Himalayan crystal salt lamps.

Salt Lamps sold as ionisers.

Whenever you see Himalayan salt lamps for sale they’re almost always promoted as negative ionisers. The truth is, although they might be attractive as lamps, compared with the performance and output of a modern electronic ionizer, they are not particularly effective at ionising air.


So what are these ionising crystal salt lamps and where do they come from?

Ionising salt lamps, crystal salt lamps, Himalayan salt lamps – they’re really all the same thing – carved chunks of naturally formed sodium chloride (or common salt) from underground mines.

Millions of years ago, when ancient seas and salt lakes slowly evaporated, they left behind thick deposits of what geologists call Halite. Literally translated this means Rock Salt (from the Greek halos, meaning “salt” and lithos meaning “rock.”)

Rock salt is found in sedimentary rock on all continents around the world. And mining it is big business.

Common uses for Rock Salt are:

Cooking – you will see it sold in your supermarket as a table or cooking salt.
Dissolved in water as industrial brine – used to manufacture chemicals like chlorine, caustic soda, fertilisers and many other substances. http://www.mineralco.net/salt/industrial-salt.php
Mixed with grit for spreading on roads in icy weather.

But where other minerals have leached into it, the salt bed is often stained with various fascinating tints and colours. It seems that someone had the bright idea (forgive the pun) of carving this material into lamps.

And how does a salt lamp produce negative ions.

They say the ionisation is from evaporation of water when the lamp is warmed.

So the carved salt draws moisture from the surrounding air then, when you switch the lamp on, the absorbed moisture evaporates again, generating negative ions in the process.

We all know how standard table salt attracts moisture from the air – notice how quickly it clogs in damp weather? Well, salt lamps are carved from larger pieces of the same material. They very easily absorb moisture from the room. (In fact, so readily that manufacturers recommend you regularly use the lamp or, in a particularly damp atmosphere, cover it with a plastic bag to stop it actually dissolving.)

It’s true that evaporating water does produce a modest amount of negative ions. But would that be enough to make it an effective room ionizer?

We’ve been searching for some solid technical data regarding the negative ion output and range for these lamps. But all the information we’ve found so far seems very vague and “alternative” – quoting “energy vibrations” and “crystal frequencies” etc. – with no real scientific facts or figures.


You must use a filament bulb – one that gets quite warm (not an economy lamp), otherwise the water won’t evaporate and dry out the salt. So they are not very energy efficient.

The rate of evaporation (and therefore the “negative ionizer” effect) is variable – dependant on the humidity of the room. (It’s like trying to dry washing, dry days are better, damp days slow things down).

After the lamp has been on a while, all its moisture will have evaporated, so no more negative ions. You’ll need to switch off and wait for it to get damp again.

Also the amount of water held in the salt lamp is pretty small. For instance, compare it to drying a few damp clothes on a radiator, or blow-drying your hair – you’ll get lots more evaporation. The principle is the same but you wouldn’t consider those as ionisers. Even your breath evaporates quite a lot of moisture (try breathing out hard on a frosty day and see the steam) so you already have your own in-built personal “ionizer”.

Many people use ionisers in their bedroom for a restful sleep – but it’s rather difficult to sleep with a lamp on all night.

So, in conclusion, if you want a salt lamp, that’s fine. But don’t expect it to perform anything like a genuine purpose-built negative air ionizer.

These people (suppliers) say it quite well: http://www.naturalsaltcrystallamps.com/how-salt-lamps-work.html

“The salt crystal lamps have a similar effect to the ionizer. However, the natural ionization of a crystal lamp cannot be compared to an ionizer.”

“Here however it is pointed out that the emission of ions by heated salt crystal lamps, should not be regarded as the primary characteristic, because from scientific standpoint, the surplus of negative ions is negligible.”

Here is a short extract from Wikipedia: http://en.wikipedia.org/wiki/Himalayan_salt

“Himalayan salt is a marketing term for rock salt from Pakistan, which began being sold by various companies in Europe, North America, and Australia in the early 21st century. It is mined in the Khewra Salt Mines, the second largest salt mine in the world, located in Khewra, Jhelum District, Punjab, Pakistan, about 300 km from the Himalayas, about 160 kilometres from Islamabad, and 260 kilometres from Lahore, and in the foothills of the Salt Range.

The salt sometimes comes out in a reddish or pink color, with some crystals having an off-white to transparent color. It is commonly used for cooking similar to regular table salt, brine, and bath products. Generally, Himalayan salt is used for culinary purposes in the same way as ordinary table salt. It is also used as a bath-salt.”

Astrid  High Output  Ionisers  - only available  at the  Astrid Ioniser Store