Holy Shit! A science-based post! THANK YOU THANK YOU THANK YOU!!!!From Wiki:
The 'ions' referred to are in fact charged oxygen or nitrogen molecules surrounded by a cluster of water molecules, rather than ions. Scientific studies have shown no particular benefit from a greater concentration of negative ions.
I can see no scientific reason why this would help a plant at all, it's just a matter of making humans feel better. Ozone generators however, kill pathogens in the air but may burn plants if not vented correctly. Ozone generators can also be used to get rid of smells, but activated carbon is a better bet.