My experience. When hiking with a buddy, we talk A LOT, catching up. If he is in the lead, then he stirs up dust and as I'm blabbing I'm also inhaling a lot of fine trail dust.
At the end of the day, do you find that you have black dirty booger mucus in your nose?
it dries up the throat, coats it with trail dust, mouth is open, talking a lot, the friction irritates and inflames the throat. It's not an infection, but the dryness and friction could strip away the slime that coats the throat, which usually protects.
I also notice that when I'm in the lead, and my buddy is following, no inhaled dust for me. Throat is fine.
Solution is to:
1) keep your mouth closed or wear a bank robber bandana over your mouth.
2) talk less
3) don't follow the trail dust too close
4) if you must follow close and talk, then regularly take tiny sips, gargle, to rinse the throat dust accumulation.