Abstract: A modulator transportable collective protection system for the decontamination and containment of personnel in a toxic free area. A contamination containment area is provided through which personnel are decontaminated prior to entering the toxic free area. The migration of contaminants is prevented by causing a purge of clean filtered air from the toxic free area to the contamination control area and to the exterior environment. A blower and filter unit provides air to the toxic free area to maintain an over pressure therein, ensuring that all entry to the toxic free area is through a flow of clean air.