In this paper some measures are presented of particle concentration and sizes, carried out in different wards of the Campus Bio-Medico University Hospital of Rome in the summer 2015. More specifically, some operating rooms (Day Surgery) have been taken into consideration together with the surgical block and the surrounding areas. Some experimental tests were carried out in the operating room in different simulated conditions of operation and with different particle counters. The results are related with different events (opening doors, switching on the operating light, movements of nurses and surgeons, etc.); attention is paid to different clothing of the staff.