The employees, according to their professions, are exposed to different risks. Each employer must provide the necessary means adapted to the results of the prevention approach to rescue an injured person (article R. 4224-16 of the Labour Code). One of the means of possible action is the establishment of an alarm device for lone workers (DATI). This choice must, however, remain consistent with the result of the process of prevention and risk assessment. The employer who does not respect its obligations toward its workers may be held criminally liable.