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The main task of an air purifier is to clean the pollutants from the environment so that you can breathe in a fresh atmosphere. Unless the air is clean, there are chances that you are going to suffer from different kinds of diseases. For a healthy life, it is imperative that the air is clean, and air purifiers can help greatly in this regard. Although every air purifier serves almost the same task, the one that is considered the best among them is the air purifier that consists of a true HEPA filter. This can be the perfect filter for so many reasons.


The word HEPA stands for high-efficiency particulate air. The best thing about a HEPA filter is that it can remove up to 99.97% of microscopic pollutants in the environment. This is entirely true. For all the people who are a clean freak and who want to make sure that there is not even a single particle of dust that should go for this filter. Even the tiniest of dust particles are unable to survive in its presence. It can even remove dust particles that are as small as 0.3 microns in size.

From atmospheric dust to cement dust, from bacteria to dust mites, from insecticide dust to mold holes, it can destroy all sorts of harmful microscopic particles present in the environment. If there is one thing that can guarantee the cleanest air in your room, it is this filter. Generally, a HEPA Filter that can surely clean the air up to 99.97% is called True HEPA Filter.

What is it made of?

A true HEPA filter is composed of a highly dense paper made of thin fibers. The distance between them is between 0.3 and 2.0 microns. These fiber glasses have a very high density and have the ability to stop the smallest particles from passing through.

What is HEPA Type Filters?

It is another HEPA filter, but it is not as efficient as the True HEPA filter. People buy it because it does not cost much. In an era where filters can be damn expensive, this one is economical. For this reason, it is high in demand, and people buy this like hotcakes. It made of the same stuff that the true HEPA filter made of, but the density between its glass fibers is not very high. It is called the HEPA type filter.

Difference between the True HEPA Filter and HEPA Type Filter

One of the most significant differences between a true HEPA filter and HEPA type filter is their efficiency. Hepa type filters can capture about 90- 99% of dust particles, but a true HEPA filter can remove up to 99.97% of microscopic pollutants. Also, the HEPA type filter can only capture particles of 2 microns in size, but a true HEPA filter can capture the particles of 0.3 microns in size. If you are one such person who likes the efficiency of filters, then a true HEPA filter is your answer.

On the other hand, if you need a filter for temporary usage, then you can go for Hepa Type Filter.

How does a true HEPA Filter Work by using a Combination of three Physical Mechanisms?

A true HEPA filter can capture particles of such small size only because of the smart design and the combination of three mechanisms that it uses. The mechanisms are as follows:

Inertial impact

True HEPA Filters

The inertial impaction mechanism of a true HEPA filter is used to capture the large particles. The fibers in the true HEPA filters are distributed randomly because the heavier particles are unable to follow the gas flow streamline. Because of the large size inertia, they are captured by these HEPA filters.


What are true HEPA filters

The interception mechanism is used to capture the particles that are not so large. They are captured by the edge of the fibers because these particles are larger than the distance between the edge of the fiber and the streamline. In this process, these particles do not collide with the help of filters in a direct manner but died later captured by the edge of the fibers.


True HEPA Filters

Furthermore, there is another mechanism that is considered to be the most important mechanism used by HEPA filters. With the help of diffusion, the HEPA filters can get rid of the smallest particles. These particles, which are as small as 0.3 microns, are unable to follow the streamline. Due to their smaller size, they collide randomly with the gas molecules. Because of the high freedom of movement they encountered the fiber because of continuous collision with the gas molecules. In this way, they are captured by the HEPA filters.

The true HEPA filters are so efficient because of the three filtration mechanisms it uses. Had there been no such mechanisms there were chances that this filter wasn’t the talk of the town but things are in favor of this filter because of the mechanisms.

The above illustrations are taken from the a good resource to understand the basics of air filtration by Jerry Sipes, Ph.D., P.E.

Are all HEPA filters the same?

Not all HEPA filters are the same. Different air purifier brands use different techniques. They differ in the density of the fibers and the materials that are used in constructing them. Some air purifier brands use technology that enhances the efficiency by the ionizer, other brands have invented the sort of HEPA air filters that are made of nano-fibers and can capture particles of about 0.003 microns. It mostly depends upon the brands and on the usage.

MERV Rating and the Efficiency of HEPA Filters

MERV stands for minimum efficiency reporting value. This rating explains the efficiency of various filters to remove those particles. The filters that have high ratings can capture to remove car fumes and even microorganisms. It is important to follow the mermaid rating in choosing a filter for your home because it ensures the safety of your loved ones. The higher the rating, the better the filters.

Are HEPA Filters Washable?

HEPA Filters are washable but only when they are written on their labels. If the washable characteristic is not written on the label then you have to be very careful. There are various ways of washing HEPA filters. You can wash it with water. It is recommended to use lukewarm water in this regard. The addition of lukewarm will clean these filters in a much better way. Also if your filter is nonwashable then you can use a vacuum cleaner to clean the dust from your filter.

Pros and Cons of True HEPA Filters

Every filter comes with a list of pros and cons. The best thing about HEPA filters is that they have more pros and cons.


  • Able to capture even the tiniest particles. It doesn’t matter how stubborn the particles are, with this filter they are going to be dead.
  • Trapped particles will not be released into the air. Instead, they will stay within the filter and you can wash them with water or a vacuum cleaner. This alone will make this filter the perfect choice for your home.
  • They are not the emitters of ozone which makes them the best of all the filters.


  • They cannot remove smells. However, they can remove particles of up to 0.3 microns, yet they are unable to remove smells and odors. The smell may never leave your room.
  • They need your constant attention and require filter replacement on a routine basis for efficiency.

Final Thoughts

Out of all the filters, HEPA filters are the best because they do not release the life-threatening ozone into the air. Also, they capture the particles of even the smallest size and prevent them from destroying your lungs or respiratory system. In short, apart from some little cons, they are flawless. If you need to save yourself or your loved ones from airborne germs and diseases, then the true HEPA filter is the answer. Nothing can be better than this filter for your space.

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