Abstract: There is provided an NBC protection and decontamination system, including an enclosure, an airlock, an airlock compartment, having a ceiling, and including a back-flow collector, an air filtration unit, a compartment inlet valve communicating with the air outlet of the enclosure, an exit valve being provided in the compartment and spaced apart from the compartment inlet valve, and an opening providing controllable passage between the enclosure and the airlock, and an opening providing controllable passage between the airlock and the outside, wherein the airlock compartment is swept by two different airflows, a first airflow originating in the enclosure and a second airflow produced by the filtration unit.