from the study concluded that such devices, which include systems used to administer UV-C
light or radiation, can improve survival rate of individuals. At the front lines, UV-C light is proven
to be effective in sanitizing N95 filtering facepiece respirators (N95 FFRs). Medical staff must
deal with the shortage in N95 respirators and other protective devices by disinfecting the
equipment and reusing them. This practice was tested by researchers from the University of
Nebraska Medical Center, through administering a 300 mJ/cm
2
dose of UV germicidal
irradiation on N95 FFRs. The scientists highlighted that single-stranded RNA SARS-COV-2 can be
inactivated with UVGI exposure of 2-5 mJ/cm
2
, which was exceeded by the researchers in the
study.
UV 254 nm light is capable of eradicating common dust mites (
Dermatophagoides pteronyssinus
[D. pteronyssinus]
and
Dermatophagoides farinae [D. farinae]
). A 2012 study
13
demonstrated
such capabilities through direct UV exposure. Researchers tested exposure times ranging
between 5-60 minutes and distances between 10-55 cm. An immediate mortality success rate
of 100 percent was achieved when the UV lamp was positioned at 10 cm distance for 60
minutes. Egg-hatching capabilities were reduced by a whopping 50 percent for both types of
mites. Increasing the duration of exposure also increased the mortality rate of UV treatment,
while increasing the distance between the UV lamp and the samples decreased such rates.
Interestingly, UV treatment had a more devastating effect on the eggs compared to the adult
mites. Based on the results of the study, the scientists cited UV 254 nm light to be effective in
disrupting the lifecycle of mites at the embryonic stage to reduce the proliferation of allergens.
6.0 Conclusion
Both far-UV 222 nm and conventional 254 nm wavelengths are effective in eliminating viruses,
bacteria, spores and other disease-causing microbes. As these bands fall within the UV-C
germicidal range of 200 nm to 280 nm, the UV rays utilize the same mechanism to disrupt and
inactivate microorganisms. A closer look at the properties of 222 nm UV bands suggests that it
is not easily absorbed by water vapor. Therefore, for long irradiation distances in the air, the
far-UV band could be less effective (but still capable of inactivating viruses and bacteria and
achieving above 99% inactivation success rates) in environments saturated with water vapor.
The safety benefits of 222 nm UV light dictate its applications in buildings and busy locations.
The wavelength is considered to be eye and skin safe for humans, as it does not cause the
formation of potentially cancerous CPDs. Additionally, 222 nm excimer lamps are mercury-free,
energy efficient and environmentally friendly. The units can be deployed in occupied areas,
public locations and busy facilities without imposing devastating health risks.
Traditional 254 nm UV light is a very powerful sanitation solution that leverages fluorescent or
induction units. From a health perspective, the UV band can cause skin burns and corneal
damage. This type of artificial light source is most effective when deployed in empty rooms,
cabinets, UV boxes or ovens and via handheld devices. UV 254 nm lamps should not be
