The ASTM method establishes the time to breakthrough under conditions of continuous liquid or gaseous contact. The default breakthrough time is 480 minutes (eight hours). A lot of companies choose clothing materials that offer the eight hours of breakthrough time - which represents a worst-case scenario - when the exposure situation may only require, say, four hours. By properly assessing the resistance of protective clothing materials to permeation, employers can effectively downgrade and still get optimum protection.
|Jennifer Mathes, Ph.D.|