Black walnut dust, is it the same as ground walnut shells?...
Nope, the black walnut dust I get exposed to is from sanding the wood. I sometimes make furniture and do other woodworking projects, and I get exposed to the dust when I sand a project or turn things on the lathe. It's always good to wear a respirator when there's any kind of wood dust in the air, but I HAVE to wear one religiously and open the windows for lots of fresh air whenever I work with black walnut.
We also use ground walnut shells to polish the antique sleigh bells I restore for people. The shells are from English walnuts, not black walnuts. The ground up shells that I have are particles about the size of fine kitty litter. They are a wee bit dusty, but I'm not sensitive to it like I am to black walnut. They're not really the same thing at all.
"...Wow, that's a strong FO!!!! Apples and pine would actually smell really good LOL..."
It is really super strong. I bought it knowing I couldn't use it in soap (I forget why -- it's been awhile), but I thought it might be nice for an air freshener or similar thing. I agree -- a pine or fir EO would blend nicely with this FO.