What does 99PFE mean?

Definition of "99PFE" in the Dorma 99 mask description

A 99PFE respirator is a filtering facepiece respirator (FFR) designed to protect the wearer from harmful airborne contaminants. There are several types of filtering masks used as part of personal protective equipment (PPE) in health care, industrial or commercial environments.
Filter masks are designed to protect the user against inhalation of small particles or aerosols, including infectious particles. Respirators are categorized according to their level of filtration and are labeled “95PFE”, “99PFE” or “100PFE”. These are equivalent to N95, N99, and N100 masks, respectively.

“99PFE” indicates greater than or equal to 99% particulate filter efficiency. This rating may be paired with “-L1,” -L2,” or “-L3” to indicate that it is a surgical respirator. “99PFE-L3” means that the respirator offers at least 99% filtration efficiency, and level 3 surgical masks protection (fluid resistance, bacterial efficiency, etc.).