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Pan Y, Zhang H, Huang W, Liu W, You R, Chen C. Enhancing removal of air contaminants in existing aircraft cabins by optimizing supply air direction based on Re-field synergy and Bayesian optimization. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 928:172363. [PMID: 38614342 DOI: 10.1016/j.scitotenv.2024.172363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/15/2024]
Abstract
There are a large number of airplanes currently being operated, in which the ventilation system needs to be improved to more effectively remove air contaminants. A potential approach is to adjust the supply air directions with the use of simple airflow deflectors. This study proposed a method for optimizing the supply air direction of ventilation in aircraft cabins based on the Re-field synergy index and Bayesian optimization. A validated numerical model was used to calculate the air distribution and air contaminant transport in a single-row single-aisle aircraft cabin to obtain the Re-field synergy values. The Bayesian optimization approach was used to identify the supply air direction which maximizes the Re-field synergy, namely, maximizes the mass transfer effectiveness. Finally, the air contaminant transport in a 7-row single-aisle aircraft cabin with the optimized supply air direction was evaluated to demonstrate the enhancement of ventilation performance. The results show that the proposed method based on the Re-field synergy index and Bayesian optimization can efficiently optimize the supply air direction in order to enhance the air contaminant removal in aircraft cabins. In the 7-row single-aisle aircraft cabin, the optimized supply air direction can reduce the average air contaminant concentration in the breathing zone of the passengers by up to 23 %.
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Affiliation(s)
- Yue Pan
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong
| | - Haiqiang Zhang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong
| | - Wenjie Huang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong
| | - Wei Liu
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China; Department of Civil and Architectural Engineering, KTH Royal Institute of Technology, Stockholm 100 44, Sweden
| | - Ruoyu You
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Kowloon 999077, Hong Kong
| | - Chun Chen
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong; Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong.
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2
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Wang F, Zhang TT, You R, Chen Q. Evaluation of infection probability of Covid-19 in different types of airliner cabins. BUILDING AND ENVIRONMENT 2023; 234:110159. [PMID: 36895516 PMCID: PMC9977471 DOI: 10.1016/j.buildenv.2023.110159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/24/2023] [Accepted: 02/27/2023] [Indexed: 06/09/2023]
Abstract
According to the World Health Organization (https://covid19.who.int/), more than 651 million people have been infected by COVID-19, and more than 6.6 million of them have died. COVID-19 has spread to almost every country in the world because of air travel. Cases of COVID-19 transmission from an index patient to fellow passengers in commercial airplanes have been widely reported. This investigation used computational fluid dynamics (CFD) to simulate airflow and COVID-19 virus (SARS-CoV-2) transport in a variety of airliner cabins. The cabins studied were economy-class with 2-2, 3-3, 2-3-2, and 3-3-3 seat configurations, respectively. The CFD results were validated by using experimental data from a seven-row cabin mockup with a 3-3 seat configuration. This study used the Wells-Riley model to estimate the probability of infection with SARS-CoV-2. The results show that CFD can predict airflow and virus transmission with acceptable accuracy. With an assumed flight time of 4 h, the infection probability was almost the same among the different cabins, except that the 3-3-3 configuration had a lower risk because of its airflow pattern. Flying time was the most important parameter for causing the infection, while cabin type also played a role. Without mask wearing by the passengers and the index patient, the infection probability could be 8% for a 10-h, long-haul flight, such as a twin-aisle air cabin with 3-3-3 seat configuration.
