Do Air Purifiers Work? Research, Best Practices, And More - Healthline

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HealthlineSubscribeDo Air Purifiers Actually Work?

Medically reviewed by Angelica Balingit, MD — Written by Kristeen Cherney and Karen Lamoreux — Updated on March 24, 2025

What it is
How they work
Differences
Air purifier types
Effectiveness
Types of contaminants
Health improvements
Benefits
What they won't work for
Other options
Products
Takeaway

Portable air purifiers are good for helping air out your home, reducing or increasing humidity, limiting access to air pollution, and generally keeping your home air clean. However, you need to get the right purifier for your needs.

Home air purifiers often claim to be reliable solutions for indoor air quality health concerns, but do they really clean your household air?

The short answer is yes, but only to a degree. It all depends on what you want an air purifier to do in your home and how well you match the specific air purifier to your goals.

Read on to find out how portable air purifiers work and what exactly they do.

What is an air purifier?

This article concerns portable air purifiers, which are devices designed to filter the air in a single room, not your whole home. Whole-house air purification systems are available, but they are tied into the heating, ventilating, and air conditioning (HVAC) system of a home or facility.

Most current portable air purifiers are designed to filter both particles and gases. But one filter can’t do the entire job. So many air cleaners contain multiple filters, one for particles, another for gases, and still more for gases, chemicals, or odors.

How air purifiers work

Despite their differences, portable air purifiers generally work the same. They use fans to draw air in through one or more filters, trap various contaminants, and then re-circulate the cleaner air back into the room.

Portable air cleaners vary in weight, but they can usually be moved from room to room. Some can be mounted on the wall. And there are even wearable and desktop versions too.

How do air purifiers differ?

Air purifiers vary according to:

type and number of filters they use
square footage they cover
how much air they draw through the filter (expressed in cubic feet per minute)
how well they collect pollutants from indoor air (expressed as a percentage efficiency rate)
clean air delivery rate (CADR), or the amount of clean air they deliver
weight and ease of portability
what contaminants they target
the strength of the pollutant source

All these variables are important in your consideration of a portable air purifier. To choose wisely, you have to know both the dimensions of the area you want to clean, the capabilities of the particular air purifier you’re considering, and what contaminants you’re targeting.

Before investing in an air purifier, you may want to invest in an air quality home test to determine what contaminants you have in your home.

Probably the most important variable in an air purifier is the filter. Your best choice to filter particles is a device with a HEPA filter, which is designed to collect at least 99.5% of particles in the air that are 3 microns or less in size. Generally speaking, this type of particle includes pollen, dust, moisture, bacteria, viruses, and dirt.

The effectiveness of a HEPA filter depends on how tightly bound the fibers are. This is usually expressed as a rating from MERV 12 to MERV 17. You want a filter that is at least MERV 13.

Another important variable is the clean air delivery rate (CADR). This is the amount of clean air your device will re-circulate. The general rule is that the CADR of your air cleaner should be equal to at least two-thirds of the room’s area.

For wildfire smoke, the CADR should be higher, equal to the number of square feet of the room you are trying to clean.

Some air cleaners specify CADRs according to the three specific types of pollutants: tobaccosmoke, dust, and pollen. These correspond to small-, medium-, and large-sized particles, respectively. You can choose a device with the right CADR for the contaminants you are targeting.

What types of air purifiers are there?

Most portable air purifiers are one of three types:

Filtered air purifiers that capture airborne pollutants and trap them in one or more filters.
Electrostatic air purifiers that create charged particles to trap particles in a filter.
UV light air purifiers that use UV light against certain contaminants, such as viruses and bacteria.

There is concern that electronic air cleaners (including the last two types of air cleaners in this list) can produce ozone gas and other pollutants that may be hazardous to health. Therefore, filtered air purifiers are considered the safest type for home use.

Neither the Food and Drug Administration (FDA) nor the Environmental Protection Agency (EPA) certify air cleaning devices. The EPA also does not recommend any particular air cleaning devices or manufacturers.

Are they effective?

This is the question people ask the most about air purifiers. The short answer is yes, but only to a degree. The full answer all depends on a number of factors:

the types of contaminants in your home
the ventilation in your home
the size of the space you are trying to clean
the type and number of filters the air purifier uses
the CADR rate of the air purifier
how much you can control the sources of contamination
how consistently you use the air purifier

The issue is complicated by the fact that in addition to being airborne, particles can embed themselves in furniture, bedding, and carpeting, as well as collect on hard surfaces like walls and ceilings. So your housecleaning habits can affect how much work your air purifier has to do.

