Assigned Protection Factor (APF)
Assigned Protection Factor (APF) means 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. When required by OSHA for reducing exposure to silica dust using the previous equipment discussed in this module, using respiratory protection with an APF of 10 is required.
Maximum Use Concentration (MUC)
Maximum Use Concentration (MUC) means the maximum atmospheric concentration of a hazardous substance from which an employee can be expected to be protected when wearing a respirator. The MUC is determined by the assigned protection factor of the respirator or class of respirators and the exposure limit of the hazardous substance.
The MUC for respirators is calculated by multiplying the APF for the respirator by the PEL. The MUC is the upper limit at which the class of respirator is expected to provide protection. Whenever the exposures approach the MUC, then the employer should select the next higher class of respirators for the employees.
For more information on APFs and MUCs, refer to OSHA Publication 3352-02, Assigned Protection Factors (pdf).
Knowledge Check Choose the best answer for the question.
4-3. What is the APF value required for respirators when they are used for reducing exposure to silica dust?
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