Different types of air filters (Hepa, Ionic, UV, Carbon)

When air contaminants are inhaled, the body’s natural defense system is more vulnerable to small particles below 0.5 microns. Different air filters are able to filter out contaminants on different levels, and can be applied to different needed situations.


Examples of some common air contaminants and their size in microns:

  • Pollen (5-100 microns)
  • Mold (2-20 microns)
  • Pet Dander (0.5-100 microns)
  • Dust Mite Debris (0.5-50 microns)
  • Bacteria (0.35-10 microns)

HEPA Filtration

HEPA stands for High Efficiency Particulate Air and this air purification technology was originally developed during World War II to remove radioactive dust particles from the air to protect soldiers’ respiratory systems. Today they are often used to filter household air with the capacity to trap 99.97% of all airborne particles that are as small as 0.3 microns in size and 95% of minute particles down to 0.1 micron.

HEPA air filters are the most recommended by Allergists and Doctors because of their ability to remove the majority of air contaminants down to the microscopic level.

HEPA filters are able to remove all of the contaminants in the chart listed previously because they are larger than 0.3 microns. HEPA filters alone do not capture chemicals, fumes, and cigarette smoke because their microns are smaller than 0.3. This is why it is important to purchase a HEPA air filter that includes an activated carbon filter that will capture these allergens that the HEPA cannot.


  • Removes dust, pollen, mold spores, dust mites, and other allergens.
  • Removes most bacteria
  • Solid particles captured are not released into the air again


  • It does not remove chemical fumes, cigarette smoke, or odors
  • Not as effective in capturing the smallest viruses
  • Micro-organisms captured in filter can breed or reproduce, resulting in increased micro-organism populations

Activated Carbon Filters

Activated Carbon filters have small absorbent pores that chemically react to pollutants as they pass through the filter. This causes the pollutants to bond with the carbon and become trapped. These purifiers are effective at clearing smoke, odors, chemicals and even gases from the air. Activated Carbon filters are rarely used alone to purify air, and are often used in conjunction with other filters.


  • The most absorbent filter available
  • Captures chemical fumes, gases, cigarette smoke, and odors
  • Does not release contaminants back into the air


  • Does not remove dust and other allergens
  • Does not remove micro-organisms

Ionic Filter

An air ionizer is built around a negative ion generator. This generator sends out a stream of negative ions that attract positive airborne dust and allergen particles in the air. As a result, these particles become too heavy to remain airborne and fall to the floor. As the majority of surfaces in a room are positively charged, the particles from the ionic air are attracted to these surfaces as well. This means that the area around the ionic filter tends to get dark spots on nearby walls and floors. Some ionizers however, have special electrostatic precipitators that trap particles on a metal plate. To remain effective, these plates need to be cleaned regularly.

Ionizers are a relatively inexpensive way to clear second hand smoke. However, if you have a problem with dust or pollen an ionizer air purifier may not be the best choice because the particles are not completely eliminated. The main health concern related to ionic air purifiers is the fact that they produce ozone as a byproduct. When ozone is inhaled directly into the lungs, it can pose a health risk. The EPA classifies ozone as a toxic gas that causes lung damage, triggers asthma attacks, and can even lead to increased risk of death. These are all facts that need to be taken into consideration when purchasing the right air purifier.


  • Removes ultra-fine particles as small as 0.01 microns
  • Sterilizes bacteria, viruses, smoke, and other toxic fumes
  • Very quiet because there are no fans or motors


  • Removes particles from the air, but not from the room. Particles land on floors, walls, & furniture and may be easily put back in the air.
  • Produces ozone as a by-product
  • Does not remove odor

Ultraviolet Light Air Purifiers

This purifier uses a UV light that has electromagnetic radiation that will destroy bacteria and other pathogens by breaking the molecular bonds in their DNA. UV air filters kill these particles without any actual filtration, but rather use rays of ultraviolet light to eliminate them as they pass.
A UV light air purifier works well to kill bacteria, viruses, molds, and yeasts that may remain in the air. Unfortunately they will not take care of dust, allergens, or solids in the air. UV light can be beneficial to those who get sick often because they help prevent illness and diseases. Air purifiers with UV filters are often used in sterile environments such as hospitals, kitchens, daycares, and labs. In residential use, they are great for controlling mold.

Optimal performance is attained when these air filters are used in unison with other types of air filters. That way they can work together to remove a wider spectrum of air contaminants such as odor, chemical fumes, and allergens that UV air purifiers do not remove.

Some ultraviolet filters generate ozone to kill bacteria and sometimes may not be properly dispersed, posing a serious health concern. If purchasing an Ultraviolet light air purifier, make sure to find a system that does not produce ozone.


  • Ability destroys micro-organisms, such as germs, bacteria and mold.
  • Helps prevent illness and disease


  • Does not remove most allergens, dust, or solids in the air
  • Does not remove chemical fumes, gases, or cigarette smoke


Now that you understand the different types of air filtration your first step is to identify what contaminants you are trying to remove. By having an idea of what you want to remove you can choose the most effective air filter to do so. For example, if you are a cigarette smoker a single HEPA filter will not be sufficient. A carbon activated filter will be more effective in removing the odors. If you are more interested in removing allergens such as dust, bacteria, pet dander, and mold it would be recommended to purchase a purifier with a HEPA filter because these are more effective in removing larger particulates.

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