What is a HEPA Air Purifier | How it Works

HEPA Air Purifier: What it is and How it Works

One of the most popular appliances in the market is the HEPA air purifier. Most households have this air purifier to address their allergy needs. It can remove airborne allergies like dust, pet dander, pollen, mold spores, dust mites that can trigger allergic reactions to susceptible people. More importantly, the common household pollutants and equally dangerous are the smoke particles, and volatile organic compounds, commonly known as VOCs, could also be removed by the air purifier.

Indeed! It works just like magic! Imagine air free from all these pollutants. You won’t have to worry about any respiratory allergies or cleaning the room now and then. What’s better with these air purifiers’ true HEPA filter units is that they can already capture bacteria and other microorganisms in the air, thus reducing their concentration and damaging your health.

So, if you’re planning to purchase one today or in the coming days to come, first know what a HEPA Air Purifier is. This is an in-depth explanation of what it is made of and how it does the air purifying. You should also know the benefits of helping you decide which is the best HEPA air purifier to buy! 

Before we continue to the guide, here are the top 5 best HEPA air purifiers:

TOP 5 Best HEPA Air Purifiers 2021

1. LEVOIT LV-H132 True HEPA Air PurifierLevoit LV-H132 True HEPA Air purifier for Home Smokers Allergies and Pets Hair

Not only one of the best but also most loved and popular HEPA air purifiers, the Levoit LV-H132 is one that can fight against any air issue you may be experiencing at home. It makes sure that you breathe clean air. Anything that is not air will be cleaned out. It highlights an activated carbon filter, a HEPA filter, and a Preliminary filter. Three of them manage the air-purifying job perfectly. The air filters last for over six months so that maintenance won’t be that costly.


  • Powerful performance
  • Awesome price/performance ratio
  • Small, space-saving device


  • No light notification on filter replacement
  • No auto shut-off feature

2. Germ Guardian AC4825 True HEPA Filter Air PurifierGerm Guardian AC4825 True HEPA Filter Air Purifier

The Germ Guardian AC4825 3 in 1 True HEPA air purifier with UV Sanitizer and odor reduction is the number one bestseller and the quietest bedroom air purifier. This air purifier is one of the best in the price range under $100. The Germ Guardian AC4825 Air Cleaner is ideal for small to medium spaces and has a recommended room size of 155 square feet (14m2).


  • Best price/performance ratio
  • True-HEPA filter
  • Great value
  • 3-year warranty


  • Noisy on the highest speed

3. Coway AP-1512HH Mighty Air Purifier with True HEPACoway AP-1512HH Mighty Air Purifier with True HEPA and Eco Mode

Coway AP-1512 Air Purifier is beautiful with a unique design. This compact air purifier holds high-quality filtration, awesome features – air quality sensor, filter replace indicator, auto mode, timer, and enough to purify large spaces up to 326 square feet. On lowest setting uses only 7W power.


  • Perfect for small rooms
  • Affordable
  • Practical


  • Not for very large rooms

4. Winix WAC5500 HEPA Air PurifierWinix WAC5500 True HEPA Air purifier

The Winix WAC5500 is a great air cleaner for rooms up to 350 square feet (32.5m2). Best price for such size space. The Winix WAC5500 contains a 99.97% efficient True-HEPA Filter, Odor Control Carbon Pre-Filters, and PlasmaWave Technology.


  • Improved technology
  • Well made for the price
  • Excellent overall performance


  • Some still claim that PlasmaWave irritate asthma

5. Rabbit Air MinusA2 Ultra Quiet HEPA Air PurifierRabbit Air MinusA2 Ultra Quiet HEPA Air Purifier - Stylish, Efficient and Energy Star (SPA-700A, White, Odor Remover)

It runs with HEPA – one of the most trusted and advanced filtration technology in the world. Customizable filtration – can choose between various filter sets depending on your needs. Covers up to 700 sq. ft. spaces, incredibly low noise level, low Power Consumption. Five-year warranty.


  • Perfect True HEPA filter
  • One of the advanced filtration process between all Air Purifiers
  • Unique design with several design options
  • It’s possible to mount on the wall


  • No operational timer

What does HEPA mean?

