Technician Team Exam - Drager BG4 Taken from the 2018 National Mine Rescue Contest held in Lexington, Kentucky Progress Indicator: Question 1 of 30 1.  The breathing air is circulated in a open breathing cycle.  The carbon dioxide contained in the exhaled air is absorbed in a regeneration cartridge (CO2 absorber).  The breathing air is enriched with oxygen from the oxygen cylinder. Choices: True False