Aim: No study has systematically captured the perceived threat, discomfort or issues experienced by First Responders (FRs). We aimed to report the FRs’ experience during a mission for an out-of-hospital cardiac arrest (OHCA) in a ten-year span. Methods: We collected all the 40-items questionnaires filled out by the FRs dispatched in Ticino Region (Switzerland) from 01/10/2010 to 31/12/2020. We compared results between FRs alerted by SMS or APP and between professional and citizen FRs. Results: 3391 FRs filled the questionnaire. The OHCA information was considered complete more frequently by FRs alerted by APP (85.6% vs 76.8%, p