Types of Air Purifiers: How They Work, Pros, Cons & More

To get the most out of an air purifier, the key is to get the right one. However, when you hop online to browse, the number of models and jargon is overwhelming. What is HEPA-like and what does activated carbon do? And do these things even matter? So let’s go over some of the basics to avoid buyer’s remorse.

Types of Air Purifiers: Comparison

HEPA (High-Efficiency Particulate Air) Purifiers

HEPA (High-Efficiency Particulate Air) and HEPA-like air purifiers are among the most commonly used filtration devices for improving indoor air quality. They operate using a mechanical filtration system designed to capture airborne particles as air passes through a dense filter medium.

True HEPA vs. HEPA-like Filters

A True HEPA filter meets strict standards set by organizations such as the U.S. Department of Energy. Specifically, it must capture at least 99.97% of airborne particles that are 0.3 microns in diameter. This includes a wide range of contaminants like dust, pollen, mold spores, pet dander, and even some bacteria and viruses.

In contrast, HEPA-like, HEPA-type, or HEPA-style filters may resemble True HEPA filters in design but do not meet the same certified efficiency standards. These filters often remove larger particles such as dust and lint but are significantly less effective at capturing ultrafine particles. Because there is no regulatory requirement to label a filter as “HEPA-like,” the quality and effectiveness of these filters can vary considerably.

How HEPA Filtration Works

HEPA filters rely on a multi-layered mesh of fine fibers — usually made of fiberglass — arranged in a mat. As air flows through this dense medium, particles are captured through several physical mechanisms:

• Interception: Particles following the airstream come within one radius of a fiber and adhere to it.
• Impaction: Larger particles collide directly with the filter fibers due to their inertia.
• Diffusion: Very small particles, especially those under 0.1 microns, move erratically (Brownian motion) and are more likely to be trapped by the fibers.

Because of these mechanisms, HEPA filters are effective across a wide range of particle sizes, though they are particularly optimized for the most penetrating particle size (around 0.3 microns).

Particles Removed by HEPA Filters

True HEPA filters are capable of removing:

• Fine and coarse dust
• Pollen
• Mold spores
• Pet dander
• Smoke particles
• Some bacteria and viruses
• Other allergens and airborne particulates

HEPA-like filters, depending on their construction, may only be effective against larger particles like household dust and visible pollen.

Pros of HEPA and HEPA-like Air Purifiers

• True HEPA filters remove the vast majority of airborne particulates.
• They work through mechanical filtration, without releasing ozone or other byproducts.
• Most units only require occasional filter replacements and routine cleaning.
• A broad range of models and price points are available on the market.

Cons of HEPA and HEPA-like Air Purifiers

• HEPA filters cannot remove VOCs, smoke odors, or other chemical pollutants unless paired with an activated carbon filter.
• High-quality HEPA filters can be expensive to replace.
• Especially among HEPA-like products, effectiveness can be inconsistent and may not meet expectations.
• Dense filter material can reduce airflow, affecting overall circulation if the fan is weak.

Best Use Cases

• Excellent for removing allergens like pollen, dust mites, and pet dander.
• Useful in bedrooms, living rooms, and nurseries to improve overall air quality.
• True HEPA filters are commonly used in hospitals and clean rooms to control the spread of airborne pathogens.
• Effective at removing fine dust and particulate debris from the air.

Activated Carbon Air Purifiers

Activated carbon air purifiers use a specialized form of carbon designed to trap gas molecules and odors from the air. Unlike particulate filters such as HEPA, which physically capture solid particles, activated carbon works through a process called adsorption, where gases and chemical compounds adhere to the surface of the carbon.

Activated carbon is produced by treating ordinary carbon-rich materials — like charcoal or coconut shells—under high heat or with chemical agents. This treatment creates a highly porous structure with a vast surface area. These tiny pores allow activated carbon to trap and hold onto airborne molecules effectively.

How Activated Carbon Filters Work

When air passes through an activated carbon filter, volatile organic compounds (VOCs), odors, smoke, and certain gaseous pollutants adhere to the porous surface of the carbon. This process removes these unwanted gases from the air, reducing smells and harmful chemicals.

Activated carbon filters are often combined with HEPA or HEPA-like filters in air purifiers. The HEPA component handles particles such as dust and pollen, while the activated carbon section targets gases and odors, providing a more comprehensive cleaning effect.

What Particles and Pollutants Activated Carbon Removes

Activated carbon filters are effective at removing:

• Household odors (cooking smells, pet odors, smoke)
• Volatile organic compounds (VOCs) emitted from paints, cleaning products, and furniture
• Tobacco smoke components
• Some chemical fumes and gases
• Certain airborne chemicals linked to poor indoor air quality

It’s important to note that activated carbon does not capture solid particles such as dust, pollen, or allergens. Its strength lies specifically in neutralizing gases and odors.