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Affiliation(s)
- Feng Wang
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Tengfei Tim Zhang
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
- School of Civil Engineering, Dalian University of Technology, Dalian, China
| | - Ruoyu You
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
| | - Qingyan Chen
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China
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3
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Sanguinetti A, DePew A, Hirschfelt K. Vehicle Design Strategies to Reduce the Risk of COVID-19 Transmission in Shared and Pooled Travel: Inventory, Typology, and Considerations for Research and Implementation. TRANSPORTATION RESEARCH RECORD 2023; 2677:641-655. [PMID: 38603437 PMCID: PMC9852963 DOI: 10.1177/03611981221141631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
The global COVID-19 pandemic has given rise to a plethora of ideas for modifying and redesigning public transportation and shared mobility vehicles to protect workers and riders from contracting the disease while traveling. This research seeks to inventory these strategies, and to organize and distill them in a way that enables researchers, policymakers, and public transport and mobility service operators to more systematically and efficiently evaluate them. Through literature search and analysis, the COVID-19 risk-mitigating vehicle design (CRVD) typology was developed, articulating 12 categories of strategies (e.g., Seating Configuration, Barriers) and 12 mechanisms (e.g., physical distancing, physical separation) by which the strategies may reduce COVID-19 spread. A secondary contribution of this research is to gather opinions of experts in fields related to COVID-19 and its transmission, about the identified CRVD strategies and mitigation mechanisms. The typology and expert opinions serve as a launching point for further innovation and research to evaluate the effectiveness of CRVD strategies and their relationship to user preferences and travel behavior, within and beyond the current context. Public transport and shared mobility service operators can use the CRVD typology as a reference, in conjunction with industry guidance and emerging research on strategy effectiveness, to aid decision-making in their continued response to the pandemic as well as for future planning.
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Affiliation(s)
- Angela Sanguinetti
- Institute of Transportation Studies,
University of California, Davis, CA
| | - Ashley DePew
- Institute of Transportation Studies,
University of California, Davis, CA
| | - Kate Hirschfelt
- Institute of Transportation Studies,
University of California, Davis, CA
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4
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Liu Z, Wu J, Yang G, Zhang X, Dai Z. A numerical study of COVID-19-laden droplets dispersion in aircraft cabin ventilation system. Heliyon 2023; 9:e13920. [PMID: 36851973 PMCID: PMC9946782 DOI: 10.1016/j.heliyon.2023.e13920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/25/2023] Open
Abstract
Ventilation systems for aircraft cabins are mainly used to maintain a comfortable environment in the cabin and ensure the health of passengers. This study evaluates the decontamination performance of two cabin ventilation systems, the displacement ventilation (DV) system and the mixing ventilation (MV) system, in preventing contamination by virus (COVID-19)-laden droplets. The Euler-Lagrange method was used to computationally model droplet dispersion of different diameters and their behavior in the two systems was contrastively analyzed. Statistics on droplet suspension ratios and duration as well as the infection probability of each passenger were also computed. It was found that11.07% fewer droplet remained suspended in the DV system were than those in the MV system 10s from droplet release. In addition, the number of droplets extracted from the exhausts in the DV system was 13.15% more than the MV system at the 400s mark. In the DV system, higher ambient wind velocities were also found to locally increase infection probability for passengers in certain locations.
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Affiliation(s)
- Zhuxun Liu
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jingyi Wu
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China,Corresponding author.
| | - Guang Yang
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xintai Zhang
- COMAC Shanghai Aircraft Design & Research Institute, Shanghai 201203, China
| | - Zheng Dai
- COMAC Shanghai Aircraft Design & Research Institute, Shanghai 201203, China
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5
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Liu Z, Cao H, Hu C, Wu M, Zhang S, He J, Jiang C. Modeling the infection risk and emergency evacuation from bioaerosol leakage around an urban vaccine factory. NPJ CLIMATE AND ATMOSPHERIC SCIENCE 2023; 6:6. [PMID: 36846520 PMCID: PMC9937520 DOI: 10.1038/s41612-023-00342-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 02/08/2023] [Indexed: 06/18/2023]
Abstract
Mounting interest in modeling outdoor diffusion and transmission of bioaerosols due to the prevalence of COVID-19 in the urban environment has led to better knowledge of the issues concerning exposure risk and evacuation planning. In this study, the dispersion and deposition dynamics of bioaerosols around a vaccine factory were numerically investigated under various thermal conditions and leakage rates. To assess infection risk at the pedestrian level, the improved Wells-Riley equation was used. To predict the evacuation path, Dijkstra's algorithm, a derived greedy algorithm based on the improved Wells-Riley equation, was applied. The results show that, driven by buoyancy force, the deposition of bioaerosols can reach 80 m on the windward sidewall of high-rise buildings. Compared with stable thermal stratification, the infection risk of unstable thermal stratification in the upstream portion of the study area can increase by 5.53% and 9.92% under a low and high leakage rate, respectively. A greater leakage rate leads to higher infection risk but a similar distribution of high-risk regions. The present work provides a promising approach for infection risk assessment and evacuation planning for the emergency response to urban bioaerosol leakage.
