UVC Light Choice


Available UVC Light Choices...

When Farlite'sTM co-founders decided to create Farlite™ to provide a service that would block the aerosol transmission of pathogens, they realized they needed to make the right decision on which wavelengths of UV light they should feature.  It was an important decision that required learning about what choices were available, the suitability of their means to attack pathogen replication, and which would be best able to be integrated into their product vision.  Having no commitments to utilize specific products, they were free to innovate and incorporate best elements into their service.  As service providers they are focused on  building lasting relationships with customers by delivering peak performance at all times. 


Achieving this goal included determining the best choice of Ultraviolet Germicidal (UVC) light upon which to build the service. The contestants were few - as only 222 nanometer (nm) and 254 nanometer (nm) light wavelengths were available in existing lamp technologies of current supply chains.  One concern was that many commercially available lamps were dirty lamps,  i.e., lamps that include several peaks at differing wavelengths, some of which are dangerous. Filters are required to exclude any undesirable wavelengths if they pose environmental or human health risks.


A workable solution requires that the aerosol pathogens get a sufficient dose of radiation in a relatively short period of time as air currents are always carrying the pathogens around, especially when the HVAC system is on.  If they pass through a zone of UVC radiation too quickly, they may not be sufficiently inactivated.


UVC Light is Like Sunburn...



SUNBURN = (Exposure Time)   x  (Sun Strength)  x  (Skin Sensitivity)


Depending on how bright the sunlight is at a particular time of day, it will take more or less time to get a sunburn.  Some people have skin that is not at all sensitive while others get burned very quickly and some wear protective clothing or coatings.  Our usual experience is that short exposures are mostly safe while long exposures are harmful.  Overexposure to UVC light is much like sunburn.


EXPOSURE TIME = (Path Length) / (Air Speed)


INACTIVATION   =  (Exposure Time) x (UV Light Intensity) x (Pathogen’s Sensitivity)


For pathogens, exposure duration depends on air flows that move pathogens about while intensity depends on lamp power and assembly design.   Intensity, exposure duration and the pathogen's UVC light sensitivity are the critical factors in pathogen inactivation. 


FarliteTM UVPhasor's Barrior Zones give calculated doses to pathogens.  Since different pathogens have different sensitivity, it is best if the phasor can vary the strength of the UVC light it projects.  The FarliteTM UVPhasor can adaptively adjust UVC light energy levels while the Phasor design prevents exposure to humans by never permitting the lamps to project downward below the  horizon.


UVC 254 nm Has a Longer Wavelength...

It is understood that 254 nm UVC poses risks to humans over-exposed to it.  With long enough exposure it can severely irritate eyes and skin reminiscent of too much sun exposure.  Unlike sun exposure that is principally from UVA and UVB,  UVC penetrates  a little but not far enough to reach the cancer forming layers of skin.  254 nm UVC poses some more risk to eyes than does 222 nm.  These observations are moot however if, in use, 254 nm UVC never strikes humans.   FARLITETM has discovered that striking humans is unnecessary and avoids it. 

UVC 222 nm light has a much shorter wavelength.  This gives it the ability to break apart oxygen molecules that recombine with other oxygen molecules to create ozone.  This is a known hazard associated with UVC light with any wavelength shorter than 230nm.  The level of ozone produced is low but the production is continuous.   UVC 254 nm light's wavelength cannot produce ozone.  


Filtered UVC 222 nm light attacks and damages proteins as opposed to damaging reproductive elements. UVC 254 nm light attacks and damages the pathogen's DNA, essential to reproduction and spread.  Thus, these two very similar approaches are slightly different -- and both are effective.  It is true that Farlite'sTM technology can use either 222 nm or 254 nm in its UVPhasors.  There are times that UV 222 better addresses inactivation requirements just as UV254 seems more effective in the upper-air.  Farlite™  supports both in their appropriate situations.


FARLITETM Selects the Power of 254nm...

FarliteTM chose the 254 nm light  that:


  • Has the favored method of pathogen inactivation being damage to the reproductive capabilities (DNA/RNA) rather than the 222 nm light that inactivates by damaging proteins found in the spike glycoproteins and some of the DNA/RNA chains.  UV 222 is well absorbed by many proteins while 254 is more closely tuned to DNA and RNA nucleic acids that affect reproduction.
  • Under presently available technology, UV 222 delivers less energy to the targets while UV 254 is the wavelength that provides stronger light intensity - causing quicker inactivation in a shorter distance of travel. 


We wanted short exposure times since pathogens are carried about by air, in many cases fast moving air. We chose to engineer lamp assemblies and deployment practices so that our UVC light is projected from the horizon upwards and never projected onto people thus eliminating concerns that we could harm them. FARLITETM also provides  Cloud-based Monitoring  to ensure that light levels are properly maintained.