Fig. 2From: Comparing and optimizing ultraviolet germicidal irradiation systems use for patient room terminal disinfection: an exploratory study using radiometry and commercial test cardsPower and Energy Output of the Small UVGI Units. a The power output in time is expressed in mW/cm2 for each distance. b The curves show the cumulative energy (in mJ/cm2) at each distance for each device. A power of 1 watt (W) applied for 1 second (s) produces 1 joule (J) of energy. The green line represents the C. difficile lethal energy dose (38.5 mJ). 5 feet = 1.5 m; 8 feet = 2.4 mBack to article page