## 1 Introduction  
COVID-19, a disease caused by SARS-CoV-2, has caused a serious pandemic that necessitated significant scientific, economic, and public efforts to control the threat [1, 2, 3, 4]. The most effective way to halt the pandemic is to prevent the spread by disrupting the viral transmission routes. Pathogens, such as viruses, can transmit and spread through the atmosphere or contact with a contaminated surface. Many methodological approaches, such as heat sterilization, chemical disinfectant, ventilation, and ultraviolet (UV) irradiation can help to reduce the risk of viral infection [5]. Over the last few decades, UV-based disinfection has become a common chemical-free technology [6]. UV radiation is extremely effective at disinfecting bacteria in various mediums, such as water, air, and an object's surface [7]. UVC light air and surface disinfection have attracted considerable attention, and several products have been released in the market since the COVID-19 pandemic began. UV surface disinfection systems have been implemented in a wide range of public places, including hospitals and health care institutions, as well as restaurants and cafeterias [8]. However, a lack of understanding of the critical features of UV disinfection has resulted in an inappropriate use of this formidable platform, not only by the general public, but also by some UV surface disinfection manufacturers. UV light occurs in a multitude of forms, each of which is classified according to the amount of energy it possesses. UVA light is the one with the least amount of energy and is less effective at inactivating SARS viruses than UVB or UVC radiation [9]. UVB light, located in the center of the UV spectrum, is known to damage DNA and is related to the development of skin cancer and cataracts. UVC light is the most powerful and effective form of UV light for disinfecting surfaces, air, and liquids since it has the highest energy. The UVC light can be effectively absorbed by the biomolecules, i.e., nucleic acid or proteins, leading to the generation of photoproducts that inactivate the viruses, hence it is very effective in disinfecting surfaces, air, and liquids. UVC light causes nucleic acids and proteins to break down, which kills germs including viruses and bacteria [5]. The reason why UV radiation is effective in disinfection is because it has enough energy to break DNA chemical bonds. UVC light, which has a wavelength range of 260 nm to 275 nm, damages the genetic information stored in DNA, rendering dangerous microbes like bacteria and viruses ineffective. Pathogens such as viruses and bacteria also require DNA and RNA to survive, and without this genetic material, these pathogens are unable to replicate, leading to the death of an infectious colony. Since the intercellular components of bacteria, such as RNA, DNA, and proteins can sensitively absorb UVC photons, the UVC range has a greater adverse effect on microbial cells. UVC photons that are absorbed cause significant damage to microorganisms' genomic systems, such as nucleic acid and microorganism proteins, preventing them from replicating and surviving. This is due to the collapse of the adenine-thymine bond, which results in the formation of a covalent linkage, the pyrimidine dimer, between two adenines, preventing the cell from replicating. UVC light has been used to destroy a significant amount of SARS-CoV-2 in liquid culture after 9 min of exposure [10]. Another study used far-UV light radiation to disinfect SARS-CoV-2 surface contamination and found that 222 nm UVC light reduced the viable SARS-CoV-2 by 99.7% in 30 s [11]. Far-UVC light also killed 99.9% of airborne human common cold coronaviruses, 229E and OC43, in around 25 min [12]. A variety of UVC sources have been employed, including low and medium pressure mercury UV lamps, UV light-emitting diodes (UV-LEDs), and far-UVC (200-240 nm) radiating excimer and micro plasma lamps [13; 14; 15].