For thousands of years salt from the Himalayan Salt Mines has been know for its healing powers. Those with asthma, bronchitis, and other respiratory issues would be sent to live in the salt chambers of the mountain as a cure for their ailment.
Salt lamps create negative ions which attach themselves to positives ones (the bad ones) consequently making them very heavy. They then fall to the ground or a surface in your home as dust that is then easily vacuumed or dusted. Available in various sizes.