Air Cleaning Technology Comparisons

Fortunately, it appears the worst of the Covid crisis is behind us.  Unfortunately, Covid remains a deadly disease that may develop more transmissible variants as time goes on.  Being able to function in the coming months requires being able to ensure everyone who enters our facilities will breathe safe air.

A number of different technologies purify room air, but which ones are best? Let’s take a look at the advantages and disadvantages of each.

Portable vs. Fixed

Fixed systems are always superior to portable systems. Generally, fixed systems are more powerful, but more importantly, they can be placed for optimum airflow. A portable system placed in the wrong spot can be ineffective or even create an airflow pattern that helps pathogens move from one person to another.

Filter Media

Filtration systems remove contaminants by passing air through a medium that traps and holds them.


  • Effective and easy to use. The HEPA filter in particular is a gold standard of effectiveness. Widely used in hospitals, they remove 99.99% of all contaminants that are 0.3 microns or larger.


  • Filters must be changed out on a regular basis.
  • Differing filter technologies have a wide range of effectiveness
  • Pathogens trapped by filters may remain alive and infectious.

Ozone Generators

These systems produce ozone and distribute it in the area to be purified.


  • Ozone can be very harmful to pathogens, because it can cause organic materials to oxidize and break down, killing the germ or virus.


  • Ozone is harmful to people for the same reason!
  • Ozone can also degrade nonliving organic materials, such as plastics, rubber, and cloth.
  • Currently, the EPA has not approved any ozone generator for occupied spaces.
  • Using it safely in a non-occupied space means using seals to ensure that ozone doesn’t penetrate areas where humans work.

Ion Generators

These units push charged ions out into the air, causing particles to become charged. They then cling to surfaces, where they cannot be breathed in


  • No filter changes


  • They may produce ozone, which is unpleasant or even harmful to those with respiratory issues.
  • Infectious pathogens are now on surfaces, requiring wipe downs with disinfectant.

Plasma Air Purifiers

These cleaners use an arc of electrical current to ionize or destroy contaminants.


  • These units have the same advantages as ion-based purifiers, but also are very effective at killing pathogens as the arc’s energy destroys their membranes and DNA.


  • Most units are designed to operate with a filter.
  • They not only may produce ozone, they can sometimes introduce other harmful gasses (such as carbon monoxide) into room air and may create more particulate matter unless they have a filter system.
  • They are too large and expensive for single-room use

Ultraviolet Germicidal Irradiation (UVGI)

These units use UV-C ultraviolet light, irradiating pathogens and damaging their DNA until they can no longer function


  • Over 99% of biological hazards are destroyed by UV-C light.
  • No ozone, chemicals, or odors are produced
  • Simple on-off use.


  • UV-C is very dangerous to humans and can cause cancer and severe vision damage. It must be used in a closed casing.
  • Irradiation kills pathogens but does not trap them or other particulates.

Why We’ve Chosen Air Guardian

As you can see, the best of both worlds in air cleaning is a system that kills pathogens effectively and traps particulate matter, without producing odors or ozone. The compact, ceiling-mounted Air Guardian system fits that description. Simple to use and install, this fixed, maintenance-free system passes room air through advanced carbon glass HEPA filters before sending it through a 19-foot tube lined with UV-C LED’s. This exposes it to virus-killing light throughout its journey. The tube is circuitous by design, keeping the Air Guardian’s size to just 2 feet by 4 feet.

If you think the Air Guardian may be the right solution for your space, get in touch with Thayer today and we can discuss your needs and this opportunity for increased Covid safety.