Look at this post and the subsequent ones in the thread.
[forumosa.com/taiwan/viewtopic.ph … 701#110701](Dehumidifiers and air purifiers
The ionising function is commonly contained within an air cleaner which will also have a fan and a filter. They’re available at hypermarkets such as Carrefour and DIY shops such as B & Q. If you want to leave it switched on all night in your bedroom, you should do an internet search and form your own conclusion as to the health benefits or dangers.