We don't have any dust problems yet. This is a new coop with a concrete floor and a pea gravel run. We've only had our 2 pullets for a week. The 10 week old buff orpington pullet has had an intermittent cough or sneeze since the day we got her. Likely a little sick when we got her, but the seller is not near us. Runny eyes / nose got worse after a couple of days, but are now better.
At this point we are just trying to feed them well, give them access to the yard and bugs and generally keep them happy which they seem to be. The cough / sneeze and occasional raspiness is still about the same.