# Comparative Study of Blue Light with Ultraviolet (UVC) Radiation on Betacoronavirus 1
## 3 Results  
Dose-dependent inactivation of Betacoronavirus 1 without any external photosensitizer. The viral sample was exposed to 405 nm with a 17,280 mJ/cm\({}^{2}\) dose for 2 h and 40 min, and an inactivation of log\({}_{10}\) 2.84 was observed. For 222 nm, the virus sample was exposed to 3 mJ/cm\({}^{2}\) for 3.27 s, which resulted in a log\({}_{10}\) 2.50 reduction. For ultraviolet rays (i.e., 254 and 270/280 nm), a 10 mJ/cm\({}^{2}\) dose was exposed for 3.26 and 288.18 s, respectively, which resulted in a log\({}_{10}\) 3.17 and log\({}_{10}\) 3.37 reduction. The summarized results are shown in Table 1. The basic infectivity test was conducted on a 270/280 nm exposed sample, and a significant reduction could be observed in comparison to the control sample, as shown in Figure 5. This viral sample was randomly chosen to observe the light exposure's efficacy.  
Figure 4: Betacoronavirus 1 was plated in a 96-well plate and incubated for 16–24 h. An inverted microscope was used to count the number of wells with and without CPE, followed by calculating the TCID50 using the Reed–Muench method: (**a**) performing TCID50 on host cells in a 96-well plate; (**b**) using an inverted microscope to count the number of wells with and without CPE.  
Irradiation measurements at varying distances. The irradiances at varying distances from 10 to 50 cm were measured to draw a relationship using the inverse square law. Figure 6 shows the relationship between the irradiance and distance for the DIEHL blue light. The inverse square law was used to draw irradiance and the distance dependence assuming the constant angular position (\(\theta=0^{\circ}\)). From Figure 6, the curve equation can be used to calculate the intermittent irradiance value at different distances for the same blue light source used in this study. Based on the calculated irradiance and desired dose, the exposure time could be calculated using Equation (1). Table 2 shows the irradiance at varying distances for all of the different lights used in this study.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Light Source** & **Irradiance** & **Exposure** & **Dose** & **Log** & **\%** \\  & **(W/cm\({}^{2}\))** & **Time (s)** & **(m)/cm\({}^{2}\))** & **Reduction** & & \\ \hline
405 & \(1.80\times 10^{-3}\) & 9600 & 17,280 & 2.84 & 99.85\% \\
222 & \(9.18\times 10^{-4}\) & 3.27 & 3 & 2.50 & 99.68\% \\
254 & \(3.50\times 10^{-3}\) & 3.26 & 10 & 3.17 & 99.93\% \\
270/280 & \(3.47\times 10^{-5}\) & 288.18 & 10 & 3.34 & 99.95\% \\ \hline \hline \end{tabular}
\end{table}
Table 1: Showing the TCID50 results for the exposed virus sample, applied dose, and exposure time for different UVC radiation and blue light.  
Figure 5: The basic infectivity test result of the control sample, i.e., the viral sample not exposed to any UVC radiation or visible blue light and the viral sample exposed to UVC. (**a**) Control sample showing the infected plague of the virus. The control sample was kept at 4 \({}^{\circ}\)C at the testing facility. (**b**) Viral sample exposed to a 10 mJ/cm\({}^{2}\) dose of 270/280 nm, showing much less infected plague compared to the control sample.