Water-blocking Asphyxia of N95 Medical Respirator During Hot Environment Work Tasks With Whole-body Enclosed Anti-bioaerosol Suit

Background: During hot environment work tasks with whole -body enclosed anti-bioaerosol suit, the combined effect of heavy sweating and exhaled hot humid air may cause the N95 medical respirator to saturate with water/sweat (i.e., water -blocking). Methods: 32 young male subjects with different body mass indexes (BMI) in whole -body protection (N95 medical respirator + one-piece protective suit + head covering + protective face screen + gloves + shoe covers) were asked to simulate waste collecting from each isolated room in a seven -story building at 2728 degrees C, and the weight, inhalation resistance (Rf), and aerosol penetration of the respirator before worn and after water -blocking were analyzed. Results: All subjects reported water -blocking asphyxia of the N95 respirators within 36-67 min of the task. When water -blocking occurred, the Rf and 10-200 nm total aerosol penetration (Pt) of the respirators reached up to 1270-1810 Pa and 17.3-23.3%, respectively, which were 10 and 8 times of that before wearing. The most penetration particle size of the respirators increased from 49-65 nm before worn to 115-154 nm under water -blocking condition, and the corresponding maximum size -dependent aerosol penetration increased from 2.5-3.5% to 20-27%. With the increase of BMI, the water -blocking occurrence time firstly increased then reduced, while the Rf, Pt, and absorbed water all increased significantly. Conclusions: This study reveals respirator water -blocking and its serious negative impacts on respiratory protection. When performing moderate -to -high -load tasks with whole -body protection in a hot environment, it is recommended that respirator be replaced with a new one at least every hour to avoid water -blocking asphyxia. (c) 2023 The Authors. Published by Elsevier B.V. on behalf of Occupational Safety and Health Research Institute, Korea Occupational Safety and Health Agency. This is an open access article under the CC BYNC -ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).