Wat ben ik?

From the box (translated from Dutch): I am a person but I don't know who. What must I ask before I know? A bag? No. A hat? And do I have something in my hand? Am I wearing something blue? Am I in the countryside? Am I the pilot? The cook? No, I must be the fireman! But I must be sure before I look. Which question shall I ask to get the right clue. Hurray! I've found it. Everything points out that I must be the nurse!