The risk of aerosol transmission of respiratory infectious diseases in the isolation ward
Nosocomial infections have caused significant health and socio-economic losses to patients,healthcare workers,and the nation.Aerosols can carry various pathogens and serve as important media for the transmission of nosocomial infections.Airborne transmission is a crucial pathway for nosocomial infections.During routine diagnosis,treatment,and epidemic prevention and control,healthcare workers often need to have close contact with patients and are exposed to aerosols exhaled by patients.Calculating the concentration of pathogens in hospitals and assessing the infection risk is of great significance in reducing the occurrence of nosocomial infections and responding to newly emerging infectious diseases.Currently,most studies on infection risk assessment are based solely on simulations of spatial and temporal distributions of aerosols exhaled by patients,making it difficult to accurately calculate the distribution of viral concentration and infection risk.In this study,the computational fluid dynamics(CFD)method is employed to simulate the dispersion and deposition of aerosols exhaled by infected patients in the isolation ward at Wuhan Huoshenshan Hospital.A quantitative microbial risk analysis(QMRA)model is developed to evaluate the risk of both inhalation and surface contact infections within the mentioned ward,taking into consideration uncertainties regarding viral loads,virus half-life,deposition on respiratory tracts,ventilation,protective measures,and personnel activity.Subsequently,the risk distribution within the isolation ward and the probability of infection among medical staff under various conditions are calculated.The findings of this study reveal significant spatial heterogeneity in the risk distribution within the negative isolation ward.The transport and deposition of viral aerosols are strongly influenced by airflow dynamics and ventilation systems,resulting in the formation of high-risk areas within the ward.Moreover,it is observed that the risk of inhalation infection is closely associated with the intensity of individual activity and the depth of breathing.At high activity levels,the risk of infection can be approximately twice as high as that at moderate activity levels.Furthermore,the calculations demonstrate that the utilization of N95 masks can substantially reduce the risk of inhalation infection by 60％-90％.It is worth noting that certain mutations of SARS-CoV-2 may result in an elevated viral load and subsequently an increased risk of infection.Based on these findings,this study concludes that the utilization of appropriate personal protective equipment such as N95 masks,face masks,and disposable gloves can effectively mitigate the risk of infection among medical and nursing staff.Furthermore,rearranging office areas to avoid high-risk zones,adjusting disinfection intervals within wards to prevent the build-up of high viral concentrations on object surfaces,implementing strict control over the working hours of medical and nursing staff,and enhancing protection measures for patients with mutant strains of the infection are all effective measures in reducing the risk of infection.Special attention should also be given to the influence of individual variations in infection.The outcomes of this study can serve as a theoretical reference and offer technical support for the prevention and reduction of nosocomial infections.
isolation wardnosocomial infectiontransmission of aerosolscomputational fluid dynamics(CFD)simulationinfection risk assessment
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