You have probably heard of this commonly used acronym and effective way to purify indoor air, but you may also be wondering: What exactly is a HEPA filter?

HEPA stands for high efficiency particulate air, and it’s a way of categorizing the quality of air filters built to remove dust, pollen, pet dander, mold, bacteria, and other airborne particles from indoor air.

A filter of HEPA quality used within heating, ventilation, and air conditioning (HVAC) systems can greatly improve the quality of indoor air by filtering out some of the particles that can be of the greatest health concern.

There are many options on the market, and understanding the ins and outs of the various air filters can be tricky. We focused on HEPA air filters that could be used for a whole house or HVAC system.

Take for example MERV, another air filter rating system that stands for minimum efficiency reporting value. A MERV 13 or higher is recommended, but a HEPA traps even smaller particles and is estimated to be the equivalent of MERV 17.

Therefore, for the purpose of this roundup, we will only focus on HEPA-rated air filters, to ensure the highest possible efficiency. We also used the following criteria for selection:

  • Nonozone producing: In some air filtration systems, ozone can be introduced into the indoor air at “significantly above levels thought harmful to human health,” according to the Environmental Protection Agency (EPA).
  • Nonionizing: In addition to the concerns about ozone production, ionizing air purifiers aren’t deemed by the EPA to be as effective. “They do not remove gasses or odors, and may be relatively ineffective in removing large particles such as pollen and house dust allergens,” according to EPA.
  • Customer reviews: We only opted for products with 4.5 stars or higher and at least 500 reviews.

Pricing guide

HEPA filters should not necessarily cost a lot. We aimed to balance price point with the longevity of the filter, and used the following pricing guide:

  • $ = under $150
  • $$ = $150–$250
  • $$$ = over $250

To help create our list of top picks, we talked with Jake Loiko, owner of Hawks Mountain Home and Property Services in Springfield, Vermont. Loiko suggests first ensuring your HVAC system has a filter. “If you don’t have a filter, contact your local HVAC company and have them install a filter rack,” he says.

Key questions to ask when deciding on a filter, says Loiko, is the size filter you need and what you want to filter out. That’s why most of the filters in this list are categorized by what kind of pollutants they filter out.

Best overall air filter

  • Price: $$

The Coway Airmega is all around the best bang for your buck. It’s designed to accommodate rooms up to 361 square feet, so it works well for bedrooms and living rooms. It also features a communication sensor, so you get an up to date reading on your indoor air quality.

This air filter is designed to operate quietly, so you can keep it running without being disturbed. Priced at $230, it’s a high quality filter at a relatively affordable price. Note: There’s an ionizer in this machine, but it features an on-and-off button so you have the option of turning it off.

Best air filter for pets

  • Price: $

Pets can help make a house a home, but they can also introduce pet dander and odors. The Bissell MYair Pro helps to trap allergens and dander with its HEPA filtration system and a carbon filter captures odors. It filters 266 square feet with two air changes per hour. As a bonus, every purchase supports the Bissell Pet Foundation, which saves homeless pets.

Quietest air filter

  • Price: $$

This is billed as a bedroom air purifier because it cleans a 388-square-foot medium room in about 12.5 minutes, at decibel levels of 23 and below — that’s quieter than a whisper. It’s considered a more energy efficient model, and comes in several attractive colors. It also has a carbon filter to trap light household odors too.

Most high tech air purifier

  • Price: $$

This air purifier covers a large area and is able to purify 403 square feet up to five times in an hour. It uses three-stage filtration to trap viruses, bacteria, pollen, dust, and pet dander and an activated carbon filter to neutralize odors and smoke.

What also sets it apart from other purifiers are some of its tech features, such as hands-free voice commands that can connect to your Amazon Alexa or Google Assistant. You can also schedule settings for various times in the week in advance.

Best air purifier for large spaces

  • Price: $$$

This is the most expensive air purifier on the list, but it’s comparable in price to other air purifiers that can also tackle large spaces. This is designed to purify a much larger area and is able to deliver clean air to rooms of 540 square feet in about 12.5 minutes, or up to 2,592 square feet of space in 60 minutes. It also does this while managing to stay under 31 decibels.

Most economical air purifier

  • Price: $

At just under $70, it’s no surprise that this HEPA air purifier had 4.5 stars and over 16,000 ratings. It’s best suited for small rooms, however, using dual-channel and 360-degree air inlets technology to refresh the air in rooms up to 215 square feet. It operate quietly too — under 22 decibels — and has an aroma pad for essential oils.