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Affiliation(s)
- Zhijian Liu
- School of Energy and Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Hongwei Cao
- School of Energy and Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Chenxing Hu
- School of Mechanical Engineering, Beijing Institute of Technology, Beijing, 100081 China
| | - Minnan Wu
- School of Energy and Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Siqi Zhang
- School of Energy and Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Junzhou He
- School of Energy and Power Engineering, North China Electric Power University, Baoding, 071003 China
| | - Chuan Jiang
- School of Energy and Power Engineering, North China Electric Power University, Baoding, 071003 China
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6
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Lv M, Huang J, Chen H, Zhang TT. An excimer lamp to provide far-ultraviolet C irradiation for dining-table disinfection. Sci Rep 2023; 13:381. [PMID: 36611088 PMCID: PMC9825099 DOI: 10.1038/s41598-023-27380-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 01/02/2023] [Indexed: 01/09/2023] Open
Abstract
Dining tables may present a risk to diners by transmitting bacteria and/or viruses. Currently, there is a lack of an environmental-friendly and convenient means to protect diners when they are sitting together. This investigation constructed far-UVC excimer lamps to disinfect dining-table surfaces. The lamps were mounted at different heights and orientations, and the irradiance on table surfaces was measured. The irradiation doses to obtain different inactivation efficiencies for Escherichia coli (E. coli) were provided. In addition, numerical modeling was conducted for irradiance and the resulting inactivation efficiency. The surface-to-surface (S2S) model was validated with the measured irradiance. The germicidal performance of far-UVC irradiation, the far-UVC doses to which diners were exposed, and the risk of exposure to the generated ozone were evaluated. The results revealed that an irradiation dose of 12.8 mJ/cm2 can disinfect 99.9% of E. coli on surfaces. By varying the lamp irradiance output, the number and positions of the lamps, the far-UVC irradiation can achieve a 3-log reduction for a dining duration of 5 min. Besides, the far-UVC lamp has a low damage risk to diners when achieving an effective inactivation rate. Moreover, there is virtually no ozone exposure risk in a mechanically ventilated dining hall.
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Affiliation(s)
- Mengqiang Lv
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Jin Huang
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Haofu Chen
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Tengfei Tim Zhang
- Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China.
- School of Civil Engineering, Dalian University of Technology, Dalian, China.
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7
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Bennett JS, Mahmoud S, Dietrich W, Jones B, Hosni M. Evaluating vacant middle seats and masks as Coronavirus exposure reduction strategies in aircraft cabins using particle tracer experiments and computational fluid dynamics simulations. ENGINEERING REPORTS : OPEN ACCESS 2022; 5:e12582. [PMID: 36718395 PMCID: PMC9878082 DOI: 10.1002/eng2.12582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/29/2022] [Accepted: 10/01/2022] [Indexed: 06/18/2023]
Abstract
Aircraft cabins have high-performance ventilation systems, yet typically hold many persons in close proximity for long durations. The current study estimated airborne virus exposure and infection reductions when middle seats are vacant compared to full occupancy and when passengers wear surgical masks in aircraft. Tracer particle data reported by U.S. Transportation Command (TRANSCOM) and CFD simulations reported by Boeing were used along with NIOSH data, to build nonlinear regression models with particle exposure and distance from particle source as variables. These models that estimate exposure at given distances from the viral source were applied to evaluate exposure reductions from vacant middle seats. Reductions averaged 54% for the seat row where an infectious passenger is located and 36% for a 24-row cabin containing one infectious passenger, with middle seats vacant. Analysis of the TRANSCOM data showed that universal masking (surgical masks) reduced exposures by 62% and showed masking and physical distancing provide further reductions when practiced together. For a notional scenario involving 10 infectious passengers, compared with no intervention, masking, distancing, and both would prevent 6.2, 3.8, and 7.6 secondary infections, respectively, using the Wells-Riley equation. These results suggest distancing alone, masking alone, and these practiced together reduce SARS CoV-2 exposure risk in increasing order of effectiveness, when an infectious passenger is present.
