can a block of salt really clean the air?
October 22, 2009 3:24 PM   Subscribe

Will my new Himalayan salt block lamp really clean the air?

For a living room night light, I bought a small lamp that consists of a seven or eight pound block of translucent pinkish-orange salt that was mined from deep underground in the foothills of the Himalayas. It sits on a wood base and is lit by a small candelabra bulb which is inserted in a space hollowed out from the bottom. These lamps are sold by various internet outlets, with various claims of beneficial properties. I don't put much credence in the more fantastic sales points I read while shopping for the best price, such as it eradicating "destructive negative energy" put out by computers and other electronics, or the that because the mineral deposit formed 250 million years ago when the earth was all pure and clean means it will cast positive feng shui over the living space.

I do wonder, though, about the assertion that when heated by the light bulb, the salt will attract and then split water molecules in the air and thus release negative ions that will bond with positively charged particles of various pollutants in the air and cause them to drop out of the air and give the room the same freshness that you notice outside following a thunderstorm. Will this lamp really purify the air to any degree? Is there any truth to that?
posted by longsleeves to Home & Garden (15 answers total) 3 users marked this as a favorite
posted by dfriedman at 3:43 PM on October 22, 2009 [9 favorites]

So its like a prehistoric Ionic Breeze?
posted by ian1977 at 3:49 PM on October 22, 2009 [1 favorite]

My wife has a salt block light so I'm curious about this too. I think a better angle on this is (1) whether the rock does in fact emit any negative ions, (2) whether the quantity is actually significant, and (3) whether these ions are healthy. #3 is debatable, but #1 and #2 should be answerable by basic chemistry. I'm looking for answers right now but so far I'm just turning up a lot of unsubstantiated snake oil.
posted by crapmatic at 3:50 PM on October 22, 2009

according to this rather mystical website, it does this:

Research proves that heated salt crystal lamps are natural ion generators. They bind the negative ions with excess positive ions ( that are produced by electrical appliances and computers). When the lamps become warm, they absorb moisture and the surface crystals become damp. This builds up the ion field.

What is the effect of this reaction? The ambient air surrounding the lamp is cleaned by the transformation cycle of hydrogen and oxygen, as well as sodium and chloride ions. The resulting purified air is helpful in the relief of asthma symptoms and upper respiratory problems.

I'm skeptical about the science behind this. I'm also skeptical about the deep-Himalayan origins of your piece, as I've seen these on all manner of street corner displays
posted by Think_Long at 3:57 PM on October 22, 2009

Response by poster: crapmatic: a better angle on this...

Um, that's pretty much exactly what I'm asking here, but thanks for the input!
posted by longsleeves at 4:04 PM on October 22, 2009

If it really ionized the salt it would slowly turn into a lump of sodium (bad!) and release pure chlorine gas in the process (also bad!). So let's hope it's not true.
posted by GuyZero at 4:04 PM on October 22, 2009 [10 favorites]

Response by poster: Think_long: It came from a salt mine somewhere, we know that much.
posted by longsleeves at 4:08 PM on October 22, 2009

This link may be helpful in explaining why this claim is bullshit.
posted by dfriedman at 4:13 PM on October 22, 2009

More debunking here. They look nice though.
posted by Behemoth at 4:31 PM on October 22, 2009

You can get house plants that will clean your air.
posted by low affect at 4:35 PM on October 22, 2009 [1 favorite]

Response by poster: (all defensive now)
It really was purchased just for its pretty night light aspect, (for $25); air quality isn't a big concern. Thanks for all comments so far.
posted by longsleeves at 4:54 PM on October 22, 2009

No. It might suck moisture out of the air, as salts tend to do, which would make the air a little drier. It would also slowly dissolve as a result.
posted by chairface at 5:23 PM on October 22, 2009

Best answer: Any substance will produce ions if you get it hot enough, so somewhere way down there there is some vestige of truth to this. But you're not getting any ions to speak of at night light temperatures and I've yet to hear a solid reason why they'd make your life better anyway.

The pretty nightlight aspect is definitely the quality to consider here.
posted by Kid Charlemagne at 5:25 PM on October 22, 2009

No, but it will be pretty and your cats/dogs/visitors will enjoy licking it. (I have a salt lamp)
posted by cuddles.mcsnuggy at 7:50 PM on October 22, 2009

chairface: No. It might suck moisture out of the air, as salts tend to do, which would make the air a little drier. It would also slowly dissolve as a result.

Only until it absorbs enough water to reach an equilibrium state (which won't take long). This is analogous to the way most people superstitiously put air-dry packets into their luggage, closets, etc. Once exposed to the open air, they absorb all the water they're ever going to in a matter of hours, and are no more effective dehumidifiers than a spoon (unless redried for several hours in a rather hot oven).

It would also slowly dissolve as a result.

Dissolve into what solvent? It won't dissolve, evaporate, or otherwise sublimate.

It could decrease in size due to pet licking, however.
posted by IAmBroom at 8:11 AM on October 23, 2009 [1 favorite]

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