Fire tokens are placed on a room’s name and affect every investigator and monster in the room. The effects are as follows:

An investigator or monster figure in the room at the end of its owner’s turn is dealt 2 damage.

An investigator must test his Willpower in order to enter the room. If he fails, he takes 1 horror.

Regardless of the result, he may then enter the room. Once in the room, the investigator does  not  need to test his Willpower to move to a different space in the same room.