Just so we're all on the same page, damage for standing (not moving) on a surface is applied the moment a character's turn begins, before any action from that character is taken. So, it's not possible to avoid damage by moving out of the impacted area quickly. Whether you clear the affected area within that turn or not, the damage has already been taken.
Actually it's just a tiny bit more complex than that. The damage from standing on a surface happens in exactly 1 round increments. As such, if you began standing on that during another character's turn (ie: They made the hazard) then the standing damage will happen when the character who made the hazard's turn starts.
That is to say if turn order is T-U-V-W-X-Y-Z and X creates a fire surface on top of T then T will not take fire damage at the start of their turn. If T chooses not to move they will take fire damage at the start of X's turn instead.
Because of this if you have a jump skill you can actually get out of a hazard zone before it lands a second tick on you. Just so long as it being under your feet was caused by another character.
