What do OSHA's assigned protection factors (APFs) indicate?

OSHA's assigned protection factors (APFs) are designed to quantify the level of protection that a respirator can provide to the wearer in a hazardous environment. Specifically, an APF indicates how much the respirator reduces the concentration of airborne contaminants that can be inhaled by the user compared to the outside air. This factor helps determine the appropriate type of respirator for specific work conditions and aids in ensuring that workers are adequately protected from exposure to harmful substances such as asbestos.

By using APFs, employers and safety professionals can assess and select respirators that offer a suitable level of protection based on the task and the level of contaminant exposure. It is essential to recognize that APFs are not related to the duration of use, the weight of the respirator, or its cost, as these factors address different aspects of respirator selection and use.