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Feng Y, Zhang Y, Ding X, Fan Y, Ge J. Multi-scale risk assessment and mitigations comparison for COVID-19 in urban public transport: A combined field measurement and modeling approach. BUILDING AND ENVIRONMENT 2023; 242:110489. [PMID: 37333517 PMCID: PMC10236904 DOI: 10.1016/j.buildenv.2023.110489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/31/2023] [Accepted: 06/02/2023] [Indexed: 06/20/2023]
Abstract
The outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused an unparalleled disruption to daily life. Given that COVID-19 primarily spreads in densely populated indoor areas, urban public transport (UPT) systems pose significant risks. This study presents an analysis of the air change rate in buses, subways, and high speed trains based on measured CO2 concentrations and passenger behaviors. The resulting values were used as inputs for an infection risk assessment model, which was used to quantitatively evaluate the effects of various factors, including ventilation rates, respiratory activities, and viral variants, on the infection risk. The findings demonstrate that ventilation has a negligible impact on reducing average risks (less than 10.0%) for short-range scales, but can result in a reduction of average risks by 32.1%-57.4% for room scales. When all passengers wear masks, the average risk reduction ranges from 4.5-folds to 7.5-folds. Based on our analysis, the average total reproduction numbers (R) of subways are 1.4-folds higher than buses, and 2-folds higher than high speed trains. Additionally, it is important to note that the Omicron variant may result in a much higher R value, estimated to be approximately 4.9-folds higher than the Delta variant. To reduce disease transmission, it is important to keep the R value below 1. Thus, two indices have been proposed: time-scale based exposure thresholds and spatial-scale based upper limit warnings. Mask wearing provides the greatest protection against infection in the face of long exposure duration to the omicron epidemic.
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Affiliation(s)
- Yinshuai Feng
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- Center for Balance Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Yan Zhang
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Xiaotian Ding
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Yifan Fan
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- Center for Balance Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
| | - Jian Ge
- College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China
- International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China
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Moschovis PP, Lombay J, Rooney J, Schenkel SR, Singh D, Rezaei SJ, Salo N, Gong A, Yonker LM, Shah J, Hayden D, Hibberd PL, Demokritou P, Kinane TB. The effect of activity and face masks on exhaled particles in children. Pediatr Investig 2023; 7:75-85. [PMID: 37324601 PMCID: PMC10262878 DOI: 10.1002/ped4.12376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 01/29/2023] [Indexed: 06/17/2023] Open
Abstract
Importance Despite the high burden of respiratory infections among children, the production of exhaled particles during common activities and the efficacy of face masks in children have not been sufficiently studied. Objective To determine the effect of type of activity and mask usage on exhaled particle production in children. Methods Healthy children were asked to perform activities that ranged in intensity (breathing quietly, speaking, singing, coughing, and sneezing) while wearing no mask, a cloth mask, or a surgical mask. The concentration and size of exhaled particles were assessed during each activity. Results Twenty-three children were enrolled in the study. Average exhaled particle concentration increased by intensity of activity, with the lowest particle concentration during tidal breathing (1.285 particles/cm3 [95% CI 0.943, 1.627]) and highest particle concentration during sneezing (5.183 particles/cm3 [95% CI 1.911, 8.455]). High-intensity activities were associated with an increase primarily in the respirable size (≤ 5 µm) particle fraction. Surgical and cloth masks were associated with lower average particle concentration compared to no mask (P = 0.026 for sneezing). Surgical masks outperformed cloth masks across all activities, especially within the respirable size fraction. In a multivariable linear regression model, we observed significant effect modification of activity by age and by mask type. Interpretation Similar to adults, children produce exhaled particles that vary in size and concentration across a range of activities. Production of respirable size fraction particles (≤ 5 µm), the dominant mode of transmission of many respiratory viruses, increases significantly with coughing and sneezing and is most effectively reduced by wearing surgical face masks.
