ionizers are good at removing smell, but they can fuck up plants, and you, if you over use them. i have a pretty powerful one, and it runs for one minute at a time, 6 times a day. that pretty much kills any odor in my house before it can build up, and it also helps kill anything like mold that's in the air.
if you over use it, it will start to fuck up younger plants, then move on to fucking up the larger ones, burning leaves like light burn. it will eventually cause you respiratory distress, bleeding sinuses, that kind of thing. they're good, and i wouldn't be without mine, but only use one as much as you need, this is one case where more is not better