Pros of Activated Carbon Air Purifiers

• Activated carbon excels at eliminating a wide range of household smells and chemical odors.
• Helps reduce VOCs and some airborne pollutants linked to respiratory irritation.
• When paired with HEPA filters, it offers broad-spectrum air purification.
• Does not produce harmful byproducts during the filtration process.

Cons of Activated Carbon Air Purifiers

• Activated carbon filters tend to be more expensive than standard particulate filters.
• Their adsorption capacity diminishes over time and use, requiring more regular filter changes.
• They do not remove dust, allergens, or microbes.
• Once saturated, activated carbon filters can release trapped pollutants back into the air if not replaced promptly.

Best Use Cases

• Ideal for kitchens, smoking areas, or homes with pets to reduce lingering smells.
• Helps reduce exposure to vehicle exhaust, pollution, and chemical odors.
• Removes VOCs emitted from paints, adhesives, and furniture.
• Beneficial for individuals with chemical sensitivities or respiratory issues related to odors.

Electrostatic Air Purifiers

Electrostatic air purifiers are a unique and somewhat niche type of air-cleaning device that use electrically charged filters to capture airborne particles. Unlike traditional HEPA filters that physically trap particles in dense mesh fibers, electrostatic purifiers rely on static electricity to attract and capture pollutants from the air. This method makes them reusable, low-maintenance, and generally quieter than many mechanical filtration systems.

How Electrostatic Air Purifiers Work

At their core, electrostatic air purifiers function using a two-step process involving ionization and collection:

• Ionization: As air flows into the purifier, it passes through an ionizer that emits a high-voltage electrical charge. This process causes particles in the air—such as dust, pollen, smoke, and other microscopic pollutants—to become electrically charged.
• Attraction and Collection: The charged particles then move through or across oppositely charged collection plates or filters. Thanks to the principles of static electricity, these particles are drawn to the plates and stick to them, much like how a statically charged balloon can pick up hair or dust.

Many models use washable filters or plates, which means you can clean and reuse them rather than replacing filters regularly, making them an eco-friendly and cost-effective option in the long term.

What Particles Do Electrostatic Air Purifiers Remove?

Electrostatic air purifiers are most effective at capturing small to medium-sized particles, especially those with a natural tendency to hold a charge or that can easily be charged by the ionizer. These include:

• Dust and dust mites
• Pollen
• Pet dander
• Smoke particles (from tobacco, cooking, etc.)
• Mold spores
• Bacteria and some viruses (to a limited extent)

However, they are less effective at capturing non-polar particles or gases, such as volatile organic compounds (VOCs), odors, and chemicals, unless paired with an activated carbon filter.

Pros of Electrostatic Air Purifiers

• No need to buy replacement filters, which reduces long-term costs.
• Less waste generated compared to disposable filter systems.
• Since they don’t rely heavily on fans, many models operate with minimal noise.
• Typically use less power than larger HEPA-based systems.
• Effective for capturing dust, pet dander, and pollen.

Cons of Electrostatic Air Purifier

• Some ionizers produce ozone as a byproduct, which can irritate the lungs and be harmful, especially in high concentrations.
• Without an additional carbon filter, they won’t remove VOCs or chemical fumes.
• Though the filters are washable, they need to be cleaned regularly (every 1–2 weeks) to remain effective.
• They generally don’t match the particle-capturing efficiency of true HEPA filters.

Best Use Cases for Electrostatic Air Purifiers

Electrostatic air purifiers are best suited for users who:

• Want a low-maintenance, reusable filter system.
• Have allergies to pollen, pet dander, or dust and need to reduce airborne irritants.
• Prefer a quiet air purifier for bedrooms, offices, or nurseries.
• Are looking for a cost-effective solution over time (no filter replacements).
• Don’t need strong odor or gas removal capability.

They’re also a good choice for pet owners, as pet dander is one of the particle types they handle well. Just make sure you’re okay with the regular cleaning cycle needed to keep them running efficiently.

UV-C Light Air Purifiers

These purifiers use ultraviolet (UV-C) light to kill or deactivate microorganisms like bacteria, viruses, and mold spores.

How UV-C Light Air Purifiers Works

Air passes through a chamber where it’s exposed to UV-C light (typically at a wavelength of 254 nm). This radiation damages the DNA or RNA of microorganisms, preventing them from reproducing and rendering them harmless.

What it removes:

• Bacteria
• Viruses
• Mold spores
• Some fungi

Pros of UV-C Light Air Purifiers

• Highly effective for killing airborne germs
• Works silently (no moving parts)
• Low maintenance if bulb is long-lasting

Cons of UV-C Light Air Purifiers

• Doesn’t remove dust, pollen, or allergens
• UV bulbs need regular replacement (usually once a year)
• Ineffective if air moves too fast through the chamber
• Some models can produce ozone

Best Use Cases for UV-C Light Air Purifiers

• People concerned about airborne pathogens (e.g., during flu season or in high-traffic areas)
• Supplementing other purifiers for extra disinfection

Ionic (Ionizer) Air Purifiers

Ionizers release negatively charged ions into the air that attach to airborne particles, causing them to clump together and fall out of the air or stick to nearby surfaces.

