EE WAS WORKING AT A ROOF REHABILITATION JOB SITE AT THE APPROACHES TO VENT. SEALS, WHEN THEY ENCOUNTERED AN AREA WITH LOW O2 LEVELS. EE BENT OVER TO ASSIST ANOTHER EE WHEN HE WAS OVERCOME AND BECAME UNCONCIOUS. HE WAS REMOVED FROM THE 02 DEPRIVED AREA AND IMMEDIATELY RE-GAINED CONSCIOUS.