With the increasing awareness of the effects of pollution and the concern over the spread of germs, consumers are considering different air purifiers to help reduce their exposure. When determining the best air purifier, you may need to consider PM2.5 vs. HEPA filter and how effective a HEPA filter is.


  • Particulate matter that is 2.5 micrometers or smaller is referred to as PM2.5.
  • HEPA filters eliminate 99.97% of particulate matter that is 0.3 microns in size or larger.
  • When it comes to PM2.5, HEPA filters in air purifiers help reduce the concentration, resulting in fewer health issues.

HEPA Filters vs. PM2.5 Effectiveness

Brands install high-efficiency particulate air (HEPA) filters in their air purifiers with the idea of improving indoor air quality in mind. According to the U.S. Department of Energy, each filter receives testing at an independent air filter test facility. These filters eliminate 99.97% of larger particles that are 0.3 microns in size or larger. HEPA air purifiers can last for years but need to be maintained over time so they perform optimally, like for example, users may want to learn how to reset their HEPA air purifier for when the time comes. Additionally, these filters have been shown to reduce PM2.5 concentrations by 50%. For more comparisons with HEPA filters, check out our guide to plasma air purifiers vs. HEPA filters or our comparison of a HEPA filter vs an air purifier.

Insider Tip

HEPA filters in air purifiers could help to reduce some PM2.5.

What Does PM2.5 Mean?

PM stands for particulate matter, so PM2.5 (sometimes written as PM2.5) refers to particulate matter 2.5 micrometers or smaller. This size is roughly 3% of the diameter of a single strand of human hair. The EPA and several other organizations consider these microscopic particles to be fine inhalable particles. People are exposed to these particles through both indoor and outdoor air pollution, and PM2.5 poses the most significant risk. If you are curious to learn more, check out our article on how a PM2.5 air purifier works.

How is PM2.5 Harmful?

PM2.5 particles may get into your lungs and heart. People with cardiovascular disease or lung disease may suffer the most due to these common particles. However, others may experience nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function, and other respiratory issues. Hazardous levels may also impair vision, such as when haze occurs in parts of the U.S. If you need a hospital-grade air filter in your device, you can also get an H13 air filter. If you’re wondering what is a H13 HEPA filter, we explain it further in this linked guide.

Do HEPA Filters Remove PM2.5?

In one study, a HEPA air purifier with pre-filters was placed in two rooms within the non-smoking homes of 71 children with asthma. The household’s PM2.5 was measured at baseline and again at one year. In the experimental group of 36 families, the researchers saw significantly smaller concentrations of PM2.5 at the one-year follow-up. In addition, these high-efficiency mechanical filters reduced the indoor PM concentrations by 60%. Something else to consider is if a room or whole-house air purifier is better and more effective. While HEPA filters have been shown to help improve allergy symptoms, if you have severe allergies, you may want to check out our comparison of a HEPA filter vs an allergen filter to see which will be most beneficial. Additionally, check out our page on why buy an air purifier that’s energy efficient, so you aren’t wasting money while cleaning your air.

If you can’t afford an air cleaner, you’ll want to know how to make an air purifier from scratch for less than $40.

HEPA and Activated Carbon Air Purifiers

When researchers placed an air purifier with HEPA and activated carbon filters in 43 households with children with asthma, the air purifiers significantly reduced the number of pollutants and airborne particles indoors. That’s why it’s a good idea to know how to buy an air purifier, so you get the right one. In addition, homes with less outside air came in saw more of an improvement than those with dust mites and gaseous pollutants from outside sources. However, results varied between homes, and thus individual exposure reduction strategies were recommended.

What is an Activated Carbon Filter for Air Purifiers?

An activated carbon filter eliminates gaseous pollutants and organic compounds from the air. In addition, this product will eliminate odors from the air in your house or office. When removing toxins in the air, the activated carbon catches more than a fabric air filter. However, on their own, these filters do not trap as many particles. Combined with HEPA filters, the two can eliminate both gaseous and airborne pollutants. For more info, check out our match-ups of HEPA filters vs air purifiers, and water air purifiers vs filters.


PM2.5 can be found indoors and outdoors as a result of air pollution.


Can air purifiers with HEPA filters remove COVID-19 and other viruses?

Air purifiers may reduce exposure to COVID-19 and its variants, but they cannot eliminate the viruses. HEPA filters remove particles 0.3 microns in size or larger, which does not include all COVID-19 particles.

What is the reduction of PM2.5 with a HEPA filter?

HEPA filters have been proven to eliminate on average 50% of PM2.5, though the exact amount varies by device. Appliances with multiple filtration methods may enhance this process.

Do HEPA Air Purifiers Remove PM2.5?

HEPA air purifiers remove some of the particles that fall under the category of PM2.5. However, they cannot eliminate all of these pollutants.

STAT: The size of PM2.5 particles is roughly 3 percent of the diameter of a piece of human hair. (phys.org) (source)

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