How Ionic Air Purifiers Work

Negative ions are emitted into the air. These ions bind to dust, smoke, and other particles, making them heavier and causing them to settle out of the air or be attracted to a collector plate.

It removes:

• Dust
• Smoke
• Fine particulate matter

Pros of Ionic Air Purifiers

• Quiet and energy-efficient
• No filters to replace
• Can reduce very fine particles in the air

Cons of Ionic Air Purifiers

• Doesn’t actually capture particles — just knocks them out of the air
• Can cause dirt buildup on walls/furniture
• Some models emit ozone, which can be harmful
• Not effective for allergens or odors

Best Use Cases for Ionizers

• Small rooms or minimalist setups
• People looking to reduce smoke or fine particles
• Only as a secondary or niche solution

Photocatalytic Oxidation (PCO) Purifiers

This is a high-tech air purification method that uses UV light + a catalyst (usually titanium dioxide) to break down pollutants at the molecular level.

How Photocatalytic Oxidation (PCO) Purifiers Work

UV light activates the catalyst, producing highly reactive hydroxyl radicals and superoxide ions. These destroy pollutants like VOCs, bacteria, and some viruses by breaking their chemical bonds.

What it removes:

• VOCs (volatile organic compounds)
• Odors
• Bacteria and some viruses
• Mold spores

Pros of Photocatalytic Oxidation (PCO) Purifiers

• Can break down harmful chemicals and gases
• Neutralizes odors
• Low maintenance once installed

Cons of Photocatalytic Oxidation (PCO) Purifiers

• Limited data on long-term effectiveness
• Doesn’t remove particles like dust or pollen
• Can generate trace amounts of ozone
• Expensive and not widely available in consumer models

Best Use Cases for Photocatalytic Oxidation (PCO) Purifiers

• Tech-savvy users or those with chemical sensitivities
• Environments with high VOC exposure (like newly renovated homes)

PECO (Photo Electrochemical Oxidation)

This is an advanced version of PCO used in Molekule air purifiers. It uses a proprietary process to break down pollutants at the molecular level.

How PECO (Photo Electrochemical Oxidation) Works

Similar to PCO but reportedly more efficient. UV-A light reacts with a specialized filter to oxidize and destroy organic pollutants (instead of just trapping them).

What it removes:

• VOCs
• Bacteria and viruses
• Allergens
• Mold
• Gases and chemicals

Pros of PECO (Photo Electrochemical Oxidation)

• Destroys a wide range of pollutants
• No ozone production (unlike many ionizers or PCO units)
• Targets both particles and gases

Cons of PECO (Photo Electrochemical Oxidation)

• Expensive upfront and ongoing filter costs
• Slower purification compared to HEPA
• Marketing hype vs. third-party validation still debated

Best Use Cases for PECO (Photo Electrochemical Oxidation)

• People with extreme sensitivities (e.g., asthma, MCS)
• High-end users looking for full-spectrum air cleaning

How to Choose the Right Type for Your Needs

If you’re not sure what you want out of your air purifier, you just want to generally improve your air quality, then a HEPA or HEPA-like air purifier is a great starting point. There is such a huge variety of them at every price point. Depending on how often you run them, the filters only need to be changed every six months to a year.

However, if you’re more interested in getting rid of odors, activated carbon filters are going to serve you better. There are air purifiers with a HEPA filter and an activated-carbon secondary. Carbon filters tend to be more expensive and require more frequent replacement.

HEPA and carbon filter air purifiers tend to be fairly loud on higher settings. People who are concerned about noise should check out an electrostatic air purifier. The technology relies on charging particulates in the air in order to get them to stick to the filter, so it doesn’t require a more powerful fan.

There are air purifiers that have multiple types of filters. For example, the Winix 5510 has a carbon, HEPA, and mesh filter. Getting a jack of all trades does increase the maintenance cost.

When it comes to size, most air purifier brands will list the ideal area of operation for each model. However, a more intuitive way of picking an air purifier is: do you want it to purify the whole room or just the air around you? Or put another way, does the air purifier sit on the table next to you, or does it sit strictly on the floor?

Do You Need More Than One Type of Purifier?

It all comes down to what you need. If you’re looking to purify every room of your house, you’re probably going to need multiple units. It would be advantageous to get one with a carbon filter for your kitchen or basement and HEPA or electrostatic units everywhere else.

However, if you’re not dealing with severe allergies, asthma, or high sensitivity to odors, that’s probably excessive. The average household can make do with a single large air purifier in the most trafficked areas, like the kitchen or living room. Or a smaller unit in each bedroom would also help cut down on allergy symptoms.

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