There was a chap on here prior to Magnus who took over his biz.
Charlie, original provider, developed some very bizarre ailments from dust from grinding feather quills and handling the feathers constantly.
Not to say it's dangerous, I don't know enough about the issue or illness, but Magnus now promises us all he uses not a mask, but respirator. I hope so!
Just be careful while being frugal. Otherwise, Magnus will trade one wing for the other and return whichever wing is desired in ground full length feathers in exchange.
I believe he's still doing that! He's a sponsor here in Assoc Sponsor listings, so that is another option...but for all who do your own, just be careful!