[...] seems to show a US postal worker wearing a 3M filtering face piece (FFP) as protection against the threat of anthrax.
2006, AIC News: Newsletter of the American Institute for Conservation of Historic and Artistic Works:
Particulate respirators: filtering face piece respirators (FFPs).
2008, Robert Graysmith, Amerithrax:
Employees supplied with either FFP [filtering face piece] have been advised on proper fit and use to ensure maximum efficiency. [...] fit the FFP to your face.
(mention but has use in table above) 2020, FAO and WHO, Guidelines for personal protection when handling and applying pesticides:
FFP: Filtering Facepiece Particle (see also Annex 5)
(Editor note: Arguably, the above makes no sense, unlike "filtering face piece".)