Using Assigned Protection Factors
The National Institute of Occupational Safety (NIOSH) assures a certain standard of protection for men and women who work in environments where hazardous chemicals can enter the body through breathing. An Assigned Protection Factor, or APF, refers to the level of respiratory protection workers are will receive when they use a specific class of respirator.
The APF also helps to determine what is called the Maximum Use Concentration (MUC), which is the highest amount of a hazardous substance that the worker can be protected from while wearing that combination of respirator and filter.
This picture demonstrates a variety of respiratory protection gear and the respective APF. Please note: These should only be applied to a class of respirators when the respirators are properly selected and used in compliance with the OSHA Respiratory Protection Standard 1910.134
NIOSH and the Occupational Safety and Health Administration have online resources to help employers and workers understand respirator types, filter types, APFs and MUCs. Some of these resources are:
These resources contain technical information that is vital to protect the health and safety of workers exposed to chemicals in their workplace air.