Resumen: The strategic aim of communication in cases of Public Health crisis is to approximate, as far as possible, the perception of risk by the society and the situation of real risk, in order to reduce the anxiety about the crisis by evidence based information, according to the seriousness of the Public Health alert. The citizen’s perception of risk is a legitimate reality that we must accept and learn to manage better. We present a case study of the Public Health Alert System (PHAS), which aims to ensure the control of Public Health alerts in the Aragon region outside normal working hours. Therefore, along with the activities carried out in the normal working hours, the alerts are attended to 24 hours a day for the entire year. The PHAS is designed to meet all the urgent situations (confirmed or suspected) that may affect the collective health of the population. Idioma: Inglés DOI: 10.29199/GEEH.101011 Año: 2017 Publicado en: Journal of global epidemiology and environmental health. 1, 1 (2017), 46-53 ISSN: 2637-7144 Tipo y forma: Artículo (Versión definitiva) Área (Departamento): Área Medic.Prevent.Salud Públ. (Dpto. Microb.Med.Pr.,Sal.Públ.)