A study conducted by a team of researchers from Columbia University in New York has revealed that far-ultraviolet C (UVC) light inactivated more than 99% of an airborne virus in an occupied work environment,

Unlike conventional germicidal UVC light — which kills viruses and bacteria but can only typically be used in unoccupied rooms because direct exposure to it can potentially harm skin and eyes — far-UVC light can be used in occupied spaces.

Overhead lamps emitting far-UVC (222-nm) light were employed to reduce levels of an airborne virus in an occupied room. Source: David Welch, Columbia University Irving Medical Center

This is possible, according to the researchers, because far-UVC light has a shorter wavelength (222 nm) than germicidal UVC light and thus cannot penetrate or damage living skin or eyes.

Studies conducted at Columbia University labs showed that far-UVC could quickly and efficiently inactivate airborne pathogens in small and room-sized test chambers.

Specifically, the team set out to demonstrate that far-UVC light could be used in an occupied room where high levels of a harmless virus were present.

To accomplish this, the researchers chose a room where laboratory mouse cages were cleaned to test the far-UVC light. The researchers selected this location because the majority of mice carry a type of norovirus that doesn't make animals or humans sick. However, when the cages are cleaned, high concentrations of this harmless virus become airborne.

As such, the team installed four overhead far-UVC lamps in the cage cleaning room and subsequently collected daily air samples to measure infectious virus levels on days when the lamps were turned on against the infectious virus levels on those days when the lamps were turned off.

Based on these tests, the researchers discovered a reduction in infectious airborne viruses of around 99.8% — which is reportedly far more achievable than using air filtration and ventilation.

The research is detailed in the article, "222 nm far-UVC light markedly reduces the level of infectious airborne virus in an occupied room," which appears in the journal Scientific Reports.