One of the most popular commercial uses of ultraviolet light sources is for disinfection. UV light, especially UV-C (λ < 280 nm), has a germicidal effect on micro-organisms living in air, water, and on surfaces. It is lethal to viruses, bacteria, bacterial spores, mold, mold spores, yeast, and algae. UV light is also used in medical sanitation and sterilization of work facilities. High power UV-C LEDs are suitable as point of use source or may be integrated into systems for disinfection purposes.