People with asthma may find air purifiers help reduce indoor asthma triggers by filtering particles, such as dust or smoke, and circulating clear air back into the room.

An air purifier is a device people can use in the home to help remove indoor pollutants or allergens.

While some research indicates that air purifiers may benefit people with asthma, reducing or eliminating the trigger source may be the most effective strategy.

This article explores how effective air purifiers are for people with asthma, what to look for in an air purifier, and other steps to improve indoor air quality.

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An air purifier is a device that helps remove indoor pollutants from the air.

The device usually contains at least one filter and a fan. As air passes through the purifier, the filter captures fine particles, such as dust, smoke, and other pollutants and allergens. The purifier then circulates clean air back into the room.

Air purifiers only work on certain solid and liquid particles in the air, not on gases such as radon or volatile organic compounds (VOCs). VOCs are chemicals that many household products, including paint and cleaning solvents, release into the air.

Dust, smoke, and other pollutants or allergens can trigger asthma symptoms. Air purifiers may help reduce some of these triggers.

A 2018 review looked at how strategies to reduce indoor allergens affected asthma. The researchers found that single strategies, such as using an air purifier alone, did not generally improve asthma measures. The review’s authors suggested that a combination of methods may help improve asthma outcomes, but further research among larger populations is needed.

One 2018 study looked at the effects of air purifiers on 50 people with asthma. A randomized group of participants used air purifiers in their bedrooms, while a control group did not. The results indicated some significant improvements in both air quality and respiratory function with the use of air purifiers. This study also called for further research into the role of air purifiers in asthma treatment.

According to a 2016 review, portable high-efficiency particulate air (HEPA) purifiers reduce particles in the air by around 25–50% and reduce asthma symptoms and attacks. However, research suggests they do not reduce the gas pollutants in tobacco smoke, such as nicotine, in the air.

The Asthma and Allergy Foundation of America (AAFA) states that air-cleaning devices such as air purifiers might help people with asthma, but removing as many sources of environmental triggers as possible is the most effective way to reduce symptoms.

The Environmental Protection Agency (EPA) also points out that while air purifiers can help reduce indoor pollution, they cannot eliminate all indoor air pollutants.

When choosing an air purifier, people may wish to consider the following factors:


Look for an air purifier with a high-efficiency filter. HEPA purifiers remove at least 99.97% of particles 0.3 micrometers in diameter or larger. This means just 3 in every 10,000 particles this size will not become trapped by the filter.

Room size

A person should choose an air purifier appropriate for the size of the room they plan to use it in. They should also make sure the device has a suitable clean air delivery rate for the room in question. The Environmental Working Group recommends using a filter that replaces the air volume in a room two to three times every hour.


The AAFA recommends air purifiers with certified asthma- and allergy-friendly filters, which remove almost 98% of allergen air particles.


Some ionizing air purifiers produce ozone, which can irritate the respiratory system. According to the EPA, ozone does not remove air particles, and ionizing air purifiers may not be as effective as HEPA filters.

Although an air purifier may help remove indoor allergens and pollutants, reducing or eliminating environmental triggers may be the best first-line approach for people with asthma.

Ways to reduce indoor allergens and improve air quality include:

  • using a vacuum with a HEPA filter one to two times a week
  • using allergen-resistant bedcovers
  • keeping humidity in the home below 50%, as hot and humid living spaces can encourage mold and dust mites to breed
  • avoiding smoking in the home
  • removing shoes on entering the home, reducing the presence of outdoor allergens such as pollen
  • regularly cleaning bathrooms, basements, or any tiled areas to prevent mold from growing
  • grooming any pets outside the home to reduce animal dander and washing pet bedding regularly
  • controlling any pests, such as mice or cockroaches

People may also find the following tips help them manage their asthma:

  • maintaining a moderate weight
  • eating a heart-healthy diet, including plenty of fruit, vegetables, and foods that provide the appropriate vitamin D intake
  • exercising regularly and talking with a healthcare professional if asthma is preventing any physical activity
  • managing stress through relaxation techniques or speaking with a healthcare professional to help manage any mental health challenges
  • avoiding smoking and secondhand smoke, including vapor from e-cigarettes
  • developing a regular sleep routine
  • getting a flu vaccine each year, as flu may increase the risk of asthma attacks
  • having an asthma action plan to help manage symptoms and prepare for attacks
  • taking any asthma medications a doctor may prescribe and attending any routine checkups

Air purifiers use a filter and fan to remove certain allergens and pollutants and circulate clean air back into the room.

Some evidence suggests that using air purifiers may help reduce asthma symptoms, though further research is needed. Reducing environmental triggers in the home through regular cleaning and eliminating mold or pests is important for people with asthma.

Experts recommend people choose an air purifier that is appropriate for the size of the room in question and uses a HEPA filter. People with asthma should avoid using ionizing air purifiers, as these may produce ozone and irritate the respiratory system.