Approximately 30% of health care workers (HCWs) fail the respirator fit test . Evidence suggests that addressing face leaks in the 3M respirator enhances its fit and improves its efficacy . Between March 31 and April 9 , 2020, HCWs who failed fit tests for 3M 1860 and 1860S respirators were invited to retest with an adhesive modification of the 3M respirator . Sixty-eight percent of HCWs who failed the fit test with their first-choice respirator passed with a modified adhesive respirator . To increase the efficacy and safety of 3M respirators, ineffective face seals need substantial improvement in design.