Existing UV tech could reduce indoor Covid-19 transmission

The research focused on the 'upper-room' UV germicidal irradiation (UVGI) method of disinfection, which uses lighting units that emit UV-C light to create an irradiation field above people’s heads This allows for the disinfection of air – inactivating microorganisms by destroying nucleic acids and disrupting their DNA – while keeping people in the room safe from the harmful high-frequency light.

The researchers tested the feasibility of UVGI to reduce Covid-19 transmission by analysing historical published data examining the effect of UV irradiation on coronaviruses. They found that airborne SARS-CoV-2 virus particles are likely to be susceptible to UVC, and that the levels of light required to inactivate the virus would be practical and safe for upper-room UVGI.

SARS-CoV-2 particles are transmitted between people in various ways, including through aerosolised droplets. There is particularly high risk of airborne transmission in poorly ventilated spaces such as on public transport and windowless rooms.

“Now we know that Covid-19 infection can occur from airborne exposure to the virus, finding ways to minimise the risk of transmission, particularly in buildings, is becoming increasingly important,” said Professor Clive Beggs, an applied physiology expert at Leeds Beckett university. “Whilst we know wearing masks and opening windows are effective ways to minimise the spread of Covid-19 indoors, these measures aren’t always practical, especially in winter.

“Upper-room UVGI is already a well established technology and has proven effective to prevent the spread of other diseases such as measles and tuberculosis within buildings. This study shows that we have good reason to believe this technology could also protect indoor spaces such as offices, or restaurants and bars, and help to allow us to start the return to 'normal' life in a safe way.”

Queen Mary’s Dr Eldad Avital added: “Now it becomes more of an engineering problem of how we can use this technique to prevent the spread in buildings. This is where computational fluid dynamics becomes important as it can start to address questions around how many UVGI lights are needed and where they should be used. One thing we know is particularly important for these systems is air movement, so for them to work effectively in poorly ventilated spaces, you might need to use ceiling fans or other devices to ensure that larger aerosol particles are adequately irradiated.”

Next, the researchers will focus on exploring how UVGI could be applied in practice to reduce Covid-19 transmission, including by pairing it with a low-cost air purifier system to 'disinfect' air: “The idea is that air could be taken out of the room using an air purifier and disinfected with UV-C light, before the 'clean' air is then put back into the room,” Avital said.