Gilbert gave a link to a gal who sells beeswax candles and asserts they clean the air.
The mechanism, she says, is
Beeswax releases negative ions when it burns. Pollen, dust, dirt, pollutants, and any other junk in the air all carry a positive charge, and that is how they can be suspended in the air. The negative ions released from burning beeswax negate the positive charge of air contaminants, and the neutralized ions are sucked back into the burning candle or fall to the ground. Many air purifiers and water filters harness this effective negative ion technology.
Seems convincing enough, but it struck me as an odd assertion. Now, I'm no chemist, so maybe it common for a chemical reaction like combustion to have an electrical result like ionization.
I tried to do a little homework.
Googling "beeswax burns negative ions" gives lots and lots of results from people with beeswax to sell. I don't see anything else, except people with the same question as me.
Ya I market beeswax products and I would love to set the record straight on the negative ions thing. I have heard that it emits air cleansing positive ions or that the beeswax ions neutralize ions released by electronics. I also heard that burning beeswax emits a spectrum identical to that of the sun. Please set the record straight. I have had an unsatisfactory time searching for the answers.
A search for "allergen positive charge" gives similar results, but it did at least bring up a WebMD article.
The article is very informal, and WebMD ain't exactly Johns Hopkins, but I'll give them several pegs more respect than random productsellers! The article says researchers saw some benefits from exposing people to negative ions generated by a BIG ionizer. They recommend against household (electrical) ionizers as being too small and weak.
(Hey, this search actually appears to have been the right way to find it.)
You have exactly the same claims made about himalayan salt lamps (see here), though as a mineral I'm more inclined to believe that.
The main ref in that article is also the WebMD - there are some other references are the bottom which may lead somewhere (but for me it'll have to wait till after work):
Thayer, R.E. (1989). Biopsychology of Mood and Arousal. New York: Oxford University Press
Diamond, M. (1988 ) Enriching Heredity: The Impact of the Environment on the Anatomy of the Brain. New York: Free Press.
Yepsen, R.B., Jr. (1987) How to Boost Your Brain Power: Achieving Peak Intelligence, Memory and Creativity. Emmaus, Pa.: Rodale.webmd.com/balance/features/negative-ions-create-positive-vibes