I don't think negative ion generators are big at all. You can find little ones for not too much money.
Negative ion generators are not made for this application, and will quickly be overwhelmed.
Please don't try this. Please. This is not where you experiment, or try to save money, or try to do it a 'new' way. Smell will get you busted.
Smell will get you busted. Must not smell. Smell = jail. Don't.
And not trying to pick on you Sc, just wanted to take the opportunity to drive the point home.