Protection Factor (PF) is defined as the ratio of what?

Protection Factor (PF) is defined as the ratio of what?

• A. Inside concentration divided by outside concentration
• B. Outside concentration divided by inside concentration
• C. The difference between outside and inside concentrations
• D. The square root of outside concentration

Answer: (B)

Protection Factor shows how well a protective measure reduces exposure by comparing what’s present outside to what ends up inside the protected space or breathing zone. It is defined as the outside concentration divided by the inside concentration. For example, if the outside concentration is 1000 units and the inside concentration is 1 unit, the PF is 1000, meaning the protection reduces exposure by a factor of 1000. Taking the inside concentration divided by the outside concentration would invert this meaning, giving a value that doesn’t reflect the protection level. The difference between outside and inside concentrations isn’t a ratio that conveys protection, and taking the square root of the outside concentration isn’t a meaningful definition for PF.

Protection Factor shows how well a protective measure reduces exposure by comparing what’s present outside to what ends up inside the protected space or breathing zone. It is defined as the outside concentration divided by the inside concentration.

For example, if the outside concentration is 1000 units and the inside concentration is 1 unit, the PF is 1000, meaning the protection reduces exposure by a factor of 1000.

Taking the inside concentration divided by the outside concentration would invert this meaning, giving a value that doesn’t reflect the protection level. The difference between outside and inside concentrations isn’t a ratio that conveys protection, and taking the square root of the outside concentration isn’t a meaningful definition for PF.