Which is the concentration unit used in this method?

• A. F/L
• B. F/cc
• C. F/mL
• D. F/μL

Answer: (B)

In this method, concentration is expressed as fibers per unit volume of air. Counting how many fibers appear in a known volume of air drawn through a filter and then dividing by that air volume gives the result in fibers per cubic centimeter (f/cc). This unit is standard for airborne fiber measurements because it directly relates the number of fibers to the amount of air a person is exposed to, and it aligns with exposure standards that are based on fibers per cubic centimeter. Per liter or per microliter would apply to liquids or extremely small volumes, which isn’t the typical context for counting airborne fibers, and fibers per cubic meter (f/m3) is another acceptable expression but in this specific method the unit used is f/cc.