Degesys NF, Wang RC, Kwan E, et al. - In many emergency departments, insufficient supplies of N95 respirators (N95s) have forced to implement various N95 reuse and extended use policies but without empirical evidence of their effectiveness. Researchers here investigated the prevalence of N95 fit test failure while reusing 2 common types of N95 masks. In this cross-sectional study of N95 fit at the University of California, San Francisco emergency department, enrollment of a convenience sample of 68 health care workers (physicians, nurses, nurse practitioners, physician assistants, and patient care technicians) was performed on their clinical shifts when the researchers were present. Among participants, 51 (75.0%) used dome-shaped N95s and 17 (25.0%) used duckbill N95s. Observations revealed a high failure rate with duckbill N95s. Increased use was observed to be correlated with failure of dome-shaped masks.