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Affiliation(s)
- James S. Bennett
- Division of Field Studies and EngineeringNational Institute for Occupational Safety and Health, CDCCincinnatiOhioUSA
| | - Seif Mahmoud
- Division of Field Studies and EngineeringNational Institute for Occupational Safety and Health, CDCCincinnatiOhioUSA
| | - Watts Dietrich
- Division of Field Studies and EngineeringNational Institute for Occupational Safety and Health, CDCCincinnatiOhioUSA
- University of CincinnatiCincinnatiOhioUSA
| | - Byron Jones
- Department of Mechanical and Nuclear EngineeringKansas State UniversityManhattanKansasUSA
| | - Mohammad Hosni
- Department of Mechanical and Nuclear EngineeringKansas State UniversityManhattanKansasUSA
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8
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Ren C, Chen H, Wang J, Feng Z, Cao SJ. Ventilation impacts on infection risk mitigation, improvement of environmental quality and energy efficiency for subway carriages. BUILDING AND ENVIRONMENT 2022; 222:109358. [PMID: 35822126 PMCID: PMC9263602 DOI: 10.1016/j.buildenv.2022.109358] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/27/2022] [Accepted: 06/29/2022] [Indexed: 06/15/2023]
Abstract
Subway carriages are enclosed for extended periods of time, with a high density of passengers. Providing a safe, healthy, and comfortable cabin environment is a great challenge, particularly during the COVID-19 pandemic. An increase in ventilation rate can potentially reduce infection probability, which may result in worsening environmental quality (e.g., thermal comfort) and larger energy consumption. Thus, exploring the trade-off among infection risk, environmental quality (with regard to ventilation, thermal comfort, and air quality), and energy consumption is important to optimize ventilation systems for carriages. The effect of different supply air parameters (e.g., velocity and temperature) and ventilation modes of mixing ventilation (MV) & Supply air from the Floor and Return air from the Ceiling (SFRC) was studied. The questionnaires were analyzed to explore passenger dissatisfaction with the carriage environment using a MV system. Simulations were performed to predict the velocity, temperature, and CO2 concentration fields. In addition, the comprehensive benefit was evaluated by analytic hierarchy process (AHP), based on infection probability from the revisited Wells-Riley equation, Air Diffusion Performance Index (ADPI), Predicted Mean Vote (PMV), Pollutant Removal Effectiveness (PRE) and energy consumption estimated by cooling load (Lcool). Compared with MV, the optimized SFRC provided softer draft sensation and decreased CO2 concentration by 42%. The SFRC achieved better comprehensive benefits, with an infection risk reduced to 0.4%, ADPI of 80%, PMV approaching zero, PRE up to 16, and energy efficiency increased by 30%. This work contributes to the optimal design of subway carriage ventilation systems in the post-epidemic era.