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Affiliation(s)
- Peter P. Moschovis
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Jesiel Lombay
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Jennifer Rooney
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Sara R. Schenkel
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Dilpreet Singh
- Department of Environmental HealthHarvard T. H. Chan School of Public HealthBostonMassachusettsUSA
- Department of Mechanical and Aerospace EngineeringRutgers University School of Public HealthNew BrunswickNew JerseyUSA
| | - Shawheen J. Rezaei
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Nora Salo
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Amanda Gong
- David Geffen School of Medicinethe University of California Los AngelesLos AngelesCaliforniaUSA
| | - Lael M. Yonker
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Jhill Shah
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Douglas Hayden
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
| | - Patricia L. Hibberd
- Department of Global HealthBoston University School of Public HealthBostonMassachusettsUSA
| | - Philip Demokritou
- Department of Environmental HealthHarvard T. H. Chan School of Public HealthBostonMassachusettsUSA
- Department of Mechanical and Aerospace EngineeringRutgers University School of Public HealthNew BrunswickNew JerseyUSA
| | - T. Bernard Kinane
- Department of PediatricsMassachusetts General Hospital and Harvard Medical SchoolBostonMassachusettsUSA
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Maciá-Pérez F, Lorenzo-Fonseca I, Berná-Martínez JV. Dynamic ventilation certificate for smart universities using artificial intelligence techniques. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023; 236:107572. [PMID: 37121212 PMCID: PMC10129909 DOI: 10.1016/j.cmpb.2023.107572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 03/20/2023] [Accepted: 04/25/2023] [Indexed: 05/04/2023]
Abstract
The issue of room ventilation has recently gained momentum due to the COVID-19 pandemic. Ventilation is in fact of particular relevance in educational environments. Smart University platforms, today widespread, are a good starting point to offer control services of different relevant indicators in universities. This study advances a Ventilation Quality Certificate (VQC) for Smart Universities. The certificate informs the university community of the ventilation status of its buildings and premises. It also supports senior management's decision-making, because it allows assessing preventive measures and actions taken. The VQC algorithm models the adequacy of classroom ventilation according to the number of persons present. The input used is the organisation's existing data relating to CO2 concentration and number of room occupants. AI techniques, specifically Artificial Neural Networks (ANN), were employed to determine the relationship between the different data sources included. A prototype of value-added services was developed for the Smart University platform of the University of Alicante, which allowed to implement the resulting models, together with the VQC. The prototype is currently being replicated in other universities. The case study allowed us to validate the VQC, demonstrating both its usefulness and the advantage of using pre-existing university services and resources.
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Clements N, Arvelo I, Arnold P, Heredia NJ, Hodges UW, Deresinski S, Cook PW, Hamilton KA. Informing Building Strategies to Reduce Infectious Aerosol Transmission Risk by Integrating DNA Aerosol Tracers with Quantitative Microbial Risk Assessment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:5771-5781. [PMID: 37000413 DOI: 10.1021/acs.est.2c08131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Using aerosol-based tracers to estimate risk of infectious aerosol transmission aids in the design of buildings with adequate protection against aerosol transmissible pathogens, such as SARS-CoV-2 and influenza. We propose a method for scaling a SARS-CoV-2 bulk aerosol quantitative microbial risk assessment (QMRA) model for impulse emissions, coughing or sneezing, with aerosolized synthetic DNA tracer concentration measurements. With point-of-emission ratios describing relationships between tracer and respiratory aerosol emission characteristics (i.e., volume and RNA or DNA concentrations) and accounting for aerosolized pathogen loss of infectivity over time, we scale the inhaled pathogen dose and risk of infection with time-integrated tracer concentrations measured with a filter sampler. This tracer-scaled QMRA model is evaluated through scenario testing, comparing the impact of ventilation, occupancy, masking, and layering interventions on infection risk. We apply the tracer-scaled QMRA model to measurement data from an ambulatory care room to estimate the risk reduction resulting from HEPA air cleaner operation. Using DNA tracer measurements to scale a bulk aerosol QMRA model is a relatively simple method of estimating risk in buildings and can be applied to understand the impact of risk mitigation efforts.
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Affiliation(s)
- Nicholas Clements
- Paul M. Rady Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309, United States
| | - Ilan Arvelo
- SafeTraces, Inc., Pleasanton, California 94588, United States
| | - Phil Arnold
- SafeTraces, Inc., Pleasanton, California 94588, United States
| | | | - Ulrike W Hodges
- SafeTraces, Inc., Pleasanton, California 94588, United States
| | - Stan Deresinski
- Stanford University School of Medicine, Stanford, California 94305, United States
| | - Peter W Cook
- Independent researcher, Atlanta, Georgia 30333, United States
| | - Kerry A Hamilton
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85281, United States
- The Biodesign Institute Center for Environmental Health Engineering, Arizona State University, Tempe, Arizona 85281, United States
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Zhao Y, Gu C, Song X. Evaluation of indoor environmental quality, personal cumulative exposure dose, and aerosol transmission risk levels inside urban buses in Dalian, China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:55278-55297. [PMID: 36884177 PMCID: PMC9994408 DOI: 10.1007/s11356-023-26037-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 02/16/2023] [Indexed: 06/09/2023]
Abstract
The transmission of pollutants in buses has an important impact on personal exposure to airborne particles and spread of the COVID-19 epidemic in enclosed spaces. We conducted the following real-time field measurements inside buses: CO2, airborne particle concentration, temperature, and relative humidity data during peak and off-peak hours in spring and autumn. Correlation analysis was adopted to evaluate the dominant factors influencing CO2 and particle mass concentrations in the vehicle. The cumulative personal exposure dose to particulate matter and reproduction number were calculated for passengers on a one-way trip. The results showed the in-cabin CO2 concentrations, with 22.11% and 21.27% of the total time exceeding 1000 ppm in spring and autumn respectively. In-cabin PM2.5 mass concentration exceeded 35 μm/m3 by 57.35% and 86.42% in spring and autumn, respectively. CO2 concentration and the cumulative number of passengers were approximately linearly correlated in both seasons, with R value up to 0.896. The cumulative number of passengers had the most impact on PM2.5 mass concentration among tested parameters. The cumulative personal exposure dose to PM2.5 during a one-way trip in autumn was up to 43.13 μg. The average reproductive number throughout the one-way trip was 0.26; it was 0.57 under the assumed extreme environment. The results of this study provide an important basic theoretical guidance for the optimization of ventilation system design and operation strategies aimed at reducing multi-pollutant integrated health exposure and airborne particle infection (such as SARS-CoV-2) risks.
