What is PM2.5 BFE? July 14, 2020 23:48 Updated BFE stands for Bacterial Filtration Efficiency — meaning it can filter PM (particulate matter) of 2.5 microns! Related articles Are you making sure people on the frontline get them first? What is FIONx™? Do you need to replace the filters? My order has not shipped yet. Can I adjust an embroidery order after I’ve placed it?