Layering a surgical mask over an N95 may cause leakage, according to a study published Dec. 20 in Infection Control & Hospital Epidemiology.
The study, led by researchers at Mayo Clinic Phoenix and the University of Tulsa (Okla.), involved 100 participants who successfully completed quantitative fit testing while wearing a 3M 1870+ filtering facepiece respirator. When a procedural mask was placed over the N95, 13 percent of participants failed subsequent fit testing, the findings showed.
"The additional resistance created by an overlying face mask can lead to increased airway pressures that cause leakage at the N95 FFR facial seal," researchers said.