Bench Talk

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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 UV’s 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.

UVA, UVB, and UVC—each classified according to their wavelength and energy—are the three main types of UV, a form of electromagnetic radiation. UVC—which has the shortest wavelength and highest energy—is the only UV able to “kill” microorganisms, including viruses and bacteria. According to the International Ultraviolet Association, a dose of 40mJ/cm² of 254nm UVC light kills 99.9 percent of “any pathogenic microorganism” by damaging their DNA, protein, and RNA structures.

This discovery in the early 1900s led to artificially produced UVC—or Ultraviolet Germicidal Irradiation (UVGI)—becoming a common disinfection solution. Used for sterilizing water, air, and nonporous surfaces in hospitals, laboratories, and more, it reduced the spread of many diseases, including SARS CoV in the early 2000s. UVC saved thousands—if not millions—of people from serious illness and death. So, why isn’t UVC already a frontrunner in the fight against Covid-19?

Most experts agree high-intensity UVC 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 UVC 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 UVC 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 UVC light can cause textiles, plastics, or polymers to degrade.

While research shows UVC 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.

Fortunately, there are several ways UVC has already been safely applied in public areas to help protect against Covid-19.

• Automation Systems: One example is the use of UVC in building automation systems, such as its security system. In this scenario, the automation system schedules UVC beams to operate when people aren’t around, and—with the use of motion sensors—immediately shuts down when they are. Automation 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.

• Air Purification Systems: Air handling systems also provide an opportunity to indirectly beam UVC away from people. According to Signify and Dr. Anthony Griffiths, an associate professor at Boston University School of Medicine UV, UVC radiation can potentially reduce the SARS-CoV-2 virus on surfaces by over 99 percent within less than a minute by applying a dose of 22mJ/cm².

• Handheld or Mobile Devices: A number of manually controlled handheld and mobile UVC emitting devices have also come to market, and have already been snapped up by a number of Hollywood Studios desperate to resume film and TV production.

• Far UVC: A filtered UVC 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.

While widely agreed that UVC light won’t fully replace a mop and bucket any time soon, there’s no denying its vast potential in the fight against Covid-19, or the fact that it complements chemical disinfectants by targeting germs in a different way. With further advances that help UV LEDs reach their full potential—in terms of efficiency, reliability, and lifetime—and technologies, such as IoT and 5G smart lighting, it’s reasonable to predict that automatic disinfection could play a big role in helping us overcome Covid-19 in 2021, and, hopefully ensuring, it’s a far more positive year for all.

The Can Covid-19 Really be Fought with UV Light? blog was written by John Hauschild and was first published on https://www.henkel-adhesives.com/.