IndusClassic® LGM-08 Rectangular Salt Lamp when warms, it attracts humidity and the surface of the salt crystal becomes damp. Negative ions build up and then released. Crystal salt lamps bind the excessive positive ions with their negative ions. The ions cleanse the air of harmful elector smog and other toxins. Known as Nature's Ionizers. Salt Crystal Lamps eliminate a host of indoor air pollutants. Natural salt has been exposed to massive pressure for millions of years, it has resulted in the formation of this durable crystal salt. The more pressure on the crystal salt, the stronger its composition. This is why salt crystal lamps will not reduce in size, color, shape, or their ionizing effect.