The effect of UV light on inactivating the Coronavirus
This article tried to give more information about coronavirus and its causes. The rest of this article pointed at the suggestions to inactivate the coronavirus with UV light. In this review, the applicability of UV disinfection from the perspective of the COVID-19 pandemic was explained. This article predictably could generate a great deal of interest among researchers and industry on developing and manufacturing new viable UV air and surface treatment devices for current and future epidemics
As the incidence of COVID-19 spreading too fast in the whole world, the World Health Organization (WHO) provided some solutions on prevention and control strategies, such as the implementation of precautions against droplets, contact, and airborne transmission, aerosol-generating procedures, and support treatments of COVID-19. In order to ensure the safety of healthcare workers and contain the virus spreading, strategies have been developed to extend the lifespan of medical equipment as well as disinfect environmental surfaces . Some of the strategies are for decontaminating N95 and SN95 respirators and other stuff related to healthiness that going to be explained in future articles. What is clear these days is that just staying home and using a mask is not enough to prevent the spread of COVID-19. So new and innovative disinfection methods, including ultraviolet light, have attracted a lot of attention.
What is Coronavirus?
Coronaviruses are a large family of viruses that can cause illness, they can cause at least the common cold. in more critical situations other diseases like the Middle East Respiratory Syndrome (MERS-CoV) or the Severe Acute Respiratory Syndrome (SARS-CoV) .
COVID-19 has a range of symptoms that includes fever, fatigue, dry cough, aches, and hard breathing to acute respiratory distress and possibly death. It has also been reported that many infected individuals remain asymptomatic, which has complicated public health efforts to contain the spread of the virus .
Figure 1: UV radiation length 
What are the basic techniques to prevent the spreading of viruses?
The risk of spreading viruses can be controlled through many techniques, like heat sterilization, chemical disinfectants, filtration, and ultraviolet (UV) irradiation. The material damage could be caused by heat sterilization, in addition to the shortages of consumer chemical disinfectants and filters on the market, poses a critical challenge throughout pandemics leading to try to use more sustainable disinfection systems.Rapidly using UV radiation has been a fast-growing chemical-free technology over the past decades. UV radiation is highly efficient at controlling microbial growth in different media, such as water and air, as well as on any type of surface. There are three types of UV wavelengths that range from 100 nanometers to 400 nanometers (Figure 1). A particular spectrum of UV radiation between 100 and 290 nm called the UVC spectrum .
VC radiation is a known disinfectant for air, water, and nonporous surfaces. UVC radiation has effectively been used for decades to reduce the spread of bacteria, such as tuberculosis . For this reason, UVC lamps are often called “germicidal” lamps. UVC radiation has been shown to destroy the outer protein coating of the SARS-Coronavirus, which is a different virus from the current SARS-CoV-2 virus. The destruction ultimately leads to inactivation of the viruses. So UVC radiation may also be effective in inactivating the SARS-CoV-2 virus .
Over the UVC range, a more detrimental effect on microbial cells occurs because the intercellular components of microbes (e.g., RNA, DNA, and proteins) can sensitively absorb UVC photons and their genomic system could be damaged. The adenine−thymine bond is collapsed and a covalent linkage, pyrimidine dimer, is generated between two thymine leading to an inability of the cell to replicate (figure2) . UVB and UVC light can both interact directly with DNA in this way. This is the mechanism for UVC’s germicidal action, but at lower intensities, instead of lethal DNA destruction, lesions can turn into mutations. The body reacts to this kind of damage by killing and shedding damaged skin cells in the form of sunburn . Therefore, the effect of UV irradiation on microorganisms is called “inactivation” and not “killing”. In addition, many mutations will not have any discernible effect on the virus, as they are repaired by the host nucleic acid repair mechanism. The majority of the mutations diminish the infectivity of the viruses since most viral genes have a specific role to perform. However, some mutations may lead to the evolution of more pathogenic viruses. It is also likely that some UV-resistant strains of viruses will emerge. Different UVC sources have been utilized in academic research.
Figure 2: collapsing of adenine-thymine bond with VU radiation and generating thymine-thymine bond 
2) . UVB and UVC light can both interact directly with DNA in this way. This is the mechanism for UVC’s germicidal action, but at lower intensities, instead of lethal DNA destruction, lesions can turn into mutations. The body reacts to this kind of damage by killing and shedding damaged skin cells in the form of sunburn .
Therefore, the effect of UV irradiation on microorganisms is called “inactivation” and not “killing”. In addition, many mutations will not have any discernible effect on the virus, as they are repaired by the host nucleic acid repair mechanism. The majority of the mutations diminish the infectivity of the viruses since most viral genes have a specific role to perform. However, some mutations may lead to the evolution of more pathogenic viruses. It is also likely that some UV-resistant strains of viruses will emerge. Different UVC sources have been utilized in academic research.
