Inclusion criteria  Adult (18 years old or greater) ED providers (MDs, nurses, Advanced Practice Providers (APPs)) who are practicing extended use and re-use for the majority (more than half) of their shifts Participants are eligible when obtaining a new N95 and are scheduled to work a minimum of 5 shifts within a 60-day period. As hours of enrollment and data collection depend on research associate availability, participants working certain shifts may not be eligible.  Exclusion criteria:  Participant does not intend to use N95 for majority of shift Schedule prohibits re-use and or data collection Repeated failed baseline fit test Refused or unable to consent Pregnant Facial hair (e.g., beards or sideburns) or jewelry which interferes with the face seal region of an N95