Abstract: A breath sampling device has a body defining an interior space or bore with two open ends. The patient's breath is directed through the device from end to end, thereby continually purging the interior space. At a designated time during the breath, closure devices are actuated to shut both ends, desirably in response to a single actuation movement, thereby capturing a breath sample at a predetermined time. The continual purging action assures that the captured breath sample truly represents the breath at the designated time during the exhalation cycle.