Amid the COVID-19 pandemic, germicidal lighting has been eyed for indoor disinfection. Bob Karlicek, the director of the Lighting Enabled Systems and Applications (LESA) Center at Rensselaer Polytechnic Institute led a team of engineers who designed and built a UVC system to disinfect masks for reuse. In addition, he has been answering some of the biggest questions people have surrounding this potential tool in the current global public health crisis.
These are a few examples:
1. Can UVC radiation kill SARS CoV 2?
Yes, several groups have demonstrated that UVC radiation can quickly deactivate the SARS CoV 2 virus that causes COVID-19. To be effective, however, the delivery dose needs to be high enough and the required dose depends on several environmental factors (surface or airborne, relative humidity, and other environmental factors) that impact the delivery of UVC radiation to the virus’ RNA. The higher the dose, the faster the process, and the greater the percentage of virus deactivated.
2. Can UVC LEDs be used for germicidal applications?
Absolutely, and there is considerable published evidence for the effectiveness of UVC LEDs in germicidal applications including SARS CoV 2. Also, the output power, reliability and cost-effectiveness of UVC LED solutions are continually improving with continuing research on the design and manufacturing of UVC LEDs. Note that both UVC mercury lamps (254 nm) and UVC LEDs have lifetimes that are considerably shorter than LEDs used in solid-state lighting, so that should be factored into the design of GUV systems using either technology.
3. How can UVC sources be used safely around people?
So long as humans are not in the direct line for exposure to the UVC radiation there should be no issues. Ordinarily, UVC systems are used only when people are not present or in disinfecting air (either inside of ductwork of HVAC systems or with specially designed optics to irradiate the upper portions of room-air) with little or no radiation to the people below. Some UVC lamps come with presence detection systems that turn off when persons approach, but these systems will have to have very low false-negative error rates (turning on when the system falsely thinks that people are not present).
You can read more questions and answers here. If you'd like to interview Robert Karlicek, please click on his ExpertFile profile.
Robert Karlicek Director, Center for Lighting Enabled Systems & Applications (LESA) & Professor, Electrical, Computer, and Systems Engineering
Applications of LEDs in Lighting, sensing, disinfection, displays and control systems