Product namePriceCategoryCoverage area
Coway Airmega AP-1512HH(W) True HEPA Purifier$$Best overall air filter361 square feet
BISSELL MYair Pro Air Purifier with HEPA Filter for Small Room and Home$Best air filter for pets266 square feet
BLUEAIR Blue 311 Auto Bedroom Air Purifier$$Quietest air filter388 square feet
LEVOIT Core 400S Smart True HEPA Air Purifier$$Most high tech air purifier403 square feet
BLUEAIR Blue 211+ Air Purifier Large Room$$$Best air purifier for large spaces2,592 square feet
AROEVE MK01 Air Purifiers for Home$Most economical air purifier215 square feet

Air filters work by trapping pollutants in the fibers of their paper-like material. A HEPA grade filter can, theoretically, trap particles as small as 0.3 microns (for reference a human hair may be between 17 and 180 microns in width). That means that when placed in a filtration system, HEPA filters can remove 99.97% of particles from the air.

Visit local home improvement stores

Your local hardware store will have most of your basic filters, and can be a good place to compare prices and see your options firsthand.

Have the HVAC system checked

Loiko’s biggest tip for homeowners is to make sure that your HVAC system is well maintained.

“If your heating system is not taped at every seam when it’s sucking in the air, that means it’s drawing air from everywhere in your house,” he says. “So if that’s not all coming through the filter, you can put the most efficient filter on in the world and it won’t mean anything.”

That’s why he recommends a professional deep-cleaning service to clean ducts and tape any areas that are not sealed up properly.

All air filters require cleaning or replacement to work as promised. “You don’t need a professional to do it,” Loiko says. “Just find your filter, pop the housing off, and swap the filter out.”

How often to clean or replace the filter will depend on the season or region, but Loiko recommends a minimum of every 3 months.

“If you’re living in a highly forested area, your pollen season is going to be wicked, and you may need to replace it more often,” he says. And keep in mind that the higher the efficiency, the more often you will have to clean or replace it, Loiko says.

Though HEPA filters are a highly effective way to clean the air, there are other types of filters, including electrostatic filters and electrostatic precipitators, that use a small charge to trap particles.

There’s also ionization, a process that charges the particles in a room so that they’re attracted to walls, floors, tabletops. Some devices using ionization can attract the charged particles back into the unit. Ionization isn’t recommended by the EPA, especially for people with respiratory diseases, as potentially irritating ozone can be released in the ionization process.

Newer filtering systems use ultraviolet (UV) irradiation light to kill germs, Loiko notes.

“A lot of systems are going UV now,” he says. “It’s not just a filter, it kills bacteria, and that’s why those are becoming hugely popular.”

Keep in mind, says Loiko, that UV filters would need to be used in tandem with an air filter that takes care of the particles themselves. “If you’ve got cat hair flying around, UV’s not going to take care of that,” he says.

Do HEPA air filters actually work?

According to the EPA, HEPA air purifiers can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns. In practice, studies suggest that air purifiers are effective mitigation measures for controlling indoor particulate pollution.

They can be employed in indoor environments to trap airborne allergens bacteria, viruses, and smoke. The scientific research warns that the type of air filter is paramount to its effectiveness, which is why HEPA remains the gold standard.

Are there disadvantages from using HEPA filters?

HEPA air filters cannot trap particles smaller than 0.3 microns, which can include fine dust, some bacteria and viruses, asbestos, and fungal spores. In addition, filters must be changed regularly in order to be effective, adding to the cost of this investment.

Old filters can even make matters worse, as pollen and allergens can become trapped in the filter and degrade air quality.

Buyers must also beware of air purifiers that use ionization or introduce ozone into the air, which can be harmful to your health.

Do HEPA air filters help with the flu or COVID-19?

Studies have shown that HEPA air filters may be effective in clearing the air from airborne transmission of viruses, such as the flu or COVID-19. However, there’s no concrete way to measure the effectiveness. That’s why the EPA and other scientific literature is reluctant to quantify the ability of an air purifier to help with flu or COVID-19.

Here’s what the EPA says about air purifiers for COVID-19: “By itself, air cleaning or filtration is not enough to protect people from COVID-19. When used along with other best practices recommended by CDC and other public health agencies, including social distancing and mask wearing, filtration can be part of a plan to reduce the potential for airborne transmission of COVID-19 indoors.”

Though no HEPA filter will remove all the indoor air pollutants, a high efficiency filter, combined with a well maintained HVAC system, can go a long way. Just be sure to pay close attention to the air filter’s functionality to ensure it’s nonozone producing and nonionizing.

In addition, double-check the size of the room in which you plan to filter the air, as some HEPA filters are built for covering certain spaces and a maximum square footage. This roundup features filters of all sizes, and can be a good first step in your research.