Amongst the deluge of sanitisation solutions that have flooded the market during the pandemic, UVC-based devices have stood the tests of time, efficacy and safety. However, many are still apprehensive about the effects of UV on human beings, and may be hesitant to adopt it. Dilip Patil, Managing Partner, Trivector Biomed LLP used his biomedical degree to simplify the science of a specific wavelength of UVC, how it differs from other wavelengths and how it should be used for sanitisation.
Is there a ‘bad’ UV and a ‘good’ UV?
The UV radiation spectrum is divided into three regions: UVA (315-400nm), UVB (280-315nm) and UVC (100-280nm). UVC is further subdivided into Far-UVC (200-230nm).
All UV is good as far as its exposure is controlled. UVA and UVB, and to a certain extent UVC, can penetrate into the deeper layers of the skin and eyes and contribute to skin ageing, wrinkling and may cause skin cancer and eye damage, if uncontrolled.
UVC (especially at 254nm wavelength) has been used for over seven decades for disinfecting water, surfaces and air. However, this germicidal UV cannot be used in occupied spaces when people are around, as it is carcinogenic and harmful to the skin and eyes.
However, Far-UVC at 222nm is just as effective as 254nm UVGI (Ultra Violet Germicidal Irradiation) but is 100% safe as it does not penetrate the outer layer of the skin or the tear layer of the eyes. Hence, it is safe to use for air and surface disinfection when people are around.
Filtered 222nm Far-UVC’s safety and efficacy are well established. Far-UVC devices have been tested on live SARS-CoV-2 and were found to be effective upto 99.99% within a few minutes.
How does Far-UVC work at the cellular level?
The conventional 254nm UVC inactivates pathogens by damaging DNA/RNA in the nucleic acid of pathogens by forming a dimer. On the other hand, 222nm Far-UVC not only damages the DNA/RNA in the nucleic acid, but also has an additional kill mechanism of breaking peptide bonds in the outer protein coating of single cell microbes and cells.
What is the difference in the design of traditional UV lamps and Far-UVC lights?
Traditional UVC lamps are arc lamps and use mercury vapours in a glass enclosure, while Far-UVC lamps are mercury-free and use Krypton Chlorine inside a quartz enclosure. Additional band-pass optical filter is used to suppress unwanted secondary wavelengths in Far-UVC lamps. They don’t emit ozone.
This is the only technology that is able to quickly disinfect air and surfaces of occupied spaces in real time.
How should each of your solutions be used in their respective environments?
Eco Cab devices can be easily mounted in a cab, ambulance or bus with a magnetic attachment. These 20W lights can be plugged in 12/24V car/bus cigarette lighter sockets or can be hard-wired.
Luminaires (Lights) are for ceiling mounting of the devices, either pendant (high ceiling), wall mount or flush mount. They are mounted the same way as our routine lamps and are plug and use. They come in 150W and 20W options.
Hand sanitation sensor-based devices are for liquid-less, alcohol-free dry all-round hand sanitisation within 10 seconds.
Sanitisation gateway looks like a metal detector walk-in frame, and contains 7x150W lamps (motion sensor based FAR UVC-lights) to give full body sanitisation within 10 seconds. It can be installed at the entry points of busy commercial spaces like malls, office complexes and theatres etc.
Mobile unit for the hospitality/healthcare sector. Used for quick room sanitisation in between two consecutive occupancies.
Speedpoint POS units for sanitisation of speed points (cash-points) within 1.5 minutes.
What is the contact time needed for eliminating microbes?
The closer you are to the Far-UVC device, the quicker it disinfects. e.g. The Far-UVC hand sanitiser unit kills pathogens in 10 seconds, while ceiling/floor devices kill in 9 minutes at 2500 mm distance from the source of infection. A typical ceiling mounted Far-UVC light could disinfect a room of volume up to 5000 cubic feet within nine minutes.
Should such solutions be used 24×7 or intermittently?
Unlike routinely used UVC lamps which need to be switched off when somebody moves around, Far-UVC devices are switched on automatically on human movement. They can be used 24×7, but considering their rapid deactivation of microbes at the point of contamination, they need not be kept on all the time.
All Far-UVC devices supplied by us have PIR motion sensors which activate when there is movement and remain active for 15 minutes after the room has been vacated. We call this ‘connect and forget’ utility. There are cab and portable devices which can be manually switched on or off safely, depending on the requirement.
Using this method, what is the average cost of sanitisation?
The one-time cost is obviously more than mercury-based conventional UV lamps. The average life of Far-UVC Excimer Lamps is about 4000 hours of continual use. Yet, the cost of ownership per square metre, taking into account that the lamp will last for a year, will be less than 10 rupees (i.e. less than a rupee per square foot).