Understanding How Air Filtration Works

Air filtration is essential in reducing the amount of polluting particles from the air. The system is commonly present in almost any HVAC system, including air conditioners, air purifiers, and even vacuum cleaners. But what makes it possible for  this simple technology to be so impactful and beneficial?

The Differences Between Air Filtration and Air Purifying

Many people mistake air filtration with air purifying. Although the concepts are similar, the two terms refer to different things. Air filtration is a device that captures particulates from the air using a fiber panel. Meanwhile, an air purifier is a system designed to reduce the pollutants contained in the air.

There are various technologies used for air purifying, including air filters. Compared to other air sanitizing systems, air filtration is the most commonly used for air purifiers.

How Air Filtration Works

Air filtration is installed inside a machine. The machine, will push the air through the filter. Since the air filter is porous, the air will pass through it while the particles get stuck inside the device.

The most common particles  polluting the air are the ones  between 0.3 to 10 micron, which is classified into three size ranges :

  • E1 : 0.3 to 1.0 microns
  • E2 : 1.0 to 3.0 microns
  • E3 : 3.0 to 10 microns

Density and Efficiency

The porous densities of various air filters differ. Needless to say, the denser the fibers, the more pollutants it can capture. To measure the filter’s capability, there is a tool called a MERV rating. Short for Minimum Efficiency Reporting Values, MERV classifies air filters by their ability in capturing particles. MERV ratings are range from 1 to 16.

  • MERV 1-4:  captures <20% of E3 particles. It is usually found in affordable split AC units.
  • MERV 5-8: can capture >20-70% of E3 particles and >0-20% of E2 particles, including most common dust, pollen, and mold.
  • MERV 9-12: captures >75-90% of E3 particles, >35-80 of E2 particles, and >0-35% E1 particles.  
  • MERV 13-16: captures >90% of E3 particles such as viruses and bacteria. A great option for anyone with a compromised immune system or severe allergies.

Most households and commercial buildings use filters in MERV 5-8 because those are enough to cover basic requirements. The 9-12 ones are common for fancy residentials and  commercial establishments. Meanwhile, those of MERV 13-16 are usually for hospitals, smoking lounges, and common households with severe allergens in them.


The most efficient air filtration is the ULPA (Ultra-Low Particulate Air) filter with up to 99.9995% efficiency in capturing particles as small as 0.12 microns. However, this filter is  rare. On the other hand, HEPA (High-Efficiency Particulate Air) filters are  more widely available. With up to 99.99% efficiency, these  capture particles as small as 0.3 microns.

As the environmental crisis gets worse, the particulate matter in the air is getting higher as well. Therefore,  air filtration systems are becoming more crucial.   It is necessary to understand how the system works so you can get the best one at a price you can afford for your HVAC appliance.  

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