Most of the best selling air purifiers online are HEPA air purifiers. We commonly see the term “HEPA” tagged along with the model name of different brands. HEPA stands for High-Efficiency Particulate Air. It is a type of air filter used in several systems that need clean air like vehicles, home filters, hospitals, and airplanes. It is not merely put in a unit’s name; it is a qualifying product status. The filter to be labeled as HEPA has to pass certain standards set by the Department of Energy.

How does a unit qualify as a HEPA air purifier?

Indeed, buying a HEPA air purifier is not just a small deal because it should pass government standards for a filter unit to have a HEPA label. A filter must be able to remove 99.97% of all particles from 0.3 micrometers up. However, being Hepa qualified does not necessarily mean the highest standards. It’s just one of the classifications of air purifiers. These will be further sorted according to their filter capacity.

How small are 0.3 micrometers?

A micrometer or commonly known as a micron is very small! It is equal to 1 millionth of a meter. Particles this small cannot be seen by the naked eye. This is very important to point out for HEPA filters because most allergens are of this size. They are tough to capture or filter, and if they pass through the respiratory system, they may cause coughing, sneezing, and runny nose.

These are the common air contaminants we can see in the house, along with their sizes. Human hair (70-100 microns), pet dander (0.5-100 microns), Pollen (5-100 microns), Mold (2-20 microns), Plant Spores (6-100 microns), smoke (0.01-1 micron), dust mites (0.05-50 microns), bacteria (0.35-10 microns).

How does it work?

HEPA Air purifier How it works

HEPA filters are made of a mat of randomly arranged fibers. These are commonly made of fiberglass, the size of 0.5 to 2.0 micrometers. The important detail is the distance between one fiber to another. Particles are trapped in the mat of fibers through the following simple processes.

Interception: Particles usually follow a single pathway by an air stream produced by your air purifier.

Impaction: As the air stream continues to flow in and out of the machine, larger particles cannot surpass fibers; therefore, they are attached to one of the fibers. This is commonly coined as capturing the particles by forcing them into sticking into the fibers.

Diffusion: Molecules in the air collide with smaller gas molecules; therefore, their motions are stopped.

Can HEPA air purifiers really kill viruses and bacteria?

HEPA Filters cannot only capture inanimate objects but living microorganisms as well. Once they are captured, these bacteria and viruses may die. The HEPA filter is a dry environment and is not an ideal moist medium for bacterial growth. Yes, these microorganisms can be killed. However, if the air coming into the filter is moist, bacteria can grow.


Indeed HEPA air purifiers can do well in cleaning the air from common household allergens. Now, let’s see the benefits of having a HEPA air purifier at home.

If you are exposed to air pollution, this may cause several health issues like allergies and respiratory infections. Little did we know that the air inside our house is equally polluted as they’re on the outside. Breathing air with many pollutants can cause aggravation of present conditions. Respiratory or not, inflammation can happen because of these particles. You should have an air purifier if you have one of these persons:

  • If you’re concerned about having the healthiest home possible.
  • If you want a pet but are afraid of the allergies pet dander may cause.
  • If you already have asthma and allergies with many recurrent attacks.
  • If you want to remove smoke odors and other common household odors that have long been lurking in your homes.
  • Found yourself in any of these situations? You should really think about buying one.


However, there are some customer concerns about having a HEPA air purifier. Some of the machines have gaseous by-products that can be hazardous to your health. Also, most customers complain about the level of noise, the frequency, and the expense of changing the filters, electrical energy consumption, and visual appeal.

To resolve these possible concerns, you can read well customer reviews regarding the product you will buy. You can also call the company’s customer service to know the noise level (in decibels), for example, to prepare you for what to expect in a product. Several HEPA filter purifiers can last 3-5 years; some are even permanent. What’s important is that you clean your units regularly.

My name is Ryan. I have had a hard time dealing with my allergies. Happily, I found that an air purifier was effective to ease my allergy symptoms. I spent a lot of time researching the best air purifier. I know how hard it can be to find the suitable one. During the reading period, I also read a lot about humidifiers and dehumidifiers. I learned the mechanisms behind the technologies as well as the manufacturers and organizations within the industry. I now feel convinced that I have built a guide that shows you all you need to know about air purifiers, humidifiers, and dehumidifiers. So I came up with the idea of creating this website.

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