Figure 3.

UVC irradiation for 240 s induces over 3.5 log reduction in SARS-CoV-2 viral titers. (A) Time course of log reduction of SARS-CoV-2 in N95 test coupons treated with UVC irradiation. N95 mask squares (2.5 cm²) with all layers were incubated with infection media spiked with SARS-CoV-2 for 15 min. The respirator coupons were then placed on open 10 cm polystyrene cell culture dishes 15.2 cm from the lamp. After warming up the lamp, the blocks were treated for the indicated amount of time per each side. Respirators were left in infection media at 4 °C overnight. One ml of the mask derived media mix was used from each condition and was titered in VERO-E6 cells using plaque assays targeting the SARS-CoV-2 Spike (S) and Nucleocapsid protein (NP). Each dot represents data from three independent experiments and plotted data bars represent mean and standard deviation for the triplicates. Vertical dashed line delineates untreated and treated parts of the experiment. Horizontal dotted line is the minimal level of detection (approximately 67 PFU ml⁻¹). Baseline for the assay is shown using a continuous line. (B) Regression analysis of viral reduction as per timely UVC irradiation.