An air purifier is a good addition to a kids bedroom.

I got one during Santa Cruz wildfires in 2020 and now the kids have a pavlovian reflex to sleep once that gets turned on.

Ikea makes an air-purifier table, which is a end-run around it being a useless box in the room when switched off.

It's fairly expensive, not as good as a purpose built one, but it blends into the average room pretty well.