What to Know About KN95 Face Masks – WSJ

August 23, 2020

https://www.wsj.com/articles/what-to-know-about-kn95-face-masks-11596460569

has some useful lists of bad KN95 masks, viz:

https://www.cdc.gov/niosh/npptl/respirators/testing/NonNIOSHresults.html

https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-emergency-use-authorizations-medical-devices/personal-protective-equipment-euas