F/cc is the unit used to express what in asbestos fiber measurements?

• A. Fibers Per Cubic Centimeter of air
• B. Fiber Count Per Cubic Centimeter
• C. Fibers per Cubic Centimeter
• D. Fiber Per Cubic Centimeter of Air

Answer: (A)

F/cc measures how many asbestos fibers are in each cubic centimeter of air. In practice, an air sample is drawn through a filter for a known volume of air, the fibers are counted under a microscope, and the fibers counted are divided by the actual air volume sampled to give fibers per cubic centimeter of air. This direct focus on the breathing-zone air concentration is why the unit explicitly specifies “of air”—it distinguishes airborne concentration from fibers in a solid sample or on a surface. The concept is that exposure risk depends on how densely packed fibers are in the air a worker breathes, not on the total fibers present in a bulk material. As you work with samples, remember that increasing the sampled air volume while keeping the fiber count the same lowers the f/cc value, and increasing the fiber count raises it.