Abstract: A decontamination system in combination with a work space maintained at subambient pressure. An inner vestibule is connected to the work space via a first portal, which can be selectively opened and closed by a first door. A middle vestibule, in which at least one shower bath is installed, is connected to the inner vestibule only via a second portal, which can be selectively closed by a second door or opened. An outer vestibule is connected to the middle vestibule only via a third portal, which can be selectively opened and closed by a third door, and to an ambient space only via a fourth portal, which can be selectively opened or closed by a fourth door. Each door is a rigid door. Except for the third door, which seals the third portal when the third portal is closed by the third door, each door has fixed louvers allowing small quantities of air to infiltrate.