Do Air Purifiers Really Work?

Sure, warmer weather brings out the best in nature—everything is green, in bloom, and bright. But for kids with seasonal allergies and their parents, it can be a time of misery. Itchy eyes, sneezing, and coughing can zap the fun out of playing outside in that fresh air.

"In the spring season, pollens and mold can trigger symptoms of nasal congestion, runny nose, sneezing, eye watering, and itching," says Amiinah Kung, M.D., doctor of allergy and immunology at Northwestern Medicine Central DuPage Hospital. In the summer, tree pollens and grass pollen tend to be most problematic, according to Meng Chen, M.D., a pediatrician at Stanford Children's Health.

The symptoms of seasonal allergies occur when your child's immune system identifies environmental triggers as harmful invaders, and they can present themselves even before your child heads to preschool. "Developing seasonal allergies requires multiple seasons of exposure, and that is why infants are not susceptible to seasonal allergies but may develop symptoms as they age," says Natasha Burgert, M.D., a board-certified pediatrician. "The distinct pattern of seasonal symptoms can be seen as early as the age of 2."

While there are lots of ways to treat and prevent these seasonal allergies in kids of all ages, one that has been hotly debated is using an air purifier. Read on for expert answers on the efficacy of air purifiers for allergy management before adding this pricey investment to your cart.

What Is an Air Purifier, and How Does It Work?

Air purifiers are quite literally named. "Air purifiers use fans or ions to attract small particles in the air and then capture them on a filter, which removes them from circulation," says David Stukus, M.D., pediatric allergist and immunologist at Nationwide Children's Hospital.

According to the University of Massachusetts Amherst, the most effective ways to improve indoor air quality are:

• Eliminating sources (cleaning)
• Ventilating by opening windows and cleaning furnace filters
• Air cleaning (air purifiers with HEPA filters)

In other words, air purifiers are among several indoor air quality management tools, but they are not a magic bullet capable of resolving air quality issues alone. In addition, it is important to understand their limited ability to impact circulated air throughout the home. Other than the immediate space or room where they are located, they can not impact small particles distributed on different levels or rooms.

Can Air Purifiers Really Help Seasonal Allergies?

There are mixed opinions on whether air purifiers are a reliable solution to help prevent seasonal allergies.

The pros

On the one hand, air purifiers work to clear the air of the stuff making your child miserable. "Allergens in the air in your home can trigger allergy symptoms, and air filtration can help decrease the amount of airborne allergens in your home and can help with allergy and asthma symptoms," says Dr. Chen.

A 2020 study evaluated the effects of air purifiers on participants with allergic rhinitis (nasal allergies). Study participants were randomly assigned to active or placebo air purification groups for six weeks. In the active group, allergy medication usage was significantly reduced.

Another 2018 study also evaluated the efficacy of air purifiers in participants with nasal allergies. After four months of use in their bedrooms, researchers found that the HEPA air purifiers effectively reduced particulate matter and dust mite allergen concentration and improved allergy symptoms.

Some studies have also looked specifically at air purifiers and children. For example, a 2017 study in the Journal of Asthma found that after 12 weeks of using an air purifier or placebo, the air purifier group had significantly reduced nasal symptoms.

The cons

However, air purifiers have limited capabilities and perform best in small spaces. They can also be expensive and difficult to maintain.

"Air purifiers are very low on the list of recommended approaches to allergen avoidance inside the home," says Dr. Stukus. "They don't work well for outdoor pollen allergens and have very limited use for indoor allergens, which often settle on carpeting and furniture and do not remain airborne for long. There is also routine maintenance involved with changing filters."

Research on the topic is limited and often contains small sample sizes. "There is not enough significant evidence to recommend air purifiers for allergy control in children," says Dr. Burgert.

Choosing the Best Air Purifier

If you're looking to try out an air purifier as part of your allergy management, there are a few things to look out for, including:

• Making sure it has a HEPA filter
• Finding one that is suited for your room size
• Using and cleaning it properly according to the model instructions

"We recommend air purifiers with a HEPA filter; HEPA stands for high-efficiency particulate air," says Dr. Meng. "Stand-alone air purifiers are designed for a single room, so you should use it with the door closed and check that your air filter can accommodate the size of the room. And since air purifiers can be expensive, if you only have one air purifier, we recommend putting it in the bedroom since you spend a consolidated amount of time there while sleeping."

Besides a portable air purifier, there are also ways you can install air purifiers into your home's ventilation system. "If you have a central ventilation and/or heating/cooling system, you can also buy an air filter for this system," says Dr. Meng. "Look for the MERV (minimum efficiency reporting value) rating of the filter. Ideally, the MERV rating should be at least 11, and higher values are better. And make sure you clean or replace these filters regularly." According to the American College of Allergy, Asthma & Immunology, filters should be replaced every three months.

The Bottom Line

Air purifiers can help with seasonal allergies, but they may not be the most effective method. "Air purifiers only filter the air in a very confined space inside the home, which limits their benefit," says Dr. Stukus. "Other than the immediate space or room where they are located, they are not going to impact small particles distributed on other levels or rooms."

That said, several studies show that air purifiers show promise in a layered allergy and asthma mitigation strategy. If you want to try one out, read the product specifications carefully to ensure it will work in the space you need it for.