A figure developed by the American Conference of Governmental Industrial Hygienists intended to represent the maximum level of airborne contaminants that will cause no adverse effects, even after prolonged exposure; a concentration of airborne material that experts agree can be inhaled for a working lifetime by almost all workers without any injury. The few workers who will be affected will develop their symptoms so slowly that periodic medical examinations can be expected to detect them while the effects are still reversible. While permissible exposure limits
are legally binding limits, required by OSHA, TLVs are recommended limits.