Installation of a ultraviolet irradiation system, type C, plant and its influence on indoor air quality

We have investigated the effect of UVC on IAQ in a ventilation plant in a typical office building. The UVC-system consisted of UVC-lights for irradiation on all central components in the air handling unit. A similar ventilation plant, but without UVC, was chosen as a reference plant. Microorganisms on surfaces, living airborne mould spores and MVOC (Microbial Volatile Organic Compounds) were sampled throughout the ventilation plant and in corresponding rooms before and after UVC-irradiation. In addition, parallel measurements in the reference plant were conducted. The number of colony forming units on surfaces were reduced in the "UVC-plant" after irradiation. For living airborne mould spores and MVOCs, no significant difference was observed. Conclusive UVC-systems seems in general to have little effect on IAQ in buildings with normal comfort ventilation plants.