Earlier advancements in nanotechnology have brought to the development of photocatalysts, which offer hope in the regulation of infectious microorganisms through advanced disinfection methods. This study reports the antimicrobial efficiency of photocatalysts in a general office indoor and in a hospital scenario. The antimicrobial efficacy of visible light based photocatalytic devices was tested against bacteria from air and various surfaces from three rooms, one on each ground floor, first floor and second floor in the Indian Medical Association (IMA) premises before the installation of the devices and at intervals of 24, 48 and 168 hours after the installation. Another similar study was conducted by IMA in National Heart Institute (NHI) to test the photocatalyst efficacy in a hospital scenario. In NHI three locations were selected for this study, isolation room in Intensive Critical Care Unit (ICCU) 3, deluxe room 205, washroom of deluxe room 205. Sterile conditions were recorded following the installation, which proved beyond reasonable doubt that photocatalytic devices were capable of excellent disinfection.