I'm having minor breathing issues and suspect the home air quality, which seems to be excessively full of particles/dust. The air quality is visually noticeable daily, regardless of basic cleaning/outside air steps take the day before.
Background: I bought the home last fall, it was a DIY 1700sq ft remodel built in CO in 1980 and the home inspection found nothing substantively wrong. It has central air - electric single unit AC/Heat Pump.
Just before the winter I had the attic insulated and sealed with cellulose. A short while later I started noticing the breathing issues and dust in the air. There is no HVAC in the attic, and it started getting cold around the installation time, so perhaps it's just a misleading coincidence.
I have replaced the HVAC filter several times and use one of the higher quality HEPA filters (rated for smoke particles). I had a company come in and clean the ducts. I have vacuumed, dusted, and had all the windows open on days 65F+ to circulate new air in, without engaging the HVAC system more than a couple of times. The picture is less than 24 hours after such a complete clean and open window day and shows the density of particles in the morning sun.
Couple of edits from comments - I have basic home air filters in the basement and in the master bedroom and I leave a humidifier on in the kitchen area constantly (definitely a hard water area though). House is still low though... about 34% humidity in the basement. No one smokes in the home, and I moved about three miles... my last place I never recall seeing the air quality so low (gas central air in a studio)!
What can I do to identify and fix the excessive dust/air quality? Are there tools, a likely suspect, or a professional service that I need to source?