Investigation of the effect of red light, blue light and red and blue light combination on the disinfection process by UVC

Abstract

     Ultraviolet radiation (UV), especially UVC radiation (200-280) nm, has a strong bactericidal effect by directly destroying their DNA structure. UVC not only influences microbial cells but also damages human and other animal cells after exposure. To reduce the dosage of UVC radiation and limit its harmful effects, we investigated the impact of blue LED light (460 nm) and red LED light (630 nm) and the combination of red and blue LED light (red-blue) on the disinfection process by UVC LED light (253 nm). This study shows that Staphylococcus aureus was more sensitive to UVC than Escherichia coli. The irradiation of red-blue lights followed by UVC treatment exhibited a strong effect on S. aureus in the saline solution; however, this effect was not observed for E. coli. On the agar plate, the combination of red-blue increased the bactericidal efficacy of UVC light on both S. aureus and E. coli whereas blue light only enhanced UVC efficiency on E. coli.