Informational Guide

Comparing Air Purifiers Vs Ionizers

Generally, with air purifiers, you have two options. HEPA filters or an ionizing air filter. We will compare both types for homeowners.

by Ian Haynes

Allergens in the air can cause all kinds of problems, from stuffy noses and runny eyes to sore throats and sickness. If you suffer from seasonal allergies, then you need a way to get allergens out of the air.

You have two options at this point: a HEPA air filter or an ionizing air filter. We will discuss the two and which is better.

The acronym HEPA stands for High Efficiency Particulate Air [Filter] and is a special kind of air filter that is extremely effective at removing particulates in the air. HEPA air purifiers can remove particles as small as 0.3 microns in diameter for a theoretical removal rate of 99.97%.

  • Diffusion –
    HEPA filters use the diffusion of dust particles into a tightly packed fiber matrix to capture larger particles that could cause respiratory irritation.
  • Interception –
    HEPA filters also work by directly intercepting particles as they travel through the air, capturing them in fiber layers.
  • Impaction –
    Large particles cannot avoid fibers as they curve through the airstream. Impaction filters are most effective with large air volumes.
How HEPA Filter Works

Pros & Cons of HEPA Air Purifiers

What We Like
  • Removes 99.97% of particles
  • Highly efficient design
  • Long-lasting
  • Highly effective for particles
  • Maintains humidity
What We Don’t Like
  • Relatively expensive
  • Does not remove VOCs
  • Can inculcate mold spores

What Is an Ionizer & How Do They Work?

Ionizers are air purification technology that use electrical charges to remove particulates from the air. Ionizers creative negative ions. The electrical charge from these negative ions attracts positively charged ions, which carry dust and bacteria. Ionizers are good for removing larger particles but might have trouble with very small particles.

  • Particulate pollutants.
    Ionizers use electrical charges to attract other large particles that might get in the air. The negative ions attract positively charged ions to remove things like dust and other pollutants.
  • Gaseous pollutants.
    Ionizers do not work on gaseous pollutants, including VOCs or odors. Ionizers may also produce ozone which can interact with gaseous products. Ozone can be harmful in large amounts.
How Ionizer Air Purifier Works

Pros & Cons of Ionizers (Ozone Generators)

  • Remove larger particles
  • Can remove bacteria
  • Low energy
  • Removes dust and allergens
  • Electric plates are highly effective
  • Can create ozone, which is toxic in high concentrations
  • Electric plates can get dirty

HEPA Air Purifier vs. Ionizers (Ozone): Side By Side Comparison


HEPA filters are common in industrial settings, where they are used to filter out fine particles. They are also found in very high-end air filters that are used for homes. Ionizers are relatively less expensive and are commonly used in residential environments.


HEPA air filters remove most harmful particulates, but they cannot remove gaseous compounds like volatile organic compounds or odors. Ionizers also cannot remove gas or odors. Also, ionizers can create ozone (O3) by interacting with the atmosphere, and ozone can be toxic in large quantities.

Read about the safety of ionic air purifiers in this article.

Scope of contaminants.

Both HEPA air filters and ionizers are good at removing more significant pollutants such as dust or allergens. HEPA filters, however, can remove smaller particles than ionizers. Neither HEPA  filters nor ionizers can remove gaseous products in the atmosphere. Also, ionizers may not trap bacteria and viruses because they are too small.

Design and style options.

HEPA filters come in a wide variety of air purifying units and may be upright, horizontal, or tabletop humidifiers. Similarly, ionizers can come in several shapes and styles. No matter the style, you should be able to operate the devices using an input pad to set cycles and intensity.

Coverage area.

The coverage area depends on the air purifier that you get. In general, a decent mid-grade air purifier will cover anywhere between 500-1,000 sq. feet. The most powerful air filters are industrial grade and will cover up to 3,000 sq. feet or more.


All filters and purifiers need to be cleaned and maintained. Filters get dirty over time and need to be replaced, and the electric plate ionizers need to have the plate screens cleaned of dirt and debris. A good HEPA filter can last between 2-3 years, depending on how much filtering it’s doing.


In general, HEPA filters are almost always more expensive than ionizers. Some ionizer models are small and only cost about $50.

The absolute cheapest HEPA filter purifiers you are likely to find are probably around $100, give, or take $10—the reason is that HEPA filters are relatively expensive to manufacture. HEPA filters also need to be changed regularly.

People Also Ask (FAQ)

Which cleans cigarette smoke, HEPA, or ionizer?

Both HEPA and ionizer air purifiers purify smoke very well. However, HEPA filters probably do it better because they can capture all tar particulates.

Which type kills mold spores in the air?

HEPA filters can remove mold spores, but they may not kill them outright. If humidity is high, mold spores can grow in HEPA filters if left uncleaned. Ionizers, on the other hand, will not kill mold.

Can you clean and reuse HEPA filters?

Generally no. While you probably could clean a HEPA filter and reuse it, it would be difficult to do, and you would probably break the filter in the process. It’s best to buy a new one when you need it.

How often do you change HEPA filters?

A good HEPA filter should last about 2-3 years, depending on where it is being used. It will last longer in places where there is less general air pollution.


Both HEPA air filters and ionizers are good ways to keep the air around you clean. So if you suffer from allergies, consider looking into one or the other today.

Last Updated on June 29, 2022

Ian Haynes

Ian Haynes is an HVAC writer, and researcher. He has worked on hundreds of articles relating to home cooling, heating and air quality with a vast knowledge of the technical aspects of these types of appliances. Outside of his work, Ian likes exploring Brooklyn with his Labrador. Learn more about the AC Lab team here.