Can Covid-19 really be fought with UV light?

The use of ultraviolet (UV) LEDs for sterilization and disinfection is nothing new. But a hot topic for the lighting industry this year is the question of UVs effectiveness against Covid-19. While initial research has been positive, it’s shown that using UV to kill dangerous Covid-19 pathogens is not as simple as turning on a light switch.

Here’s why.

WHAT IS ULTRAVIOLET LIGHT?

There are three main types of UV, a form of electromagnetic radiation – UVA, UVB and UV-C – each classified according to their wavelength and energy. However, UV-C, which has the shortest wavelength and highest energy, is the only UV able to “kill” microorganisms, including viruses and bacteria, by damaging their DNA, protein and RNA structures (according to the International Ultraviolet Association, a dose of 40 mJ cm of 254 nm UV-C light kills 99.9% of “any pathogenic microorganism”).

This discovery in the early 1900s led to artificially produced UV-C – or Ultraviolet Germicidal Irradiation (UVGI) – becoming a common disinfection solution. Used for sterilising water, air and nonporous surfaces in hospitals, laboratories and more, it’s reduced the spread of many diseases, including SARS CoV in the early 2000s, and has saved thousands – if not millions – of people from serious illness and death.

So, why isn’t UV-C already a frontrunner in the fight against Covid-19?

UV VERSUS COVID-19

Most experts agree high-intensity UV-C can disinfect areas against Covid-19 and kill the SARS-CoV-2 strain quickly. However, there are limitations:

• The optimal length of exposure, wavelength and dose of UV-C light needed to kill SARS-CoV-2 varies depending on factors such as the shape and type of contaminated material.
• Covid-19 requires the highest exposure of UV-C of any virus tested, an amount that’s harmful to humans.
• It needs direct contact to work, meaning it’s less effective in an area in shadow or covered by dust.
• Prolonged exposure to such intensive UV-C light can cause textiles, plastics or polymers to degrade.

While research shows UV-C light is a feasible way to disinfect spaces, it also highlights the need for it to be carefully operated, adapted and scheduled to be effective in different scenarios, plus only used where no people are present. 

SAFELY IMPLEMENTING UV-C

Fortunately, there are a number of ways UV-C is already being safely applied in public areas to help protect against Covid-19.

Automation systems

Automations systems and services are a key investment and growth area for the lighting market leaders as they look to take advantage of connected and smart lighting and associated wireless internet and sensor integration. One of the clear benefits is the safe implementation of UV-C systems.

One option is the use of UV-C with the automation systems of a building, such as its security system, so that it’s scheduled to operate when people aren’t around, and – with the use of motion sensors – immediately shuts down when they are.

An example of this is Puro Disinfection Lighting, who create full ceiling and mobile spectrum UV disinfection fixtures. Their devices have already been installed in hospitals, schools and more, plus are currently being trialled on buses and subways in NYC.

Air purification systems

Air handling systems also provide an opportunity to indirectly beam UV-C away from people. Take electronic firm Dynamics recently launched Nanowave Air. A portable contraption, they claim it’s “the first device to inactivate the Covid-19 in fast moving air” by “sucking up germs and blasting them with high-intensity ultra-violet light”. According to Signify and Dr. Anthony Griffiths, an associate professor at Boston University School of MedicineUV, UV-C radiation can potentially reduce the SARS-CoV-2 virus on surfaces by over 99 % within less than a minute by applying a dose of 22mJ/c.

Handheld or mobile devices

A number of manually controlled handheld and mobile UV-C emitting devices have also come to market, such as the Xenex’s Lightstrike “germ-zapping” robots. Claiming to “deactivate 99.9% of coronavirus germs in two minutes”, they’re operated with a simple start button, and have already been snapped up by a number of Hollywood Studios desperate to resume film and TV production.

Far UVC

A filtered UV-C that operates at a frequency of 222nm, far-UVC isn’t considered harmful to humans, yet still powerful enough to kill Covid-19 pathogens. This means it can be deployed in areas with an increased risk of Covid-19 that are rarely empty, such as hospitals. Japanese light-maker Ushio Inc have already developed the far-UVC projecting, Care 222 UV lamp, “the first indoor cleaner in the world against Covid-19” (yours for a nifty $2,870).

LIGHTING THE FUTURE