are not only bad for you, but they are ineffective. I knew from the first time that a parent brought the flyer for one of those in. Ozone is known to decrease lung function and trigger asthma, so producing it in your own home can't be a good idea, but they don't work very well either:
The magazine found that five of the six ionizing cleaners don't clean
very well. "They were all ineffective in removing pollen, dust and smoke from
air," says Jeff Asher, the magazine's technical director.
In general, the data on any type of air purifier having a signficant effect on allergies is low. Individual studies have generally shown no signficant effect, but a metaanalysis did show some benefit.
Overall, I don't generally recommend them, but I am not against them either, if the family wants to spend the money. I do think money and effort are better directed at specific allergens such as dust mites or pollens.