Abstract： Objective:To evaluate the effects of wearing N95 mask on the quality of chest compression and fatigue.Methods:A total of 80 participants from Zhongnan Hospital with basic life support (BLS) certification conferred by American Heart Association (AHA) within two years were enrolled. After reviewing the key points of cardiopulmonary resuscitation (CPR) and grasping the operation on the manikin, they were randomized (random number) into two groups: wearing surgical masks (SM group, n=40) and wearing N95 masks (N95 group, n=40) during CPR. Each participant performed a 2-minute chest compression-only CPR on the manikin. Participants' height, body weight, Borg scores and physiological parameters before and after CPR were recorded. The quality of chest compression (including compression depth, compression rate, adequate depth proportions, adequate rate proportions, hand position and complete chest recoil) were recorded by Laerdal QCPR ? software. Student's t test and Mann-Whitney test were used to compare the differences of chest compression quality indexes between the two groups. Results:Compared with the SM group, participants in the N95 group had significantly increased median of Borg scores after CPR (16 vs 14, P=0.027), and decreased quality of chest compression, including the decline in compression depth (mean 47 mm vs 52 mm, P=0.020), compression rate (107 times/min vs 118 times/min, P=0.004), complete chest recoil rate (89.8% vs 98.1%, P=0.046), adequate depth proportions (67.4% vs 89.6%, P<0.01) and adequate rate proportions (60.6% vs 74.8%, P<0.01). Conclusions:Wearing N95 masks during CPR decreases the quality of chest compression and aggravates rescuers’ fatigue. Therefore, it is necessary to exchange rescuers more frequently to ensure the quality of chest compression when wearing N95 masks.