Explanation:
According to OSHA, “Assigned protection factor (APF) refers to the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when the employer implements a continuing, effective respiratory protection program as specified by this section.”APF is a measure of the concentration of a contaminant both outside and inside a respirator. The greater the number, the more effective a respirator is at removing a contaminant.