Safety and Health at Work

Occupational Safety and Health Research Institute, Korea Occupational Safety and Health Agency (산업안전보건연구원)
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Water-blocking Asphyxia of N95 Medical Respirator During Hot Environment Work Tasks With Whole-body Enclosed Anti-bioaerosol Suit

  • Jintuo Zhu (Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of Education) ;
  • Qijun Jiang (Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of Education) ;
  • Yuxuan Ye (Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of Education) ;
  • Xinjian He (Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of Education) ;
  • Jiang Shao (School of Architecture & Design, China University of Mining and Technology) ;
  • Xinyu Li (Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of Education) ;
  • Xijie Zhao (School of Architecture & Design, China University of Mining and Technology) ;
  • Huan Xu (School of Materials Science and Physics, China University of Mining and Technology) ;
  • Qi Hu (Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of Education)
  • Received : 2023.07.27
  • Accepted : 2023.10.19
  • Published : 2023.12.30
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Abstract

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 27-28℃, 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.

Keywords

Acknowledgement

We thank the human subjects who took part in the study, students who supported the work and teachers who assisted the field investigation.

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