Himalayan salt lamps purify air, meaning that they attract water molecules from the surrounding environment then absorb those molecules – as well as any foreign particles they may be carrying – into the salt crystal. As the HPS lamp warms up from the heat produced by the light bulb inside, that same water then evaporates back into the air and the trapped particles of dust, pollen, smoke, etc remain locked in the salt. small only 1.5 to 2 kg