What household contaminants should concern me?

Most contaminants are collectively described as particulate matter, or simply PMs. PMs refer to airborne particles, which are usually classified as either

PM2.5 particles that are 2.5 microns in diameter or less, or
PM10 larger particles that are 10 microns in diameter or less

A micron is a unit of length equal to one-millionth of a meter. Fine PM, the term for the smaller PM2.5 particles, cause the most health concerns because they can penetrate human airways and enter the lung air sacs. Air purifiers in general are effective in removing airborne fine PM.

Let’s take a look at the various contaminants you might be dealing with in your home and see how air purifiers might be able to help.

Allergens

Allergens are substances that can trigger symptoms in people with allergies, asthma, or respiratory conditions. According to the Asthma and Allergy Foundation of America, 8 of every 10 people in the United States are exposed to dust mites, and 6 of every 10 are exposed to cat or dog dander.

Some of the most common allergens found in indoor spaces like your home and schools include:

Pollen: an outdoor allergen that can enter indoor spaces via doors, windows, and other ventilation.
Pet dander: microscopic skin flakes shed by animals with fur or feathers, like cats, dogs, and birds.
Animal dander from involuntary infestations, like rats or mice: similar to dander from pets, but usually much more concentrated and uncontrollable. Research shows that 75% to 80% of U.S. homes have detectable mouse allergen.
Cockroaches: cockroaches shed allergens, chitin, endotoxins, and other substances during their lifetime.
Dust mites: microscopic-sized mites that feed on human shed skin and thrive in humid environments. Research shows that between 30% to 60% of children with asthma are sensitized to dust mites, and their symptoms worsen with exposure.

What does the research say?

One study cited a number of reports that HEPA air purifiers can benefit people with varied allergies by reducing the concentration of indoor allergens, including pollen, house dust-mite (HDM) allergens, and dog dander.

But not all research agrees, especially when it comes to dust mites and animal dander.

One research review concluded that air cleaners have little meaningful effect on dust mite allergens because these allergens ride on larger particles that quickly settle to surfaces and are not caught by air cleaners. It also said evidence failed to show that air cleaners significantly reduced airborne animal allergens or pollen.

Mold

Research shows that mold can be especially harmful for people with asthma and other lung conditions, especially in children. Mold is a fungal growth that forms and spreads on various kinds of damp surfaces. Its presence indicates a problem with excess moisture.

Mold reproduces by producing spores, which become airborne. Inhaling these spores or touching mold can trigger a mold allergy. Symptoms might include sneezing, throat and nose irritation, runny nose, and red or itchy eyes.

What does the research say?

According to the EPA, portable air cleaners do not resolve a mold problem. They may remove some of the airborne mold particles, but they don’t eliminate mold. To do that, you have to resolve the excess moisture and clean up the mold.

Smoke

Indoor smoke can come from many sources, including:

tobacco, including cigarettes, cigars, and other smoked substances, such as marijuana
e-cigarettes, or vaping
incense
wood-burning stoves and fireplaces
idling cars and buses

What does the research say?

One study found that air purifiers do little to remove nicotine from indoor air. Other research showed that HEPA air purifiers can reduce smoke particles in the air, but not the non-particle nicotine or other gaseous components of smoke.

This makes air purifiers useful during short-lived indoor smoke from landscape fires, but not totally effective for protecting from the adverse health effects of tobacco smoke, either primary or secondary.

Smoking cessation in households and cars is preferable over air filters. But if this is not possible in a home, a HEPA air filter may reduce smoke particles and be a better intervention than nothing.

Gaseous pollutants

Gaseous indoor pollutants may include:

inorganic gases, like carbon monoxide and nitrogen dioxide
ozone
volatile organic chemicals (VOCs) that are not attached to particles

Volatile organic compounds (VOCs) are gaseous emissions from thousands of products containing organic chemicals, including many household products. Organic chemicals vary greatly in their health effects from highly toxic to no known health effect.

To filter gases, you need to choose a portable air cleaner with an activated carbon filter or otherfilter designed to remove gases. HEPA filters are generally ineffective against VOCs. Also, some air cleaners are targeted only to specific types of gases or VOCs.

