Look up the PMS7003, I think I got it for $40 bucks on aliexpress and it's used in many air filters to monitor PM2.5 and PM10 etc sized particles. Easily run by a raspi and i output to a regular segmented display for my particle counts averaged every 5 minutes to see the california fires and how quickly my air filter could clear the room. For reference the winix 545 ($110 from costco iirc) on full blast got me down to about 0 particles in 15 minutes.

edit: oh and regarding fan noise, the PMS7003 has a tiny centrifugal fan in it but I can barely hear it with my ear on top of it. The winix air filter on full blast though... crazy loud compared to the other low/med/high settings it's kind of hilarious how big of a jump it is in fan speed