Research On Quantitative Risk Assessment,Monitoring And Simulation-Based Forewarning Technology Of High-Level Biosafety Facilities

High-level biosafety facilities are not only the basic supporting platform of the national biological defense system,but also an important guarantee for scientific research and services in the field of human health and animal disease prevention and control.Studies on risk assessment of biosafety facilities in China had just started since the SARS epidemic in 2003.Up to now,most risk assessment works are still in the stage of qualitative research.In terms of improving the risk management ability to deal with the leakage of pathogenic microorganisms in high-level biosafety facilities,quantitative risk assessment,monitoring and forewarning technology are of great significance to ensure laboratory biosafety.Scientific and sophisticated risk assessment can not only guide the actual operators of pathogenic microorganisms to choose appropriate biosafety protection strategies,but also assist the managers of biosafety facilities to formulate reasonable risk reduction and hazard control schemes,to reduce the occurrence of dangerous events,lower the risk of pathogen exposure,and mitigate the severity of consequences.In addition,comprehensive and real-time monitoring and forewarning are equally important for safe operation of biosafety facilities.Based on etiological characteristics and field monitoring data,the comprehensive use of information simulation technology can study and judge the infection risk of pathogenic microorganisms and the diffusion range of the external environment,and improve the information and intelligent level of monitoring and forewarning.Therefore,with risk assessment as lead and monitoring and forewarning as support,the development of a "unified,collaborative and linkage" risk assessment,monitoring and forewarning technology system can provide key technical support for the management,operation and emergency response of high-level biosafety facilities in China.The purpose of this study is to carry out risk factors identification for the leakage path of high-level biosafety facilities,build a quantitative risk assessment model covering five ways including " Personnel flow","Air flow","Materials flow","Water flow" and "Solid waste flow",complete the quantitative risk analysis through fault tree Bayesian network,and formulate risk control measures to prevent the leakage of high-level biosafety facilities in combination with the analysis results.At the same time,through computational fluid dynamics technology and dose response model,we carried out simulation deduction and quantitative assessment of the infection risk of environmental pathogenic microorganisms in high-level biosafety facilities through aerosol and object surface,so as to realize the visual monitoring and forewarning of the whole process and space covering the generation,diffusion,deposition,resuspension,exposure and infection of pathogenic microorganism aerosols;By establishing the space-time diffusion model of external environmental leakage of high-level biosafety facilities,the simulation deduction and quantitative evaluation of pathogenic microorganism aerosol diffusion law and infection risk in complex urban environment are carried out to realize the visual tracking of the impact range of external environmental leakage and biosafety hazard forewarning.This study obtained the following four conclusions:1.Risk identification and quantitative risk assessment model of environmental leakage outside high-level biosafety laboratoryBased on the operation,maintenance and management experience of high-level biosafety laboratory,we systematically carried out the full element risk identification of five potential leakage paths of "Personnel flow","Air flow","Materials flow","Water flow" and "Solid waste flow",sorted out the logical relationship between risk factors and drawed the accident tree of five leakage paths based on the fault tree theory.At the same time,around the above accident tree,the Bayesian network model was established based on the Bayesian network transformation law,node fusion and evolution path "pruning".The expert scoring method and fuzzy set theory were used to calculate the a priori probability and conditional probability of the Bayesian network model,and the Bayesian risk assessment model of five leakage paths was successfully constructed,which layed a foundation for the subsequent quantitative calculation of the environmental leakage risk outside the high-level biosafety laboratory.2.Risk analysis and risk control of environmental leakage outside high-level biosafety laboratoryBy using the Bayesian risk assessment model established in the first part for the five potential leakage paths of "Personnel flow","Air flow","Materials flow","Water flow" and "Solid waste flow" in the high-level biosafety laboratory,the quantitative identification of the key influencing factors of laboratory leakage accidents was carried out based on the methods of probability analysis and sensitivity analysis,and the scenario analysis method was used to quantitatively assess the leakage risk under different scenarios,and finally complete the leakage risk analysis of five ways.Combined with the results of risk analysis,risk control measures are formulated to prevent external environmental leakage,and to ensure the safe and effective operation of high-level biosafety laboratory.3.Diffusion model and risk prediction of environmental leakage outside high-level biosafety facilitiesIn order to predict the influence range of biological aerosol leakage and diffusion of high-level biosafety facilities,this study used the earth remote sensing image data to establish a high-precision calculation model of urban environment within 15 km of a highlevel biosafety facility,and integrated the wind speed,wind direction and virus leakage intensity into the simulation and deduction process of the model as input variables.Based on the model,the virus diffusion range and population infection risk of sars-cov-2 aerosol with different concentrations were calculated.The results of this study could support the decision-making of biological hazard protection and emergency management of surrounding facilities.4.Risk monitoring and forewarning of SARS-Co V-2 exposure in negative pressure wardsAccording to the current needs of COVID-19 prevention and control,the negative pressure ward for COVID-19 patients was selected as the research object.According to the architectural drawings and HVAC implementation plan,a visual monitoring model for indoor SARS-Co V-2 aerosol and object surface deposition was established through computational fluid dynamics technology to reveal the diffusion and deposition regularity of SARS-Co V-2 in the negative pressure ward.The simulation results obtained in this study were in good agreement with the actual monitoring data,which further confirmed the reliability of the model.Then,the infection risks of aerosol and object surface routes were calculated by using the dose response model and the spatial distribution regularity of virus particles.Finally,the visualizing infection risk assessment model is applied to the HVAC scheme design of negative pressure ward and the infection risk prediction of mutant strains.This study showed that when the viral load of Sars-Cov-2 mutant strain increased to 50 times,the infection risk of inhalation began to increase exponentially.When the viral load reached 1000 times,even wearing N95 mask,the risk of infection could still reach 90%.The results of this study made up for the blind spot of existing monitoring technology,and could guide the follow-up indoor environment sampling location and key disinfection and sterilization sites,and provide theoretical reference and technical support for nosocomial infection control.