Fire Down is an item appearing in most Bomberman games. It decreases the player's max blast radius by 1. In grid-based Bomberman games, this means the player's bomb explosion will decrease by one tile. In many free-area Bomberman games, this decreases the spherical blast radius by a certain amount.
Typically, it is best to avoid the Fire Down item. A possible exception may be situations in which a smaller blast radius would make puzzle-solving easier. For example, in Bomberman 64: The Second Attack, the Ice Bomb is used to cross gaps of liquid. A small explosion may make it easier for the player to keep kicking bombs into the water or lava while standing on a small platform.
Also, Fire Downs can also be a good item. Sometimes, when placing bombs with a high fire range, it may be hard to avoid the flames, so collect a few Fire Downs and think before getting a Fire Up.