If you read the advertisings or informercials of vendors or dealers of Aranizers, they will say the air purifier is good for asthma sufferers.

That machine produces "activated oxygen" which is heavy oxygen (O₃) or also called ozone. While producing ozone, the negative ions can also help charge up particles in the air and make them cling to the surfaces of other material like walls of buildings or walls of the boxes of air purifier.

Heavy oxygen can kill mold, and neutralize certain gasses to rid of smell but it has other health side effect.

To read on ozone, click or pasted the following government link to your browser.

http://www.epa.gov/iaq/pubs/ozonegen.html#is%20there%20such%20a%20thing%20as%20good%20and%20bad%20ozone

In the article it says: "in the process, the reaction (of ozone) produced a variety of aldehydes, and the total concentration of organic chemicals in the air increased rather than decreased after the introduction of ozone (Weschler, et. al., 1992b). In addition to aldehydes, ozone may also increase indoor concentrations of formic acid (Zhang and Lioy, 1994), both of which can irritate the lungs if produced in sufficient amounts."

Note:

Aldehydes are volatile organic compound (VOC). When we buy paint for our house we want non VOC paint or very low VOC paint because VOC  is bad for the lungs.

Formiic acid is a colorless caustic fuming liquid, used in dyeing and finishing textiles and paper and in the manufacture of fumigants, insecticides, and refrigerants. (source: Columbia encyclopedia).