Air filters are the first line of defense against pollution in your home; people generally think that breakdown occurs outside their homes. Meanwhile, they forget about the dust, suspended particles in the air, and dirt’s from outside. Air filters are like a medical mask, and they help remove particles from the air that can be dangerous to people. Different sources of indoor pollution are often ignored or taken for granted. A good example is the trash can, which produces an odor that can irritate the lungs and leads to allergies and asthma.


It is generally assumed that vacuuming removes dirt, but the real work is just rearranging the land. Don’t get it wrong. It does trap some ground but not all, and if you suffer from allergies or asthma, the air can be dangerous to your health.

Read more: Indoor Air Quality Drops in Winter (A Big Possibility)

There are different types of air filters, and selecting one depends on its application. Air filters have similar working mechanisms and functions no matter their application. All air filter is designed to clean air by passing them through a filter to remove particles like dust and dirt. It acts more like a sieve that filters that remove particles from the air as it flows through it, releasing only clean air into the room. The sieve traps particles that are greater than the hole, thereby preventing them from passing through.

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As more and more air is passed through the filter, it traps lots of particles, restricting the airflow. At first, this might be a good thing because the filter is full of particles, but it eventually blocks airflow. When this occurs, you may need to clean the filter or change it entirely, and if this is not done, the particles remain suspended in the air because no air is passing through the filter.

What is HEPA Air Filter, and How Does It Work?

Air filters are essential in removing dust particles. One such air filter is the HEPA air filter, which stands for “High-Efficiency Particulate Air” and describes a filter capable of eliminating or trapping 99.97 percent of particles about 0.3 microns. The creation of the HEPA air filter can be dated back to world war II. People used it to capture the dangerous particles released during the creation of the atomic bomb.

Now don’t get it mixed up. Most time, particles that are about 0.3 microns have been known to evade most filters. Although particles larger or smaller than 0.3micron get trap in the filter all the time, particles of this size can efficiently bypass most sieves.

There are different ways by which the HEPA uses to trap particles. For example, diffusion is very effective at trapping smaller particles. In comparison, larger particles are trapped through impact and interception, giving room for particles in the middle to scale through.

HEPA filters are made of interlaced glass fiber twisted and turned in a different direction creating a fibrous maze. As air is passed through the HEPA filter, particles become trap within the filter and allowing only clean air to pass through. The traditional HEPA air filter consists of micro-glass fiber.

It can also include a sub-micron, wet-laid glass, and a melt-blown polypropylene electrostatically charged fiber. The fiber is arranged in a non-woven pattern, which allows it to capture smaller particles effectively.

You may want to read more: Does an Air Conditioner Work as an Air Purifier?

4 Primary Ways That HEPA Filter Trap Particles

There are four primary ways by which the HEPA filter traps particles, and they are listed below.

  • Direct impaction

Large particles such as molds, individual dust particles, and pollen suspended in air travel in a straight path through the filter and collide with the glass fiber. This article sticks to the thread, and the only clean air passes through. In other words, they crash through the finer and are automatically absorbed by the fiber.

  • Interception

An interception occurs when contamination comes in close range to the fiber and gets stuck to it. Airflow continues in their path due to inertia and adheres to the side of the thread during airflow.

  • Diffusion

Minutes and ultrafine particles move randomly, unlike the large particles, and are more likely to hit the fiber and get stuck. In simple words, the random movement of contaminants and airflow causes them to crash into one another and filter thread, leading to their absorption by the glass fiber.

  • Sieving

Some particles are more significant than the gap between the fibers, thereby getting trapped as air flows through the air filter.

Types of HEPA Air Filter

HEPA air filters can be classified based on different factors:

  • The level of efficiency
  • How well they capture particles
  • Resistance to fire
  • The story of resistance to filter degradation
  • The Level of Efficiency

According to the American standard, HEPA air filter is classified using the minimum efficiency rating value (MERV), ranging from 1-18 on a scale range.

MERV 1-4 has an efficient below 20%. They don’t do much but can still remove dust particles and other contaminants. MERV 5-8 have an efficiency between 20%-35%, MERV 9-12 have an efficiency between 40%-75%, and are commonly used for residential appliances. MERV 13-18 has the highest efficiency rating of about 99.97%. They not only widely use this MERV range in the hospital but also use it for commercial and residential purposes.

  • Based on How Well They Capture Particles

HEPA air filters are classified using the letter A-E based on how well they capture particles. Type A is the least effective but can still meet the essential criteria for a HEPA air filter, while Type E is at the end of the scale and is the most effective. Type E is capable of trapping biological, chemical, and radiological particles.

  • Based on There Level Of Resistance to Fire

There are two types of filters under this classification, fire-resistant or semi-combustible filter.

  • Based on Their Level of Resistant to Degradation

There are three types of HEPA air filters based on this classification: lettered N, P, R.The type N is not resistant to oil, while type R is oil resistant, the type P is waterproof.

Maintenance Tips for HEPA Air Filters

  1. Ensure that areas around the air purifier are clean; accumulation of dust and particles leads to unnecessary work for the air purifier.
  2. Clean the micro-fiber cloths to remove dust effectively.
  3. Clean the grills and panels of the air purifier regularly.
  4. The air purifier should be placed in an open area rather than behind furniture, reducing its efficiency.
  5. Replace the HEPA filter every 3-4 months.

Final Words

In conclusion, this article answers the critical question about what a HEPA air filter is. Moreover, we also provide some more tips & guides on how it works and maintain the air filter’s quality. I hope that this article will be helpful to you. Please, if there is any question/ request, tell me in the comment section! Thanks for visiting!


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