What does the research say?

There are many air purifiers that claim to reduce VOCs in your home. But when the American Chemical Society tested four consumer-grade portable air cleaners that claimed to remove VOCs from indoor air, researchers found the actual VOC removal to be minimal.

More startling, they found that the “cleaned” air that some of the air cleaners delivered actually contained additional VOCs and other byproducts known to be harmful to human health.

The lesson here is to check the specific product packaging or labeling on an air purifier to be sure you get one designed to filter the VOCs you’re targeting.

Do air purifiers improve your health?

According to the World Health Organization, household air pollution exposure can lead to serious health conditions such as stroke, heart disease, chronic obstructive pulmonary disease (COPD), and lung cancer.

Can portable air purifiers make a difference?

The EPA says portable HEPA air cleaners have been shown to benefit allergy and asthma symptoms, as well as cardiovascular health. But the amount of benefit can be small, and the benefits may not be solely due to air cleaners.

What does the research say?

The EPA reported statistically significant improvement in respiratory health and allergy or asthma symptoms in a research review of eight studies.
In another EPA research review, 10 out of 11 studies showed statistically significant improvement in cardiovascular health with the use of air cleaners.
Regarding gaseous pollutants, the EPA points to research showing that that HEPA air purifiers can sometimes reduce these pollutants in a home, but it cautions that the studies are limited, with inconsistent results.

Air purifier benefits

Air purifier benefits vary by about the same factors as the air purifiers themselves, including

the type and number of filters
the CADR rate
the targeted pollutants
how consistently and appropriately the device is used

But when used effectively, air purifiers can have benefits in your home, including:

Allergies. Air purifiers can help reduce allergic symptoms by lightening the allergen load of your indoor air.
Asthma. Air purifiers can lessen triggers of asthma symptoms and attacks, from contaminants like dust, smoke, and pollen.
Dust. Your air purifier may lessen the amount of dust particles, which are usually 5 microns or less in size, within the range of most HEPA air purifiers.
Animal dander. Your air purifier my help reduce dander in your home from your pet cat, dog, or bird.
Particulate matter (PMs). HEPA air cleaners with sufficient CADR can reduce concentrations of indoor PM2.5 (the smaller particles) by an average of 50% or higher.
Viruses. Some air purifiers can reduce airborne particles containing viruses. To do so, it must be able to remove very small particles ranging from 0.1 to 1 microns, according to the EPA. Manufacturers report this as a particle removal efficiency (for example, “removes 99.9% of particles as small as 0.1 um [or microns]” In 2022, came one of the first reports of the removal of airborne SARS-CoV-2 concentrations in a hospital environment using combined air filtration and UV sterilization.

What they won’t work for

No air purifier can eliminate all the pollutants from your home, or even 100% of one pollutant.

Portable air purifiers also may not be particularly useful for:

mold
nicotine and other gaseous pollutants
animal dander, especially from involuntary rodent infestations
cockroach allergens
some types of VOCs
larger, heavier allergens, such as dust mites and pollen, which may settle to the ground more quickly than air purifiers can capture them

Other ways to clean your indoor air

Despite their potential benefits, air purifiers may be futile if you don’t take other steps to create cleaner air in your home, too. The EPA recommends using air purifiers as a third option in the three basic strategies for improving home air quality:

Control the source of the contaminants.
Improve your home’s ventilation.
Use effective air cleaners.

You can help reduce the amount of contaminants in your indoor air space by doing the following:

Clean rugs, carpeting, and fabric furniture often.
Wash bedding in hot water once a week.
Bathe pets often.
Keep your home at optimal humidity between 40% to 60% to help prevent mold and dust mites.
Never smoke inside the house or car.
Switch to nontoxic cleaning products.
Ventilate your home by opening a window and running fans.
Change HVAC air filters every 30 to 90 days, according to the Asthma and Allergy Foundation of America.

What about plants?

For people who think houseplants might reduce household levels of contaminants, the EPA has sad news. No current evidence shows that they do. Also, be sure not to overwater. You run the risk that the damp soil may promote growth of microorganisms.

Products to consider

There are many different portable air purifiers to choose from. We’ve rounded up The Best Purifiers to get you started.

