Enter the concentration of a substance outside and inside a respirator to determine the Assigned Protection Factor (APF) of the respirator.

Assigned Protection Factor Formula

The following formula is used to calculate the Assigned Protection Factor (APF): 

APF = Concentration Outside / Concentration Inside

Variables:

  • APF is the Assigned Protection Factor, which indicates the level of protection provided by a respirator or mask.
  • Concentration Outside is the concentration of a substance in the air outside the respirator (ppm).
  • Concentration Inside is the concentration of the substance inside the respirator (ppm).

To calculate the APF, divide the concentration of the substance outside the respirator by the concentration inside the respirator.

What is an Assigned Protection Factor?

An Assigned Protection Factor (APF) is a rating that represents the level of respiratory protection that a respirator or mask can provide. It is the expected ability of the respirator to reduce the concentration of a contaminant in the inhaled air to a level that is less than the concentration in the ambient air outside the respirator. The higher the APF, the greater the level of protection. APF is an important aspect of workplace safety, ensuring that workers are protected from inhaling harmful substances.

How to Calculate Assigned Protection Factor?

The following steps outline how to calculate the Assigned Protection Factor (APF).

  1. First, measure the concentration of the substance in the air outside the respirator (Concentration Outside) in parts per million (ppm).
  2. Next, measure the concentration of the substance inside the respirator (Concentration Inside) in ppm.
  3. Use the formula APF = Concentration Outside / Concentration Inside.
  4. Finally, calculate the Assigned Protection Factor (APF).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem :

Use the following variables as an example problem to test your knowledge.

Concentration Outside = 100 ppm

Concentration Inside = 5 ppm