Air Filter VS Air Purifier: The Final Showdown

Air purifiers and air filters are not the same, even though both share a common goal of capturing airborne contaminants. In this post, we will focus on the differences between an air filter and air purifier, the pros/ cons, how to use them, and ultimately which one you should go for. Let's begin.


What Is The Difference Between An Air Filter And An Air Purifier?

There is a big distinction between the two. An Air filter is essentially a filter built-in into your HVAC system; it will not work independently. An air purifier is a stand-alone appliance that will work independently to clean the air. Both systems are built differently to target different types of airborne contaminants and toxic fumes. An air purifier may consist of multiple filters that can remove the finest particles that an air filter can’t. Many people often confuse air filters with air purifiers which is not the case.

The table below shows the breakdown of what an air filter can remove versus what an air purifier can.

What Do Air Filters And Air Purifiers Remove?

Types Of PollutionsAir PurifierAir Filter
PM10 particles (Dust/ Hair/ Soil/ Fiber/ Lint)YESYES
Dust mitesYESYES
Pet danderYESYES
Mold/ Mildew/ FungusYESYES
Biological pollutantsYESYES
Toxic fumes (Tobacco smoke/ VOCs/ Radon/ formaldehyde)YESPARTIALLY

What Are Air Filters And How Do They Work?

An air filter is a filtration built into the home’s central HVAC system. The primary role is to keep the air clean by capturing large airborne particles like dust, debris, hair, fiber, and lint before reaching the AC or furnace system. Without the pollutants building up, your HVAC system will run as smoothly and efficiently as intended.

Common Types Of Air Filters

  • Washable pre-filter – Only large PM10 particles due to the less dense filter media setup. However, it is the most cost-effective filter as it is washable and reusable.
  • Activated carbon filter – A secondary filter behind either a pre-filter or HEPA filter. Carbon filters are made from porous charcoal or carbon material that primarily absorbs smoke and odors. Carbon filters are disposable filters and must be replaced when worn out.
  • HEPA filter – AKA High-Efficiency Particulate Air filter. The benchmark filter is used in every residential and commercial HVAC system, including hospitals. A certified HEPA filter will trap 99.97% of microscopic particles as small as 0.3 microns.

Air filters are made of a dense layer of fiberglass, pleated paper, or mesh media that traps the particles that pass through like a sieve. Some air filters come with an additional activated carbon filter that absorbs smoke and odors through chemical adsorption. When the HVAC system is switched on, there will be a constant flow of air drawn and pushed through the air duct. The air filter located between the air duct and furnace will trap the particles that pass through before releasing the clean air back into the home. The whole cleaning cycle will continue until the HVAC system is switched off.

The quality of the air filter is measured by MERV (Minimum Efficiency Reporting Value) rating. The higher the MERV ratings, the smaller and more particles can be captured, but at a much higher cost. Most standard air filters are between MERV 3-8 ratings with an <70% filtration efficiency for 3-10 micron-sized particles. The EPA requires at least a MERV 8 filter in a building that can capture common lead dust, mold, and pollen. We recommend going between air filters with MERV 17-20 ratings similar to a HEPA/ ULPA filter. The filter will remove 99.97% to 99.99997% of microscopic particles, including lead, viruses, and Legionella bacteria.

The Drawbacks Of Air Filters

An air filter only works with your existing HVAC system, so it is not as flexible as an air purifier. You cannot bring it around the house or outside during work or travel. Filter installation and replacement can be tricky, and you may need an HVAC expert to do it for you. Compatibility might be an issue as some air filters might be too large to fit into an older HVAC system.

What Are Air Purifiers And How Do They Work?

An air purifier is a device that uses a series of filters and fans to clean the air. The powerful fan will draw air in via the air inlets. The dirty air will have to pass through multiple filters, starting with a pre-filter that captures large particles like dust, hair, and lint. Next, a True HEPA filter traps microscopic particles like mold, pet dander, and germs as small as 0.3 microns. For smoke particles, an activated carbon filter will neutralize incoming gaseous pollutants and foul smells. Depending on the filtration, some air purifiers even come with a UV-C light or negative ion generator to remove any remaining air particles. Purified air will be released back into the room, and the cleaning cycle will continue until the air purifier is switched off.

Common Types Of Air Purifiers

  • HEPA air purifiers – The most popular and effective type. Pull air in and trap them via the weaving fiberglass-made HEPA filter before distributing clean air back out. Only go with a United States Department of Energy (U.S. DOE) certified True HEPA filter over an inferior HEPA-type filter.
  • UV air purifiers – Irradiate a spectrum of wavelengths to kill germs, bacteria, and viruses by altering their DNA chromosomes. Unlike a HEPA air purifier that merely traps the filter, the disinfected pathogens will have no chance of growth. It will generate an insignificant amount of ozone within FDA regulation.
  • Photocatalytic oxidation cleaner – AKA PCO air purifier. A NASA based on research technology eliminates contaminants as small as 0.001 microns through photocatalytic oxidation. 300 times smaller than what a HEPA filter can remove. Like UV cleaner, there is a low level of ozone byproducts production.
  • Air ionizer/ Electrostatic precipitators – Also known as filter-free air purifier. A filterless technology diffuses negatively charged ions into the surrounding air and bonds with positively charged airborne particles. The heavier, bonded particles will fall and adhere to the surface area in the room unless there is a collector plate/ rod to collect them. While a cost-effective air cleaner, its effectiveness leaves much to be desired.
  • Ozone generatorA waste of money. We refuse to categorize it as an air cleaner. It is not approved by FDA, health professionals, or government agencies. The release of toxic ozone is detrimental to your health and should be avoided at all costs.

The Drawbacks Of Air Purifiers

It is not all perfect with an air purifier. Some disadvantages can be hard to overlook, such as bulkiness. Unlike an air filter tucked inside an air duct, an air purifier will take up some interior space. If you have limited space in your room, the existence of an air purifier can be a hindrance. Performance-wise, it cannot capture particles that are adhered to a surface area like the floor. An air purifier will also need to work in an enclosed room with closed windows for optimal performance. The high purchasing price and recurring filter replacement costs can burden those on a tight budget. Air purifiers will also generate background noise that can irritate you during sleep or work.

Final Thoughts

There is no wrong choice here. Whether you are a team air filter or air purifier, having either or both will help immensely improve the air quality in your home. You will be less at risk of exposure to allergens, bacteria, and viruses. Cough, flu, sore throat, and headache will become less likely to occur with cleaner air. Seasonal illnesses will be a thing of the past.

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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