To give credit where credit is due,
@Daniel, I read it from you, "If you're not wearing a filter, you are the filter.
Dead trees and thick bark are very dusty, as are, to a lesser degree, green trees. Stump cuts and walking/ working atop powdery, dry soil in the latter half of summer can contribute lots of particulates to the air. Milling and backpack blowing, too.
@Steve Connally recommended RZ masks, shown in pic.
I like mine, but less than the cheaper, vented masks that I got through Amazon...5 masks for about $20. I've the ear is way easier on and off while working than RZ masks with 2 elastic straps with buckles.
The small buckle beneath the helmet straps is OK, but not ideal.
Helmets need to be removed to put on and take off the RZ ('don' and 'doff', for the language lovers).