Which Door To Safety?

You are trapped in a room with three doors, and the power is out completely. You have to pick a door and escape, but all the doors have hazards on the other sides. The first room is a small vent made of pure metal, and has lots of fire on the outside, making the metal super hot. The second is a large dome filled with water that is electrical, meaning you will be electrocuted, and the third is filled with poison gas. Which door leads you to safety?