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Affiliation(s)
- Chen Ren
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Haofu Chen
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Junqi Wang
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Zhuangbo Feng
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
| | - Shi-Jie Cao
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096, China
- Global Centre for Clean Air Research, Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom
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9
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Lu Y, Niu D, Zhang S, Chang H, Lin Z. Ventilation indices for evaluation of airborne infection risk control performance of air distribution. BUILDING AND ENVIRONMENT 2022; 222:109440. [PMID: 35937047 PMCID: PMC9339087 DOI: 10.1016/j.buildenv.2022.109440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 07/04/2022] [Accepted: 07/20/2022] [Indexed: 05/12/2023]
Abstract
Air distribution is an effective engineering measure to fight against respiratory infectious diseases like COVID-19. Ventilation indices are widely used to indicate the airborne infection risk of respiratory infectious diseases due to the practical convenience. This study investigates the relationships between the ventilation indices and airborne infection risk to suggest the proper ventilation indices for the evaluation of airborne infection risk control performance of air distribution. Besides the commonly used ventilation indices of the age of air (AoA), air change effectiveness (ACE), and contaminant removal effectiveness (CRE), this study introduces two ventilation indices, i.e., the air utilization effectiveness (AUE) and contaminant dispersion index (CDI). CFD simulations of a hospital ward and a classroom served by different air distributions, including mixing ventilation, displacement ventilation, stratum ventilation and downward ventilation, are validated to calculate the ventilation indices and airborne infection risk. A three-step correlation analysis based on Spearman's rank correlation coefficient, Pearson correlation coefficient, and goodness of fit and a min-max normalization-based error analysis are developed to qualitatively and quantitatively test the validity of ventilation indices respectively. The results recommend the integrated index of AUE and CDI to indicate the overall airborne infection risk, and CDI to indicate the local airborne infection risk respectively regardless of the effects of air distribution, supply airflow rate, infectivity intensity, room configuration and occupant distribution. This study contributes to airborne transmission control of infectious respiratory diseases with air distribution.
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Key Words
- ACE, Air change effectiveness
- AUE, Air utilization effectiveness
- Age of air
- Air change effectiveness
- Air utilization effectiveness
- Airborne infection risk
- AoA, Age of air
- CDI, Contaminant dispersion index
- CRE, Contaminant removal effectiveness
- Contaminant dispersion index
- Contaminant removal effectiveness
- DV, Displacement ventilation
- DWV, Downward ventilation
- MAE, Mean absolute error
- MV, Mixing ventilation
- SV, Stratum ventilation
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Affiliation(s)
- Yalin Lu
- Department of Architecture and Civil Engineering, City University of Hong Kong, China
| | - Dun Niu
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Sheng Zhang
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Han Chang
- School of Human Settlements and Civil Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Zhang Lin
- Division of Building Science and Technology, City University of Hong Kong, China
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10
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Huang J, Hao T, Liu X, Jones P, Ou C, Liang W, Liu F. Airborne transmission of the Delta variant of SARS-CoV-2 in an auditorium. BUILDING AND ENVIRONMENT 2022; 219:109212. [PMID: 35645452 PMCID: PMC9128309 DOI: 10.1016/j.buildenv.2022.109212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/23/2022] [Accepted: 05/16/2022] [Indexed: 05/30/2023]
Abstract
The Delta variant of SARS-CoV-2 has inflicted heavy burdens on healthcare systems globally, although direct evidence on the quantity of exhaled viral shedding from Delta cases is lacking. The literature remains inconclusive on whether existing public health guidance, based on earlier evidence of COVID-19, should respond differently to more infectious viral strains. This paper describes a study on an outbreak of the Delta variant of COVID-19 in an auditorium, where one person contracted the virus from three asymptomatic index cases sitting in a different row. Field inspections were conducted on the configuration of seating, building and ventilation systems. Numerical simulation was conducted to retrospectively assess the exhaled viral emission, decay, airborne dispersion, with a modified Wells-Riley equation used to calculate the inhalation exposure and disease infection risks at the seat level. Results support the airborne disease transmission. The viral emission rate for Delta cases was estimated at 31 quanta per hour, 30 times higher than those of the original variant. The high quantity of viral plume exhaled by delta cases can create a high risk zone nearby, which, for a mixing ventilation system, cannot be easily mitigated by raising mixing rates or introducing fresh air supply. Such risks can be reduced by wearing an N95 respirator, less so for social distancing. A displacement ventilation system, through which the air is supplied at the floor and returned from the ceiling, can reduce risks compared with a mixing system. The study has implications for ventilation guidelines and hygiene practices in light of more infectious viral strains of COVID-19.
