Cape Town - Using advanced light technology to sanitise the air and public spaces of airborne viruses, including Sars-CoV-2, is being touted as a possible way to curb the spread of pandemics.
While social distancing and sanitising your hands remain the main line of defence for the spread of Covid-19, ultraviolet light is also being used at malls and airports overseas.
Columbia University physicist Dr David Brenner has been at the forefront of developing this light technology for everyday use.
Ultraviolet C (UVC) has wavelengths of 200-280 nanometres and is blocked by the ozone layer when it emitted from the sun so it’s harsh rays never reach the earth’s atmosphere, unlike those of UVB.
In a recent public TED Talk, Brenner said: “Over the past six years, we have applied this idea in working towards a safe way to kill drug-resistant bacteria such as MRSA (methicillin-resistant Staphylococcus aureus), as well as airborne viruses such as influenza, using a unique type of ultra-violet light.
“In brief, it is pure physics - 222nm light is safe for us because it cannot even penetrate through the dead-cell layer on the surface of our skin or the tear layer on the surface of our eyes, but because bacteria and viruses are physically very small, 222nm light does have enough penetration to efficiently kill them.”
FAR UVC Africa is a Johannesburg based company that has 15 products available for purchase that uses this UVC technology.
The company’s managing director, Conrad Kullmann, said: “We have small light products, 20W, that you can use in buses, taxis and public transport, right up to units that you can use as gateways ... we do sanitation tunnels but with human-safe FAR UVC light.
“The 150W light covers 60m² square meters and at 2.5m it kills Covid-19 in the air and on surfaces in nine minutes. The closer you get to the light the quicker the sanitation happens.”
The director of the Laser Research Institute at the Physics Department at the University of Stellenbosch, Dr Pieter Neethling, is a lot more cautious about the use of UVC.
Neethling said: “The idea behind using UV sterilisation and disinfection actually comes from the late 1800s. The Nobel Prize for it was given in 1903 so it’s not a new concept. What is new, however, is that the lighting technologies have improved so these days.”
Neethling said in order to kill viruses you would need a stronger UVC, and prolonged use is not advisable. “It affects the DNA or the RNA of the microbe (UVC targets), so the virus absorbs this radiation and essentially undergoes a chemical reaction which immobilises the virus. If you go outside and lie in the sun you won’t get lots of UVC, but mostly UVB. UVC is just more dangerous and it is very much dosage dependent. If you spend a long time (in UVC) then it would be dangerous; if it’s just a short time it would be okay. In my opinion, this is not something I would think is necessary.
Neethling says there are uses for light technology in sanitation. “Mercury lamps have been available for a very long time and are used in laboratories which sterilise their environment. Mercury is harmful and that is where the LEDs come in and that is a relatively new innovation.”
But the team at FAR UVC Africa believe they have a safe product that can be rolled out quickly and is effective in the fight against airborne diseases.
Kullman said: “All the testing has been done on it, we have all the white papers on it, to prove the efficacy of it. All of our products are what you call the filtered FAR UVC which makes it 100% safe for humans, animals, plants. It doesn’t even penetrate the dead layer of your skin.”
Weekend Argus