The bottom line

Portable air purifiers work best in conjunction with

ventilating your home
optimizing home humidity
controlling the source of contaminants
housecleaning

Consider starting your search for an air purifier by clarifying what exactly you want it to do in your home. Know the dimensions of the space you want to clean and which contaminants you are targeting. Then match up your expectations with the specs of an appropriate air purifier.

Ideally, here’s what you want in an air purifier:

designed for the size of your room
targets the type of contaminants in your home
has a high CADR rate
has a HEPA filter with at least a MERV 13 rating

If you have any underlying health issues, such as asthma and allergies, talk to your doctor about ways you can improve your indoor air quality to manage your symptoms. Never stop taking any medications without talking to your physician first.

You can also look for air purifiers and filters that are certified asthma and allergy friendly devices by the Asthma and Allergy Foundation of America. An allergist may also have specific recommendations tailored to your needs.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Environmental Protection Agency (EPA). (2025). Air cleaners and air filters in the home.https://www.epa.gov/indoor-air-quality-iaq/air-cleaners-and-air-filters-home
EPA. (2022). Air cleaners, HVAC filters, and Coronavirus (COVID-19).https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-and-coronavirus-covid-19
EPA. (2018). Guide to Air Cleaners in the Home, 2nd edition.https://www.epa.gov/sites/default/files/2018-07/documents/guide_to_air_cleaners_in_the_home_2nd_edition.pdf
EPA. (2024). Ozone generators that are sold as air cleaners.https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners
EPA. (2018). Residential air purifiers: A technical summary.https://www.epa.gov/sites/default/files/2018-07/documents/residential_air_cleaners_-_a_technical_summary_3rd_edition.pdf
EPA. (2024). The Inside Story: A Guide to Indoor Air Quality.https://www.epa.gov/indoor-air-quality-iaq/inside-story-guide-indoor-air-quality#three-basic
How can I control indoor allergens and improve indoor air quality? (2015).https://aafa.org/allergies/prevent-allergies/control-indoor-allergens/
Jia-ling L, et al. (2018). Efficacy of air purifier therapy in allergic rhinitis.https://apjai-journal.org/wp-content/uploads/2019/01/2EfficacyAPJAIVol36No4December2018P.pdf
Lindsley WG, et al. (2021). Efficacy of portable air cleaners and masking for reducing indoor exposure to simulated exhaled SARS-CoV-2 aerosols — United States, 2021.https://www.cdc.gov/mmwr/volumes/70/wr/mm7027e1.htm
Matsui EC, et al. (2016). Indoor environmental control practices and asthma management.https://publications.aap.org/pediatrics/article/138/5/e20162589/60439/Indoor-Environmental-Control-Practices-and-Asthma
Morris AC, et al. (2022). The removal of airborne severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) and other microbial bioaerosols by air filtration on coronavirus disease 2019 (COVID-19) surge units.https://academic.oup.com/cid/article/75/1/e97/6414657
Park KH, et al. (2020). Effects of air purifiers on patients with allergic rhinitis: A multicenter, randomized, double-blind, and placebo-controlled study.https://pmc.ncbi.nlm.nih.gov/articles/PMC7393300/
Potentially hazardous ozone generators sold as air purifiers. (n.d.).https://ww2.arb.ca.gov/our-work/programs/air-cleaners-ozone-products/potentially-hazardous-ozone-generators-sold-air
Volatile organic compounds' impact on indoor air quality. (2024).https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality
World Health Organization. (2024). Household air pollution [Fact sheet].https://www.who.int/news-room/fact-sheets/detail/household-air-pollution-and-health
Ye Q, et al. (2021). Real-Time laboratory measurements of VOC emissions, removal rates, and byproduct formation from consumer-grade oxidation-based air cleaners.https://pubs.acs.org/doi/10.1021/acs.estlett.1c00773

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Medically reviewed by Angelica Balingit, MD — Written by Kristeen Cherney and Karen Lamoreux — Updated on March 24, 2025

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What is an air purifier?

How air purifiers work

How do air purifiers differ?

What types of air purifiers are there?

Are they effective?

What household contaminants should concern me?

Allergens

What does the research say?

Mold

What does the research say?

Smoke

What does the research say?

Gaseous pollutants

What does the research say?

Do air purifiers improve your health?

Can portable air purifiers make a difference?

What does the research say?

Air purifier benefits

What they won’t work for

Other ways to clean your indoor air

What about plants?

Products to consider

The bottom line

How we reviewed this article:

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