Such a nice conversation talking about FDA approvals in those terms and many other things.
https://www.fda.gov/media/136842/download
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpcd/classification.cfm?start_search=1&submission_type_id=&devicename=mask&productcode=&deviceclass=&thirdparty=&panel=®ulationnumber=&implant_flag=&life_sustain_support_flag=&summary_malfunction_reporting=&pagenum=10&sortcolumn=productcodedesc
https://www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-emergency-use-authorizations-medical-devices/personal-protective-equipment-euas#barrier