Personal Protective Equipment and Self-Contained Breathing Apparatus No. 3 Questions taken from Jones & Bartlett Fundamentals of Fire Fighter Skills (3rd Edition) Progress Indicator: Question 2 of 22 2.  Preshift examinations must be conducted within __________ preceding the beginning of any ___________ interval during which any person is scheduled to work or travel underground. Choices: 4 hours, 12-hour 3 hours, 12-hour 3 hours, 8-hour 4 hours, 8-hour