Media fill media - aerobic/anaerobic condition

can anyone tell me which are the conditions that need to perform an aseptic process simulation using a media as THG (for anaerobic conditions) instead of TSB (aerobic condition)? is there a specific requirement? i.e. if the firm performs the filling operations under nitrogen but the quantity of residual oxigen in the vial is about 2%, can I consider that an anaerobic condition?
thank you for your replies