Hi, There is a lot of literature about UVC and its sanitizing effects. In water is widely used to remove bacteria (also from Hiperpure water systems). In open spaces (air, surfaces) there are some studies but the effectiveness is a bit more complex to clarify. You will find some references here and some data as well irradiation levels to kill bacteria, viruses or fungi:
UV-C radiation (200- 280 nm) is very effective to disinfect water, air, and surfaces, while 265 nm is most effective due to the largest overlap with the absorption spectrum of the nucleo bases of DNA. However, the details are complicated, since the required dose (energy per area multiplied by the application period) is dependent on the inactivation rate of the specific mircroorganism, while the effective dose is dependent on many factors regarding the radiation source, i.e. spectral power distribution, peentration depth, flow rate. Appended you will find some slides to visualise this.