Sensitivity and specificity of the user-seal-check in determining the fit of N95 respirators

N95 respirators are recommended by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) to prevent the inhalation of droplets which may transmit respiratory pathogens. The reliability of N95 respirators in preventing transmission depends on their fit to the wearer. Quantitative fit testing (QNFT) is the gold standard used to determine this fit objectively. The manufacturers of the respirators also recommend performing a self-reported user-seal-check to detect for leakage. This study aims to investigate the capability of the user-seal-check in determining the fit of N95 respirators by investigating the sensitivity and specificity of the user-seal-check compared with QNFT. A prospective and cross-sectional research design was used. A total of 204 local Chinese undergraduate nursing students were recruited to test two commonly used respirator models (3M 1860S and 3M 1862). The results of the user-seal-check were compared with the results of the gold standard QNFT using the Condensation Nucleus Counter Fit Tester System. The sensitivity and specificity of the user-seal-check results obtained with the respirators were calculated. The results indicated low sensitivity, accuracy and predictive value of the user-seal-check in determining the fit of the N95 respirators. The user-seal-check was not found to be reliable as a substitute for QNFT. The results also suggested that the user-seal-check may be unreliable for detecting gross leakage. We recommend that QNFT is used to determine the fit of N95 respirators. (C) 2010 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.