by exposure to VOC’s and chemicals.

Acute/short term exposures
(hours to days)

Chronic exposures
(years to a lifetime)

  • Eye, nose & throat irritation
  • Headaches
  • Nausea/vomiting
  • Dizziness
  • Worsening of asthma symptoms
  • Cancer
  • Liver & kidney damage
  • Central nervous system damage


Important points to be considered while buying a Carbon filter.

The amount of activated carbon matters: The amount of activated carbon reflects the effectiveness of carbon air filters in removing odors, and the complexity (thickness) in carbon structures within the air filter itself has a big effect on the filter’s overall capability.

The thin and inexpensive carbon filters found on the market are ineffective at removing odors, chemicals, and pollutants from the air. Therefore, it is important to pick a filter which has higher carbon content (in weight) that is present in the air purifier.

Tests have shown that the higher the carbon content, better the air filtration. Airpura uses 18 - 26 lbs Carbon, regular or a special blend.

Carbon Pores:  The more porous the activated carbon is, the more contaminants it will capture.  Pores size can be micro (< 2 nm diameter), meso (2-50 nm diameter) and macro(> 50 nm diameter) depending upon how it is made.

Replacement of filters: When the carbon in the Carbon air filters become saturated or deteriorated by a rapid change in humidity or temperature, it may cause the filter to release the VOCs back in the air, this process is called as off-gassing. The carbon filters need to be replaced on a regular basis.

Different Blends of carbon: Airpura’ s Carbon filters have different blends (18lbs to 26lbs) depending upon the complexity of the VOCs and chemicals it filters.

The Best Air purifier for removing chemicals and VOC’s.

Airpura Air purifiers are designed to remove thousands of harmful chemicals and VOCs from your air with Airpura's custom blended activated carbon (the most amount in one purifier on the market!) They allow for optimized and augmented chemical abatement. They also come with a HEPA filter to ensure removal of pollen, micro-organisms, mold spores, fungi, dust, pet dander and hair or anything with a diameter of 0.3 microns and more.