The dust is mostly from the chicks’ bodies as their feathers growing in. I’m sure some is from the feed and shavings but chicks are just dusty little things no matter what you do. More bedding, adding a new thin layer daily, even twice daily, can help trap the dust in the bedding so it doesn’t get kicked up so much from their activity. I typically change out the bedding when the smell gets more noticeable but that all depending on how many chicks are in there and how big the brooder is.
The best way to deal with it is brooding outside or in a garage. I’ve taken to keeping chicks inside for maybe the first 2 weeks then kicking them out to the larger brooder in the shed/garage.