Legal and Ethical Principles of Emergency Care Test No. 2 Questions taken from Chapter 2 of Emergency Medical Responder - First on Scene (9th Edition) Progress Indicator: Question 2 of 12 2.  When sampling using a CPDM, the person certified in sampling must monitor the dust concentrations and the sampling status conditions being reported by the sampling device ______ or more frequently as specified in the approved mine ventilation plan. Choices: at the end of the cut between the 1st and 2nd hour of the shift at mid-shift during the last hour of the shift