Broad-spectrum of UVC light having a wavelength range of 200 to 400 mm can be effectively used for killing bacteria and viruses. Prolonged use of 254nm is hazardous for human beings, but is used to kill viruses and bacteria in germicidal applications. Exposure 254 nm can cause skin damage and eye damage which can potentially lead to skin cancer, photo keratitis, and skin aging.
Research conducted by Brenner et al. (2017) provides solid evidence that UVC light effectively kills H1N1 influenza, SARs, MRSA (Methicillin-resistant staphylococcus aureus) without harming human skin with the 222nm wavelength. The mechanism is based on destroying the molecular bonds that hold DNA together. Only a limited range of wavelength can kill the virus without causing damage to human skin. The 222nm range of Far UVC light is unable to penetrate through the outer dead cell layer of the human body therefore less harm is expected. In another research conducted by Welch et al. (2008) killing aerosolized influenza virus in the air was observed by far UVC light . Use of low doses of 222 nm far UVC light by a control group researcher killed flu virus H1N1 effectively.
Researchers from all these experimental works concluded that use of Far UVC can efficiently inactive the viruses at a low dose of 2 mJ/cm2 of 222 nm light. It can inactivate more than 95% of the H1N1 influenza virus. The researchers concluded that continues use of low dose rate UVC light for indoor public locations is a promising, low cost, safe and compatible technique to reduce the spread of diseases due to virus.
If we confirm this case in some other situations, it can be illustrated that the use of low powered far UVC light even in public places can be represented as safe and more useful way for limiting the transmission and spread of those microbial diseases that are airborne like influenza or Tb.
Figure : Quantification of the antiviral efficacy of 222-nm far-UVC light
It is known that the potential of using UV light for disinfecting the airborne pathogens are not new in use and this technique of using UV light to kill or deactivate the microorganisms was discovered almost 80 years ago. Airborne ultra violet germicidal irradiation (UVGI) can be used through conventional germicidal UVC light by applying on upper area of the room, avoiding the direct exposure to the occupied areas of the room. Talking about the advantages, a clear benefit of using UVC base approach other than the vaccination approach is that the UVC light is effective against almost all kinds of the microbes in air.
For example, for different influenza strains, vaccinations do not always address the variation, however UVC inactivation efficiency is certain. In short, we have explained that with very low doses of far UVC light can inactivate the airborne viruses very efficiently.