I have similar - well, not with the “scream mode”, but an air purifier with the UV light inside. Have another HEPA downstairs that I don’t use. Bought both a few years back when we had the fires.
I love mine but the replacement hepa filters alone cost almost as much as building this box. I have to take the pre-filter out a lot and wash it. Seventy-year-old houses accumulate a lot of dust out in the country over the years! I also have small portable hepa filter units in two of the bedrooms.
The guy that designed this box is as good with duct tape as any mountain hillbilly I ever met. 😁