Guardian Angel Series MTB 800 HEPA UVC air purifiers use a combination of HEPA and UVC air purification methods. Two heavy HEPA filters are located just in front of two powerful 18 Watt UVC light disinfection sources, two electrostatic filters, and two charcoal filters. MTB 800 is the only unit that enlist all of these methods to sanitize air. This combination of systems is the most effective industrial grade air filtration unit available. 

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Air filtration systems must trap particles as small as .3 microns (330 nanometers) to qualify as a HEPA (High Efficiency Particle Absorbing) filter. HEPA filters use three different methods to trap particles in a woven network of fibers. Diffusion impedes the travel of particles, and in some cases the particle may stick to the fibers. Interception uses a curved weave to help channel and grab larger particles. Impaction uses a special weave to channel the flow of particles into dead ends.  These barriers are very good traps for particles like pollen, dust, fungus spores and bacteria; however, virus particles are small enough to travel through HEPA filters. 

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Very small particles such as the Coronavirus are measured in nanometers. The SARS-CoV-2 virus that causes Covid-19 is approximately 125 nanometers in diameter. HEPA filters are designed to a trap particles as small as 330 nanometers. A micron is 1000 nanometers, so HEPA filters alone cannot stop the passage of viral particles. Our HEPA UVC air purifiers use four different methods to impede and deactivate the virus that causes Covid-19.

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Viral particles are more like seeds, than living organisms. They must come in contact with a living host and invade its outer cellular membrane to grow and reproduce. These viral particles called virions are strands of RNA (genetic material). Their lifespan is limited in most cases to hours. Research had confirmed that Covid-19 particles caught in HEPA filtration can remain viable up to 4 hours. The HEPA disinfection filter will catch or impede the travel of some virions, but because of the size limitations, HEPA filter manufacturers cannot honestly claim these units will remove viral particulate. Trapped particles can be dislodged, and aerosolized by air flow through the unit.  

 

Some filtration units combine the HEPA system with charcoal enhanced filters, but charcoal only removes certain gases like formaldehyde. Other systems use an electrically charged metal filter, that is supposed to attract negatively charged particles like a magnet. There is very little,  "peer reviewed" research to prove the efficiency of these systems, but they probably do trap some some viral particulate. 

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The Guardian Angel line of HEPA UVC interior air disinfection equipment uses industrial quality versions of all of the above mentioned systems. UVC is a proven, recognized sanitizer that damages reproductive genes in pathogens like bacteria, fungus, and viral particles. The EPA and CDC recognize the effect of UVC ultraviolet light, and they have compiled research data that list how much exposure to UVC is required to deactivate certain pathogens. Since some viral particles and other pathogens are moving with the air, a powerful UVC light disinfection source, located in close proximity is needed to obtain enough exposure to deactivate them. Viral particles and other pathogens trapped by the HEPA mesh are quickly deactivated, as are any escaping particles.