re: Can anyone recommend a good air purifier for my house?

Given how serious this is for you, have you considered having an indoor air quality (IAQ) assessment conducted on your home? You didn’t mention this in your post so I’m assuming you haven’t had this done.

A reputable independent firm/individual that can perform the assessment and interpret the results for you, but at the same time is not trying to sell you a particular equipment product, but might be able recommend equipment/devices based on the results. Easier to address the problem, if you can identify the potential cause(s).

I don’t have anyone I can recommend as I’ve never had to do this but perhaps other posters might.

Maybe some articles like these can assist

LINK

LINK