A Technician BA-N2 (Breathing Apparatus/Nitrogen Level 2) primarily works in oil & gas/refinery settings, performing maintenance on specialized safety gear (BA sets, gas monitors) and ensuring safe confined space entry (vessels, tanks) during shutdowns, using nitrogen purging and monitoring atmospheres for hazardous gases, requiring strict adherence to HSE/PTW/LOTO procedures, and needing valid certifications for confined space, rescue, and BA equipment.