What is a HEPA Filter in an Air Purifier – A Complete Guide to How it Works

What is a HEPA Filter in an Air Purifier

When buying an air purifier, you often have no idea what makes up the device’s internal parts. While it may be a tad difficult to understand the full functions of an air purifier, the devices’ inner workings shouldn’t be difficult to understand.

With this in mind, let us learn about what a HEPA filter is and how it works in air purifiers.

Also Read About: What is a Pre-Filter?

What Is A HEPA Filter in An Air Purifier?

The purpose of using an air purifier is to cleanse the air of these contaminants so you can breathe more easily without being exposed to any hazardous airborne particles.

Air purifiers usually have a HEPA filter installed to remove microscopic particles from the air, such as bacteria, viruses, mold spores, dust mites, and pet dander.

A HEPA filter is a special mechanical filtration system type. This filter removes particles from the air that may be harmful to your health. These filters are used in household and industrial settings.

How Does a HEPA Filter Work?

A HEPA filter catches air particles using static electricity and high-grade materials. Static charges cause particles to stick to the surface of the filter, as the denser material makes it harder for some types of particles (like dust or pollen) to pass through.

What is a HEPA Filter

These filters are often used by people with allergies, multi-pet households, or smokers. HEPA filters are made up of a metal wire mesh coated with millions of microscopic plastic fibers. These filter particles are as small as 0.3 microns in diameter, including pollen, smoke, and bacteria.

Types of HEPA Filters?

There are 3 main types of HEPA Filters, which are:

Is a HEPA filter better than a regular filter?

  1. HEPA Type or HEPA like
  2. True HEPA Filter
  3. Medical Grade HEPA Filter

1. HEPA Type or HEPA Like Filters

The HEPA type filter is usually cheaper but less efficient than the True HEPA filter. It only filters down to 85% of the particles, and this means that 15% or more can still pass through these filters because they do not capture all allergens and dust particles like a True HEPA Filter. So, HEPA Type or HEPA like Is not efficient at capturing all dust particles.

 2. True HEPA Filters

True HEPA filters are 99.97% efficient at capturing dust particles, allergens, and other contaminants. It means that only 3 out of every 1000 particles will pass through this filter. True HEPA Filter Capture, 99.97% of all the allergens.

3. Medical Grade HEPA Filters

Medicated HEPA Filters capture even more particles than True HEPA – 99.99%. The medical-grade HEPA filter is excellent for people who suffer from severe allergies due to the small number of particles that pass through this filter. 

Furthermore, HEPA filters can be either disposable or reusable. Disposable HEPA filters are most often found in air purifiers that use a pre-filter to capture large particles and then a HEPA filter to capture smaller ones. The pre-filter is usually made of foam or carbon and must be replaced periodically.

hepa filter types

Reusable HEPA filters are used in air purifiers that use a HEPA filter alone. These filters can be washed and reused for up to three years, depending on the air purifier model, though most users opt to replace them every six to 12 months.

Which Type of HEPA Filter is Best for You?

If you suffer from allergies or other health conditions, then a True HEPA filter can be the most effective at filtering out dust and other pollutants in your home. It reduces your exposure to irritating and harmful allergens and dust particles, triggering asthma attacks and other health problems.

A Medical-grade HEPA filter is perfect for allergy sufferers, as it can reduce the number of allergens that your air purifier emits into the air by up to 99.99%. It means that only 3 out of every 10,000 particles will pass through this unit.

Frequently Asked Questions

Do HEPA Filters Stop Coronavirus?

HEPA filters stop most the viruses, bacteria, and dust particles. It is not enough to remove everything that can enter you indoors, like coronavirus.

So, it is a good idea to have HEPA filters in your place because they can help you breathe better and protect yourself from inhaling harmful stuff.

Do HEPA filters stop coronavirus

Do HEPA filters Emit Ozone?

No, HEPA filters do not emit Ozone. Ozone is a colorless gas in the atmosphere and is a health hazard for humans. Ozone is formed when sunlight reacts with nitrogen oxides in the air, pollutants emitted by vehicles and power plants.

The reaction causes Nitrogen Oxide molecules to break down into smaller parts, eventually recombining to form ozone molecules.

Is a HEPA Filter Better Than a Regular Filter?

It all depends on your needs. Regular filters will remove larger particles, but they won’t catch as many bacteria as HEPA filters do. However, regular filters can be more affordable.

HEPA filters cost more than regular ones because they are designed to trap microscopic dust particles, mold spores, pollen, pet dander, and other allergens in the air. 


There is no denying that a HEPA air purifier and its filter work hard to provide you with clean, fresh-smelling air. High-efficiency particulate air filters use an electrostatic charge to trap tiny particles in your home, like dust and mold.

Furthermore, HEPA filters can be highly beneficial to people who suffer from asthma and allergies, as they trap airborne allergens and pollutants. 

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