The genomic structure and chemistry of a virus are critical factors in determining how the pathogen responses to UV radiation. Therefore, the UV disinfection kinetics of a novel virus, such as SARS-CoV-2, can be extracted from data available for a similarly structured pathogen , so chemists can reach the information about SARS-CoV-2 and may lead them to find a way to inactivate SARS-CoV-2.
In the absence of accurate UV inactivation kinetics for SARS-CoV-2, the previously established data could be utilized to estimate the required UV dose to inactivate the novel strain of coronavirus. SARS-CoV-2 is very similar to previous SARS-CoV-1 in terms. 600 microorganisms were studied under various UV radiation sources in different media (water, air, and surfaces). In addition, the Coronavirus family has been extensively studied and their response to UVC radiation is well-established. The Coronavirus family shows slightly more resistance to UV compared to commonly studied bacteria. On the other hand, a few studies observed more resistant behavior for SARS-CoV-1, suggesting higher UV dosage requirements. Over the last few months, a significant number of technical reports, news, and whitepapers have been released, claiming the effect of various UV disinfection systems and different UV lengths on SARS-CoV-2 . A list of recent articles about SARS-CoV-2.
inactivation and some other microorganisms with UV are gathered in Table 1.
Table 1:A list of information about CoV Inactivation Studies which are Recently Published 
Future of UV in COVID-19
The final goal of designing a UV disinfection system is to provide a robust product with reliable and reproducible performance. In this regard, the performance of any product must be validated prior to the introduction to the market. While obtaining the reported UV doses for SARS-CoV-2 inactivation is not challenging (by extending the exposure time), the development of UV disinfection devices to deliver the required dose consistently and uniformly urges design considerations and extensive validation through well-established protocols.
Due to the high use of UVC, it can be inferred that people tend to use this technology more, and in the absence of approved protocols and guidelines for the approval of UV disinfection products, many disinfection devices are based on Ultraviolet radiation with unknown effects against SARS-CoV-2 and measured immunity has caused concern .
1-Nogueira, Marcelo Saito. “Ultraviolet-based biophotonic technologies for control and prevention of COVID-19, SARS, and related disorders.” Photodiagnosis and Photodynamic Therapy (2020).
2- Raeiszadeh, Milad, and Babak Adeli. “A Critical Review on Ultraviolet Disinfection Systems against COVID-19 Outbreak: Applicability, Validation, and Safety Considerations.” ACS Photonics (2020).
3- Keil, Shawn D., et al. “Inactivation of severe acute respiratory syndrome coronavirus 2 in plasma and platelet products using a riboflavin and ultraviolet light‐based photochemical treatment.” Vox Sanguinis (2020)
4- Degradation of DNA in Whole Blood by UV Radiation at Varying Time Lengths of Exposure in website www.uncfsu.edu
5- Mamahlodi, Marang Tebogo. “Potential benefits and harms of the use of UV radiation in the transmission of tuberculosis in South African health facilities.” Journal of public health in Africa 10.1 (2019)
6- UV Lights and Lamps: Ultraviolet-C Radiation, Disinfection, and Coronavirus on website HTTPS:// www.fda.gov (August 2020)
7- Far-Ultraviolet Light in Public Spaces to Fight Pandemic is a Good Idea but Premature in website https://www.lesswrong.com (April 2020)
8- Patterson, Edward I., et al. “Methods of inactivation of SARS-CoV-2 for downstream biological assays.” The Journal of infectious diseases 222.9 (2020): 1462-1467.
9- Inagaki, H.; Saito, A.; Sugiyama, H.; Okabayashi, T.; Fujimoto, S. Rapid Inactivation of SARS-CoV-2 with Deep-UV LED Irradiation. Emerging Microbes Infect. 2020, 9, 1744.
10- Bianco, Andrea, et al. “UV-C irradiation is highly effective in inactivating and inhibiting SARSCoV-2 replication.” Inactivating and Inhibiting SARS-CoV-2 Replication (June 5, 2020) (2020).
11- Simmons, Sarah, et al. “Disinfection effect of pulsed xenon ultraviolet irradiation on SARS-CoV-2 and implications for environmental risk of COVID-19 transmission.” medRxiv (2020).
12- Manuela, Buonanno, et al. “Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses.” Scientific Reports (Nature Publisher Group) 10.1 (2020).
13- Pendyala, Brahmaiah, et al. “Genomic Modeling as an Approach to Identify Surrogates for Use in Experimental Validation of SARS-CoV-2 and HuNoV Inactivation by UV-C Treatment.”