What type of air purifier is best for allergies?

Dr. Alana Biggers, assistant professor of medicine at the University of Illinois-Chicago, believes that air filters can be useful for those with allergies because they remove a majority of aggravating air particulates from any given room, though they don’t take away all particles. They filter what’s in the air and not pollutants that are settled into walls, floors, and furnishings.

If you decide to purchase an air purifier to reduce allergy symptoms, keep in mind that devices can vary. It’s important to consider what air pollutants you’d like to filter, and the size of the room you’ll be using it in.

What are you hoping to filter?

“There are many types of air filters that can remove particles at varying degrees. For example, HEPA filters, UV air filters, and ion filters are very good at removing dust, dander, pollen, and mold, but they are not great at removing odors,” notes Biggers.

She adds, “Carbon-based filters are good at filtering some particles and odors, but are not as effective in removing dust, dander, pollen, and mold.”

This table breaks down the different types of air filters and how they work.

Types of air filters How they work and what they target
High-efficiency particulate air (HEPA) Fibrous media air filters remove particles from the air.
Activated carbon Activated carbon removes gases from the air.
Ionizer This uses a high-voltage wire or carbon brush to remove particles from the air. The negative ions interact with the air particles, causing them to attract to the filter or other objects in the room.
Electrostatic precipitation Similar to ionizers, this uses a wire to charge particles and bring them to the filter.
Ultraviolet germicidal irradiation (UVGI) UV light inactivates microbes. This doesn’t pull out the microbes from the space entirely — it only inactivates them.
Photoelectrochemical oxidation (PECO) This newer technology removes very small particles in the air by making a photoelectrochemical reaction that removes and destroys pollutants.
Permanently installed air cleaners Not considered air purifiers (which are portable), heating, ventilation, and cooling (HVAC) systems and furnaces can remove pollutants from the air. They may use filters like the ones listed above, and they may also include an air exchanger to clean the air.

How big is the area you’d like to filter?

The amount of space in your room should also guide your selection. Check how many square feet a unit can handle when evaluating it.

You can look for the clean air delivery rate (CADR) to determine how many particles and square feet an air purifier can reach. For example, HEPA filters can clean the smallest particles like tobacco smoke and medium and large particles like dust and pollen out of the air and may have a high CADR.