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Affiliation(s)
- Jianxiang Huang
- Department of Urban Planning and Design, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
- The University of Hong Kong Shenzhen Institute of Research and Innovation, 5/F, Key Laboratory Platform Building, Shenzhen Virtual University Park, No.6, Yuexing 2nd Rd, Nanshan, Shenzhen, 518057, China
- Sustainable High Density Cities Lab, HKUrban Lab, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
| | - Tongping Hao
- Department of Urban Planning and Design, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
- The University of Hong Kong Shenzhen Institute of Research and Innovation, 5/F, Key Laboratory Platform Building, Shenzhen Virtual University Park, No.6, Yuexing 2nd Rd, Nanshan, Shenzhen, 518057, China
- Sustainable High Density Cities Lab, HKUrban Lab, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
| | - Xiao Liu
- School of Architecture, South China University of Technology, Guangzhou, 510641, China
- Sustainable High Density Cities Lab, HKUrban Lab, The University of Hong Kong, Pokfulam Rd, Hong Kong SAR, China
| | - Phil Jones
- Welsh School of Architecture, Cardiff University, King Edward VII Avenue, Cardiff, United Kingdom
| | - Cuiyun Ou
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
| | - Weihui Liang
- School of Architecture and Urban Planning, Nanjing University, Nanjing, 210093, China
| | - Fuqiang Liu
- Office of Emergency Response to Public Health Emergencies, Hunan Provincial Center for Disease Control and Prevention, No. 450, Section 1, Furong Middle Road, Kaifu District, Changsha City, Hunan Province, China
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11
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Risk Assessment and Prevention Strategy of Virus Infection in the Context of University Resumption. BUILDINGS 2022. [DOI: 10.3390/buildings12060806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The risk assessment system of virus infection probability and the prevention measures for virus transmission are keys to controlling epidemics. In the context of university resumption, this study identifies the risk elements in terms of the mechanism of virus transmission. The effect of two recognized effective measures, i.e., occupancy constraints and ventilation intervention, on the infection risk are quantified and compared using the improved Wells–Riley model. Considering the priority of these two measures, the controlling quantity are determined, and the optimal schemes are proposed based on the targeted infection risk. The results show that the effect of reducing infection risk by constraining occupancy within 25% of all public campus buildings is better than that achieved by increasing the ventilation rate alone. If the ventilation system of the building type is operated by occupiers, it is a priority to prevent the risk of virus infection by restricting occupancy and ensuring the distance between occupants, while if the ventilation system of the building type is centrally controlled, it is a priority to increase the ventilation rate and then limit the occupancy rate during peak periods to 75%.
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12
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Droplets Transmission Mechanism in a Commercial Wide-Body Aircraft Cabin. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12104889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
COVID-19 is a respiratory infectious disease that spreads readily between people, and an urgent issue of passengers’ exposure risk assessment in commercial aircraft has been raised because an aircraft cabin as a confined space may carry and transmit the disease worldwide. In this study, the droplets transmission process under different ventilation systems in a twin-aisle wide-body aircraft was studied using CFD simulations and the infection risk of passengers was assessed by the improved Wells–Riley model. Numerical results found that the transmission mechanism of droplets in the aircraft cabin was different depending on the type of ventilation systems and the location of the infectious source. Annular airflow could effectively enhance the ability of droplets transmission, while direct airflow, represented by displacement ventilation, could significantly inhibit droplets transmission. Accordingly, a new type of ventilation system was proposed based on the concept that the overall space is organized by annular airflow and the local area is direct airflow. Compared with sidewall mixing ventilation system, the infection risk of the new ventilation system presented in this study is reduced by 27%.
