Atmos VS. OTher Technology

UV systems disinfect by passing air through ultra-violet light. With these systems the air can only be treated if it comes into direct contact with the light field, and certain contaminants (the ones that aren't already resistant to UV) do not get treated because they are not exposed to the UV long enough. UV systems do not treat odors, VOCs, or gaseous compounds, and UV is also dangerous when exposed to humans. 

Also sometimes advertised as HEPA filters, these are generally decent filters, as they have proven to be 99.97% efficient in trapping particles .3 microns and larger. For this to work though, air in HVAC systems must pass through these filters, which in turn restricts airflow and increases energy costs. These type of filters can only filter out contaminated air from entering an area, but cannot treat the source of the contaminants. 

This type of system also uses UV light, but with a catalyst (such as titanium) to produce reactive oxygen species called hydroxl radicals. This process can inactivate certain bacteria and viruses, but has no effect on odors or particulate matter. Also, some PCO systems are known to emit an undesirable amount of ozone into whatever environment it is being used in, which can be very harmful to humans over an extended amount of exposure. 

Needlepoint ionizers are ionization needles that produce positive and negative ions. They can be incorporated into any HVAC systems, or can also be used as standalone units. Not much research has been done around the technology, and it is not effective on particulate matter, odor, mold, bacteria, or virus removal. That means that there is no noticeable difference whatsoever in the areas these systems are implemented, and research has proven that ions quickly recombine in occupied space. 

In a process called 'absorption', pollutants are trapped in a carbon substrate. Although they are known to make HVAC systems more efficient, it is passive technology and relies highly on airflow to bring contaminants to the filter, which is the only way it can be effective. Carbon filters do not sanitize or disrupt the reproductive cycle of mold, bacteria, and specific influenza. They are also known to not be very energy efficient. 

One of the most common types of air purifiers on the market today They change particles by generating single polarity ions to pass through the unit to attract to an oppositely charged collector cell. With this process, the units can only treat air that passes through the collector cell, and they are mostly ineffective against bacteria, spores, odors and VOC compounds. These systems also use a lot of energy to produce these ions.