Passive vs Active

Before considering which method of purification to use, consumers must first understand exactly how each technology works because this impacts how practical and effective they are.

For example, there are many passive technologies being sold as solutions for viral transmission prevention but one must remember a passive system can only perform its task if the following conditions are met:

– the pathogen or pollutant or particulate must first be drawn into the unit
– the pathogen or pollutant or particulate must be stationary and/or have passed very close to direct UV-C source and/or through an ionisation field.
– the pathogen or pollutant or particulate must not be smaller than the filter grading which excludes all viruses

If one considers it can take hours/days/never and lots of energy for these conditions to be met for airborne particles and never for surface contamination it is undeniable that the risk of viral transmission remains high with passive systems so they should not be used for this purpose especially if more effective alternatives exist.

There are other drawbacks with passive systems. Filters collect dust and quickly become clogged up which affects performance. They also become breeding grounds and harbours for viruses and bacteria which creates a health risk when filters are changed and allows pathogens to fall off and get passed back into the room. Also filters, UV-C and PCO technologies do not guarantee to remove or destroy all pathogens as they pass through the unit. For example, HEPA’s smallest grade is 0.3 microns yet all viruses are smaller than this so will pass straight through and back into the room. Also, UV-C and PCO are subject to the Inverse Square law and require “dwell time” to deactivate viruses, bacteria and odours meaning their effectiveness drops off considerably the further away the particle is (at 4 inches distant UV strength is reduced by 93.75%) and they have no effect on particles in a moving airstream. Ionisation only technologies cause particles to drop out of the air or collect on plates and viruses, bacteria or odours remain infectious and a health risk for hours before they are deactivated. Similarly, PCO and ionisation technologies are known to produce dangerous and even carcinogenic by-products including ozone and Formaldehyde.

With the patented active purification technology from RGF Environmental which mimics Earth’s natural air cleaning processes, the “oxidiser soup” of hydroperoxides, super oxides and hydroxide ions is released into the air stream and reaches into every cubic cm of indoor space, continuously breaking down and destroying viruses/microbials in the air and on surfaces as it goes and reverting back to water vapour and oxygen afterwards. This process is essentially the opposite of passive approaches. The air does not need to be passed through the device to be treated rather it treats all of the air and all of the surfaces in every part of the indoor space simultaneously and continuously. It is impossible for any passive technology to work like this.

These are the fundamental differences between active and passive technologies and they explain why it is important to understand how each technology works.

We recommend you see the following two videos taken from RGF’s IAQ training guides which explain the attributes, differences and drawbacks of Filtration, UV-C and PCO/Ionisation in better detail:

Passive: https://youtu.be/6KYCPZE2vmw

All of the air in a space must be pulled through a device/filter in order to be treated. In practice only air close to the unit is pulled through. Air further away from the unit is not treated.

Examples are HEPA/UVC/PCO/ionisation/non-thermal plasma. These technologies can be used for large particle filtration/coil disinfection/extending coil and filter life. In other words they can be used for AC maintenance but they should not be used as a solution to minimise person to person transmission risk of COVID (or any other form of virus/bacteria/germs in the open space). They do not provide continuous real time at source deactivation in every part of the air space and offer nothing for surface contamination. Similarly there are some technologies that produce dangerous levels of ozone or make claims that are either impossible or dangerous or both, such as hydroxyl “cascades” (due to the short lived and highly unstable nature of these oxidisers.)

Active: https://youtu.be/ZxUINHW4N18

“we were looking for a system that kills viruses and bacteria instantly the moment they are emitted into the air or touched onto surfaces to replace our passive UVC systems. REME ticks all the boxes and has helped reduce absenteeism and improve productivity”

RGF Environmental Inc has two patented active purification technologies which are used in millions of products (in-duct, standalone) across numerous vertical markets (residential, commercial, industrial, public sector/government, military) in over 60 countries around the world. They are termed Photohydroionisation (PHI) and Reflective Electro Magnetic Energy (REME). They use broad spectrum UV light shined onto a quad metallic hydrophilic catalyst cell, which continuously releases low and safe levels of hydro peroxide molecules into the air. This “plasma” is distributed throughout the entire indoor space, continuously sanitising the air and surfaces as it goes and creating a healthy environment free of pathogens, pollutants and particulates. In essence, this means that if a person were to enter a room and emit the virus into the air by coughing or touch it onto a surface, it would be instantly deactivated no matter where in the room the person is located. No passive form of purification can make this claim. Importantly, both PHI and REME technologies were developed over 15 years ago and are the most scrunitised, exhaustively tested and proven of all air purification technologies. RGF has recently been awarded the IAQ industry’s first ‘zero-ozone’ certification under the latest UL867 standards (0.005 ppm or less) by Intertek. Other technologies that claim to be zero ozone do not meet these new stringent requirements:

https://www.intertek.com/news/2020/08-12-intertek-sustainability-issues-first-zero-ozone-certification-to-rgf-environmental-group/