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13
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Wang F, You R, Zhang T, Chen Q. Recent progress on studies of airborne infectious disease transmission, air quality, and thermal comfort in the airliner cabin air environment. INDOOR AIR 2022; 32:e13032. [PMID: 35481932 PMCID: PMC9111434 DOI: 10.1111/ina.13032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Revised: 03/03/2022] [Accepted: 03/17/2022] [Indexed: 05/08/2023]
Abstract
Airborne transmission of infectious diseases through air travel has become a major concern, especially during the COVID-19 pandemic. The flying public and crew members have long demanded better air quality and thermal comfort in commercial airliner cabins. This paper reviewed studies related to the airliner cabin air environment that have been published in scientific journals since 2000, to understand the state-of-the-art in cabin air environment design and the efforts made to improve this environment. In this critical review, this paper discusses the challenges and opportunities in studying the cabin air environment. The literature review concluded that current environmental control systems for airliner cabins have done little to stop the airborne transmission of infectious diseases. There were no reports of significant air quality problems in cabins, although passengers and crew members have complained of some health-related issues. The air temperature in cabins needs to be better controlled, and therefore, better thermal comfort models for airliners should be developed. Low humidity is a major complaint from passengers and crew members. Gaspers are used by passengers to adjust thermal comfort, but they do not improve air quality. Various personalized and displacement ventilation systems have been developed to improve air quality and thermal comfort. Air cleaning technologies need to be further developed. Good tools are available for designing a better cabin air environment.
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Affiliation(s)
- Feng Wang
- Tianjin Key Laboratory of Indoor Air Environmental Quality ControlSchool of Environmental Science and EngineeringTianjin UniversityTianjinChina
- Department of Building Environment and Energy EngineeringThe Hong Kong Polytechnic UniversityKowloon, Hong Kong SARChina
| | - Ruoyu You
- Department of Building Environment and Energy EngineeringThe Hong Kong Polytechnic UniversityKowloon, Hong Kong SARChina
| | - Tengfei Zhang
- Tianjin Key Laboratory of Indoor Air Environmental Quality ControlSchool of Environmental Science and EngineeringTianjin UniversityTianjinChina
| | - Qingyan Chen
- Department of Building Environment and Energy EngineeringThe Hong Kong Polytechnic UniversityKowloon, Hong Kong SARChina
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Fan M, Fu Z, Wang J, Wang Z, Suo H, Kong X, Li H. A review of different ventilation modes on thermal comfort, air quality and virus spread control. BUILDING AND ENVIRONMENT 2022; 212:108831. [PMID: 35125624 PMCID: PMC8799382 DOI: 10.1016/j.buildenv.2022.108831] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/11/2022] [Accepted: 01/21/2022] [Indexed: 05/12/2023]
Abstract
In the era of Corona Virus Disease 2019 (COVID-19), inappropriate indoor ventilation may turn out to be the culprit of microbial contamination in enclosed spaces and deteriorate the environment. To collaboratively improve the thermal comfort, air quality and virus spread control effect, it was essential to have an overall understanding of different ventilation modes. Hence, this study reviewed the latest scientific literature on indoor ventilation modes and manuals of various countries, identified characteristics of different ventilation modes and evaluated effects in different application occasions, wherefore to further propose their main limitations and solutions in the epidemic era. For thermal comfort, various non-uniform ventilation modes could decrease the floor-to-ceiling temperature difference, draft rate or PPD by 60%, 80% or 33% respectively, or increase the PMV by 45%. Unsteady ventilation modes (including intermittent ventilation and pulsating ventilation) could lower PPD values by 12%-37.8%. While for air quality and virus spread control, non-uniform ventilation modes could lower the mean age of air or contaminants concentration by 28.3%-47% or 15%-47% respectively, increase the air change efficiency, contaminant removal effectiveness or protection efficiency by 6.6%-10.4%, 22.6% or 14%-50% respectively. Unsteady ventilation mode (pulsating ventilation) could reduce the peak pollutant concentration and exposure time to undesirable concentrations by 31% and 48% respectively. Non-uniform modes and unsteady modes presented better performance in thermal comfort, air quality and virus spread control, whereas relevant performance evaluation indexes were still imperfect and the application scenarios were also limited.
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Affiliation(s)
- Man Fan
- School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Zheng Fu
- School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Jia Wang
- School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Zhaoying Wang
- School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Hanxiao Suo
- School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Xiangfei Kong
- School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
| | - Han Li
- School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin, 300401, China
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