Many industries today rely heavily on the detection system to be fast enough and give such early warning that the rescue service arrives in time to extinguish the fire before the damage is severe. In some cases they also trust that the detection system gives such early warning that the smoke does not cause any damage like smell and corrosion on the goods stored. However, it is not easy to detect smoke at an early stage in premises with high ceiling heights, as the smoke from a small fire is insufficiently thermally buoyant to reach right up into the ceiling zone.