Also called "biologically inert" dusts and "particulates not otherwise
classified" (PNOC), the lung-tissue reaction caused by nuisance dusts
is characterized by
1) Air space architecture remaining intact.
2) Collagen (scar tissue) not forming to a significant extent.
3) Tissue reaction is potentially reversible.
The ACGIH* recommends a TLV of 10 mg/m3 for this dust
(containing no asbestos and <1% crystalline silica).
*ACGIH: American Conference of Governmental and Industrial
Hygienists is an organization that recommends Threshold Limit
Values (TLVs) for chemical and physical agents in the workplace.