Whole-Room Disinfection Using Germicidal Light

The electromagnetic spectrum includes ultraviolet (UV) light, which has a wavelength of 100 to 400 nanometers (nm), and visible light, which has a wavelength of 400 to 760 nm.² “The UV spectrum from 200 nm to 400 nm, as well as visible light up to a wavelength of 405 nm, are considered to be germicidal,” said Arthur Kreitenberg, MD, clinical professor and orthopedic surgeon, University of California Irvine, and cofounder and chief technology officer, Dimer LLC, Los Angeles, California. The germicidal light most commonly used for disinfection is UVC, which has wavelengths of 220 to 280 nm.^{3, 4} Ultraviolet light can inactivate microorganisms by degrading their genetic material and reducing their ability to reproduce.³ Visible light works by targeting intracellular porphyrins that absorb the light and produce reactive oxygen species that kill bacteria.⁵

According to Kreitenberg, when used for disinfection in health care settings, germicidal light only works “line of sight” and does not reflect off equipment, walls, or ceilings or penetrate clear glass. “Its efficacy drops off extremely quickly with distance from the light to the target surface,” he said. “It has limited ability to penetrate a biofilm, so routine mechanical cleaning remains a mainstay.” AORN indicates that room decontamination systems can be assessed for use as an adjunct to manual cleaning protocols to help decrease contamination on surfaces in the OR that could lead to transmission and patient infection.⁶ “Reducing surface bioburden should reduce surgical site infection risk; however, the problem is that multiple studies show that EVS [Environmental Services] crews miss about 50% of potentially contaminated surfaces,” Kreitenberg noted.