Agreed. N95 mask or better.
What mix do you use, then?
I have gradually settled on an inorganic mix with four basic components.
1.Horticultural Pumice ( sifted for preferred particle size and specific use)
Ie: drainage, promoting root growth coarser or finer, cuttings, seed etc.
2. Black Lava ( sifted to remove fines)
3. Granite Grit ( sold as turkey grit called Cherry Stone)
4. Akadama ( harder, medium size particle, better quality)
Percentage of each component changes for specificle would be purpose as may the particle size.
For example for young aggressive pines, more grit for weight and stability with the grow box or container chosen. They can quickly extend and fill out becoming top heavy for lighter mixes.
Another example would be increasing the pumice for greater water retention and or lighter weight soil mix.
The black lava is a bit heavier than the pumice and a great color to darken the mix.
Note: because i use an inorganic soil mix, i use an organic fertilizer to promote microbial growth in the beginning. I also use a portion of the old soil to transfer other necessary micro-organisms.
The akadama is usually around 10% to 20 % of the overall.
The exception is for Azaela and then i prefer Kanuma to Akadama. Due to cost i limit the number of Azaela in my collection.
It is my belief that this approach gives my plants more years of uninterrupted growth and the components last way longer making them cost effective in the long run. The added benefit is trees that can be worked on more often and developed at a faster pace.