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°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.
ABSTRACT
Objective To investigate the mechanism of pulmonary inflammation induced by influenza virus , and provide reference for the development of effective drugs for viral pneumonia .Methods An influenza PR8 infection mouse model was established .The levels of inflammatory cytokines and complement molecules were determined using RT -PCR and ELISA.The pathological changes were examined using biopsy .The complement inhibitor cobra venom factor ( CVF) was injected intraperitoneally at a dose of 50 μg/( kg· 24 h) , and then body mass .The survival rate and inflammatory factors were examined .Results Compared with the control group , the expressions of complement regulatory molecule Crry and CD59 were significantly decreased (P<0.01), while those of complement C9 and complement receptor C3aR and C5aR were significantly increased in the lungs of influenza model mice (P<0.01).Pro-inflammatory cytokines TNF-α, IL-6 and IFN-γwere highly expressed , but anti-inflammatory cytokine IL-2 was lowly expressed in serum .Treatment with CVF caused a sight body mass loss, a survival rate increase and a lung index decrease (P <0.05).Moreover, an IL-2 expression increase and a decrease of IL-6, TNF -αand INF-γexpression were observed in CVF treatment mice ( P< 0.05).Conclusion Inhibition of complement activation can increase the survival rate of mice with influenza pneumonia and decrease pulmonary indexes .thus delaying the pathogenesis of PR 8.