Critical Design Parameters in Design and Efficacy of Upper‐Room UVC(254) Luminaire Systems: Part I: Overview of Major Parameters and Relationships

Jensen, Paul Arthur

During the current SARS‐CoV‐2 and tuberculosis global pandemics, public health and infection prevention and control professionals wrestle with cost‐effective means to control airborne transmission. One technology recommended by Centers for Disease Control and Prevention and the World Health Organization for lowering indoor concentration of these and other microorganisms and viruses is upper‐room ultraviolet 254 nm (UVC(254)) systems. Applying both a material balance as well as some nondimensional parameters developed by Rudnick and First, the impact of several critical parameters and their effect on the fraction of microorganisms surviving UVC(254) exposure was evaluated. Vertical airspeed showed a large impact at velocities <0.05 m s(−1) but a lesser effect at velocities >0.05 m s(−1). In addition, the efficacy of any upper‐room UVC system is influenced greatly by the mean room fluence rate as opposed to a simple volume‐ or area‐based dosing criteria. An alternative UVC(254) dosing strategy was developed based on the fluence rate as a function of the UVC(254) luminaire output (W) and the square root of the product of the room volume and the ceiling height.