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Particle Sizes – What is Your HEPA Filter Catching and Missing?

In recent years, HEPA filters have become increasingly popular as a means of purifying indoor air. These filters are known for their ability to remove even the smallest particles from the air, making them an excellent choice for people who suffer from allergies or respiratory problems. In this blog post, we will explore the different particle sizes that a HEPA filter can catch, the ones that it can’t catch, and some alternative air purification methods.

What is a HEPA Filter?

HEPA stands for High-Efficiency Particulate Air. A HEPA filter is a type of Particle Sizesair filter that is designed to remove particles from the air. These filters are made of dense, tightly woven materials that trap even the tiniest particles. The filter is designed to be very efficient, removing 99.97% of all particles that are 0.3 microns or larger.

What Particle Sizes Can a HEPA Filter Catch?

Particles are measured in microns and categorized by size. HEPA filters are designed to catch particles that are 0.3 microns or larger. This includes things like dust, pollen, pet dander, and mold spores. In addition to these common allergens, HEPA filters are also effective at removing smaller particles, such as bacteria and viruses. These particles can be as small as 0.01 microns, which is much smaller than the 0.3-micron threshold that HEPA filters are designed to catch. However, due to the way that HEPA filters are designed, they are still able to capture these tiny particles. Types of particles that your HEPA filter should catch include:

  • Pollen: 10-100 microns 
  • Pet dander: 0.5-100 microns 
  • Dust: 0.5-100 microns 
  • Fungal spores: 2-100 microns 
  • Tree and grass pollen: 20-30 microns 
  • Ragweed pollen: 10-20 microns 
  • Mold spores: 2-20 microns 
  • Bacteria: 0.5-5 microns 
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What Particle Sizes Can’t a HEPA Filter Catch?

While HEPA filters are effective at removing a wide range of particles from the air, there are some that they can’t catch. These include gases, odors, and chemicals. HEPA filters are not designed to remove these types of pollutants from the air, so if you are concerned about these types of pollutants, you may want to consider using a different type of air purifier. Depending on the size, types of particles a HEPA filter may miss include:

  • Lead particles: 0.1-10 microns 
  • Combustion particles: 0.1-1 microns 
  • Smoke: 0.01-1 microns 
  • Viruses: 0.02-0.3 microns 

Alternative Air Purification Methods

If you are looking for an air purification method that can remove gases, odors, and chemicals from the air, there are several options available. One of the most popular is activated carbon. Activated carbon is a type of material that is designed to absorb gases and odors from the air. It works by attracting and trapping the particles on its surface, which prevents them from circulating in the air.

Another option is electrostatic precipitators. These air purifiers use an electrical charge to attract and trap particles in the air. They are particularly effective at removing particles that are too small for a HEPA filter to catch, such as tobacco smoke and cooking fumes.

UV-C light air purifiers are also gaining popularity. These air purifiers use ultraviolet light to kill bacteria and viruses in the air. They are particularly effective in small spaces, such as bathrooms and bedrooms.

Photocatalytic oxidation or PCO, the same as in a car converter, is another method for purifying air. PCO works by having UV-C light shine onto a surface, which acts as a catalyst, and converts harmful airborne chemicals, also known as Volatile Organic Compounds (VOCs), into harmless water and carbon dioxide molecules.

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Any of the Field Controls portable air purifiers, including the TRIO Portable, TRIO Plus, and TRIO Pro, all combine a HEPA filter, UV-C lamps, and PCO in one portable unit for the ultimate option for protection.


HEPA filters are an excellent choice for people who want to remove common allergens and pollutants from the air. They are designed to remove particles as small as 0.3 microns, making them effective at capturing dust, pollen, pet dander, and mold spores. However, HEPA filters are not effective at removing gases, odors, certain viruses, and chemicals from the air. If you are concerned about these types of pollutants, for example, you have allergies triggered by cigarette smoke or you are immunocompromised and need additional protection from airborne viruses, you may want to consider using an alternative air purification method. Those include activated carbon, electrostatic precipitators, PCO, or UV-C light air purifiers. By choosing the right air purification method for your needs, you can enjoy clean, healthy air in your home or office.

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