Himalayan Salt Lamps are made of edible salt from the Himalayan Mountains in Pakistan. If it does't come from this region, the lamps are reported to have no therapeutic effect.
Note : What is written below is relevant only to genuine salt lamps; and only if the lamp is turned on / heated.
So, what do salt lamps do? Their pros and cons ....?
The Western View - Ion Pespective
Salt lamps generate negative (-) ions. This is a good thing. (-) ions increase the frequency of the space surrounding it. This makes a space feel lighter because the increase in frequency reacts subtly on brain neurology, lowering the autonomic nervous system, and calming the human body.
It also generates fresh air (clean air). (-) ions increase oxygen flow to the brain, allowing the body to feel more alert. And because it makes you feel alert but lowers the autonomic nervous system, you feel positively energetic but not hyper-vigilant and panicky.
Leaving a bottle of water or anything organic next to a salt lamp will increase the (-) ion strength of it. You'll be consuming food and drink with enhanced energy.
Hygroscopic - As it attracts water, it draws in impurities that get trapped in the moisture in the air. This moisture gets released back into the air via evaporation but the impurities remain 'stuck' to the lamp. This means the air surrounding the lamp (about 10 feet for a small lamp) tends to be low in allergens.
Note : Wiping your lamp with a damp cloth once a week is necessary to keeping the lamp clean.
If you see salt deposits and moisture accruing around your salt lamp, especially the base, you know you've got the genuine thing. Your lamp is doing its work.
The Eastern View - Feng Shui Perspective
As salt attracts water, it dries up the space. This can be drying for skin ... etc. And this creates a lethargic environment.
However, salt is considered energy neutralising. In this respect, it is a welcome addition into the home. In fact, if you are buying 2nd hand jewellery, you can either place it next to a salt lamp for a few days or better yet, wash it with genuine Himalayan Salt water to neutralise its energy form the previous owner.
As our homes have more and more electrostatic energy from mobile and electronic devices. I feel the pros from the Western perspective far out weigh the cons from the Eastern perspective. A genuine salt lamp in Singapore will set you back between SGD$30 - $80. Not an expensive investment. And even if you don't think it works ... they sure are pretty to have around.