Here is my rock lamp and its accompanying positive ions. I don't know what positive ions in the air are good for; I haven't even bothered to look it up. I don't even care, because I like my salt rock lamp regardless of any airborne benefits.
However, I just got a tiny humidifier with a face and a hat. It doesn't work (or maybe I just don't understand the highly translated instructions) so I must sadly return it, regardless of its awesome face and hat--on account of its lack of airborne benefits.