ABSTRACT
Two and half years into the COVID-19 pandemic, there is quite a lot of confusion over public health guidance necessary in order to reduce disease infection risks, from room air ventilation, the use of air cleaners, and type of mask and whether or not to wear a mask. This paper describes the development of a novel web-based calculator for use by the public to assess COVID-19 infection risks between a source and receiver in a typical room. The aim is to inform the disease infection risk in response to varying exposure times, mask-wearing, and viral variant in circulation. The calculator is based on the state-of-the-art research evidence, i.e., a room air ventilation model, mask infiltration efficiencies, room cleaner efficiencies, the quanta emission rates of various viral variants of COVID-19, and the modified Wells Riley equations. The results show that exposure times are critical in determining transmission risk. Masks are important and can reduce infection risk especially over shorter exposure times and for lower source emission quantum. N95 respirators are by far the most effective, especially for Omicron, and the results indicate that N95 respirators are necessary for the more infectious variants. Increasing fresh air ventilation rates from 2ac/h to 6ac/h can have a considerable impact in reducing transmission risk in a well-mixed space. Going from 6 ac/h to 12ac/h is less effective especially at lower exposure times. Venues can be classified in terms of risk, and appropriate high ventilation rates might be recommended for high-risk, speaking loudly and singing, such as classrooms and theatres. However, for low risk, quiet and speaking softly venues, such as offices and libraries, higher ventilation rates may not be required;instead, mechanical ventilation systems in combination with air cleaners can effectively remove small fraction size aerosol particles. The web-based calculator provides an easy-to-use and valuable tool for use in estimating infection risk.
ABSTRACT
Objective: To explore the psychological status of medical staff during COVID-19 epidemic, so as to provide reference and scientific basis for carrying out further psychological intervention and ensuring the mental health of medical staff. Methods: By using convenient sampling method and the Stresss-Anxiety ubscale of Depression Anxiety Stress (DASS-21) , the mental health status of 615 medical staff was investigated by the way of questionnaire star from February 4 to 16, 2020. A total of 615 questionnaires were distributed and collected, and 615 were valid, with an effective recovery rate of 100%. Results: The detection rates of psychological stress and anxiety of medical staff were 13.82% (85/615) and 25.37% (156/615) , respectively. 31-40 years old and working in key departments were risk factors for psychological stress of medical staff (OR=1.779, 2.127) ; Women, frequently washing hands with soap/hand sanitizer/disinfectant were protective factors for psychological stress (OR=0.520, 0.528) . Medical staff working in designated hospitals and key departments were more likely to have anxiety (OR=2.042, 2.702) ; The high fit of the mask to the face and bridge of the nose was a protective factor for the psychological anxiety of medical staff (OR=0.500) . Conclusion: Medical staff show higher stress and anxiety during the epidemic of COVID-19. Psychological intervention should be carried out early, focusing on men, age 31 to 40, medical staff working in designated hospitals and key departments.