The COVID-19 pandemic brought UVC technology back in the spotlight. This 100-year technology helped in the past to deal with other outbreaks such as measles and tuberculosis and now is being used in hospitals to reduce microbial burden.
We cover some potential benefits of UVC light related to COVID-19 prevention in past articles.
In this article, we get into more specific details, based on the latest research.
What is the UV dose required to inactivate Sars-Cov-2? The UV dose required to inactivate Sars-Cov-2 will depend on several factors. Surface disinfection will require a different dose than UV air disinfection.
Surface Disinfection
UVC light is already used in hospitals to decontaminate masks and other personal protective equipment. An effective mask decontamination has to reduce the microbial burden, not harm the fit or filtration performance of the mask, and should not present a chemical hazard. In April 2020, The National Institute for Occupational Safety and Health (NIOSH) found that UVC irradiation ticks all the requirements above, and is one of the top choices for mask disinfection, based on its potential to disinfect [2].
Studies evaluated the required dose of UVC light to inactivate the novel coronavirus, considering past research into other coronaviruses like SARS-Cov-1 and MERS, as well as current research looking specifically at Sars-Cov-2. The UVC dose in lab conditions ranges from 3.7mJ/cm2 to 22mJ/cm2 dose to inactive – 99.9% (3-log) and 99.9999% (6-log) respectively.
In real-life, the virus is often hidden or shaded from direct UVC light. For this reason, researchers use higher UV doses- 1,000 – 3,000 mJ/cm2 to ensure 99.9% deactivation, which is the current disinfection goal recommended by the US The Centers for Disease Control and Prevention (CDC).
In addition to disinfecting masks, UVC light can be used for surface disinfection- especially high touch areas such as keyboards, mice, and phones.
UV Air Disinfection
Can whole-room UV-C effectively inactivate the SARS-CoV-2 virus?
Here is the answer provided by a recent in-depth review of research provided by the International Commission of Illumination (CIE). UV-C could be used as a supplemental infection control measure and would have a great value in hospital settings. While there are different ways to disinfect the air, CIE suggests the so-called “upper air” UVC devices because they offer the safest, most effective application of UV-C. Whole room disinfection using suspended fixtures directing the ultraviolet light downward can also be applied. CDC did evaluate UVC technology and provided specific guidelines for the use of UVC lamps in both upper rooms and air handling units for air disinfection (as a supplemental control measure). While the exact UVC dose for SarsCov-2 inactivation is not mentioned in this report, previous studies found that other viruses like influenza, polio, and hepatitis require UV doses between 6,600 -8,000 µWs/cm2 for 99% (2 log reduction), using UVC for HVAC systems.
Considerations
Think about UVC light as a disinfectant for surface, air, and water. It is important to avoid any skin or eye exposure to this light, to avoid tissue damage. You may have heard of far UVC light as being safe for humans, but more research is needed. Rooms can be disinfected outside the business hours, with proper equipment.
When it comes to UV air disinfection, there are many variables to consider ie air flow, humidity, the distance of microbe to the UV light, irradiation time, and more. That’s why you need to work with the team of UVC experts from IZAK Scientific to get the right device and training on how to use UVC technology for optimal results.
