Bundled UV-C rays are intended to help make the transmission of Sars-CoV-2 indoors less likely. Researchers have developed a kind of invisible curtain that is supposed to kill viruses in the air with the help of short-wave UV radiation. According to the developers, their system kills over 99 percent of pathogens and is harmless to humans thanks to an automatic shutdown device. They want to deliver the first models as early as April 2022.
The Sars-CoV-2 coronavirus is mainly transmitted via virus-containing droplets and aerosols that are emitted by infected people when they cough, sneeze, speak and breathe. The infectious aerosols are a problem especially indoors because, unlike larger droplets, they do not sink quickly to the ground, but remain in the air for a long time. It is known that Sars-CoV-2, like many other pathogens, can be killed with the help of UV-C radiation. However, this extremely short-wave UV light can cause skin and eye damage in humans and is considered to be carcinogenic. For this reason, UV-C radiation has so far mainly been used in closed systems.
Bundled UV-C light
A team led by Andreas Wieser from the Ludwig Maximilians University in Munich is now using UV-C light for a kind of invisible protective wall, which is intended to curb the spread of Sars-CoV-2 and other pathogens indoors while at the same time allowing unrestricted freedom of movement in the room should enable. “Our system can be hung from the ceiling like a lamp to separate rooms,” explains Wieser. “The UV-C light is focused downwards. Like a protective curtain, pathogens are inactivated as soon as they ‘float through’ on aerosol particles. ”Since the UV-C light destroys the genetic make-up of the pathogen, it acts equally against all variants of the virus.
One challenge in the project was to bundle the UV-C light in such a way that it does not emit from the designated area. The researchers solved this problem with the help of reflectors within the system and UV-absorbing elements on the floor. In this way, legal requirements such as limit values for UV radiation in the workplace can be complied with. So that people can move around the room unhindered – even through the invisible partition – the system also has an automatic switch-off device: As soon as an object or part of the body approaches the radiation area, the UV radiation switches off and only comes on again when the radiation area is free.
Protective wall and air filter
The researchers tested the protective effect of their system with various model organisms, including, in addition to Sars-CoV-2, the bacteria E. coli and Staphylococcus aureus. They assumed the air speed to be ten centimeters per second. The air moves about as fast a meter away from someone who has just sneezed. When Sars-CoV-2, E. coli and S. aureus crossed the UV curtain at this speed, more than 99 percent of them were inactivated. “In most rooms, there will be a lower air movement speed, which leads to an even higher rate of inactivation,” the researchers write.
They also combine their invisible protective wall with an air filter: “With a patented protective mechanism, the system disinfects the breathing air in the room by sucking it in and slowly blowing it into the illuminated area of the UV-C light wall,” explains co-author Christoph Haisch from the Technical University of Munich. “In addition to the direct barrier effect of the light wall, this prevents an accumulation of infectious aerosols in the room.”
Alternative to respirators?
From the researchers’ point of view, their system could in future enable people to spend time together indoors again without a mask. “The most effective way to protect yourself against pathogens that are transmitted by aerosols are respiratory masks that fit very tightly and have no leaks,” the researchers write. Medical masks, however, would offer loopholes for aerosols and FFP2 masks would often not fit perfectly in practice. Air filters alone, on the other hand, could prevent high concentrations of infectious aerosols in a room, but not block direct transmission.
Your UV wall, on the other hand, like masks, could also act as a barrier to direct transmission. While the air in the room can circulate unhindered, the room for the pathogens would be divided into smaller virtual rooms whose invisible borders they cannot overcome. The developers now want to bring their anti-virus walls to market as quickly as possible. “Parallel to the scientific validation of the system, we have already started to prepare production with well-known suppliers from the automotive industry,” reports Reiner Prohaska, who founded the start-up Smart United to market the system. “From the beginning of January we will start planning the rooms with our first customers. From the beginning of April we will be delivering the first UV-C light virus protection walls – with the aim of giving people back a piece of normalcy. “
Source: Andreas Wieser (LMU Munich) et al., MedRxiv, doi: 10.1101 / 2021.12.16.21267937