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Affiliation(s)
- Yu Zhao
- Ganjingzi District, School of Civil Engineering, Faculty of Infrastructure Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Chenmin Gu
- Ganjingzi District, School of Civil Engineering, Faculty of Infrastructure Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Xiaocheng Song
- Civil and Architectural Engineering College, Dalian University, 10 Xuefu Street, Economic & Technological Development Zone, Dalian, 116622, China.
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Glenn K, He J, Rochlin R, Teng S, Hecker JG, Novosselov I. Assessment of aerosol persistence in ICUs via low-cost sensor network and zonal models. Sci Rep 2023; 13:3992. [PMID: 36899063 PMCID: PMC10006437 DOI: 10.1038/s41598-023-30778-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 03/01/2023] [Indexed: 03/12/2023] Open
Abstract
The COVID-19 pandemic raised public awareness about airborne particulate matter (PM) due to the spread of infectious diseases via the respiratory route. The persistence of potentially infectious aerosols in public spaces and the spread of nosocomial infections in medical settings deserve careful investigation; however, a systematic approach characterizing the fate of aerosols in clinical environments has not been reported. This paper presents a methodology for mapping aerosol propagation using a low-cost PM sensor network in ICU and adjacent environments and the subsequent development of the data-driven zonal model. Mimicking aerosol generation by a patient, we generated trace NaCl aerosols and monitored their propagation in the environment. In positive (closed door) and neutral-pressure (open door) ICUs, up to 6% or 19%, respectively, of all PM escaped through the door gaps; however, the outside sensors did not register an aerosol spike in negative-pressure ICUs. The K-means clustering analysis of temporospatial aerosol concentration data suggests that ICU can be represented by three distinct zones: (1) near the aerosol source, (2) room periphery, and (3) outside the room. The data suggests two-phase plume behavior: dispersion of the original aerosol spike throughout the room, followed by an evacuation phase where "well-mixed" aerosol concentration decayed uniformly. Decay rates were calculated for positive, neutral, and negative pressure operations, with negative-pressure rooms clearing out nearly twice as fast. These decay trends closely followed the air exchange rates. This research demonstrates the methodology for aerosol monitoring in medical settings. This study is limited by a relatively small data set and is specific to single-occupancy ICU rooms. Future work needs to evaluate medical settings with high risks of infectious disease transmission.
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Affiliation(s)
- K Glenn
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - J He
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - R Rochlin
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - S Teng
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - J G Hecker
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, USA
| | - I Novosselov
- Department of Mechanical Engineering, University of Washington, Seattle, USA.
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Kumar P, Omidvarborna H, Yao R. A parent-school initiative to assess and predict air quality around a heavily trafficked school. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 861:160587. [PMID: 36470381 DOI: 10.1016/j.scitotenv.2022.160587] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 11/19/2022] [Accepted: 11/26/2022] [Indexed: 06/17/2023]
Abstract
Many primary schools in the UK are situated in close proximity to heavily-trafficked roads, yet long-term air pollution monitoring around such schools to establish factors affecting the variability of exposure is limited. We co-designed a study to monitor particulate matter in different size fractions (PM1, PM2.5, PM10), gaseous pollutants (NO2, O3 and CO) and meteorological parameters (ambient temperature, relative humidity) over a period of one year. The period included phases of national COVID-19 lockdown and its subsequent easing and removal. Statistical analysis was used to assess the diurnal patterns, pollution hotspots and underlying factors driving changes. A pollution episode was observed early in January 2021, owing to new year celebration fireworks, when the daily average PM2.5 was around three-times the World Health Organisation limit. PM2.5 and NO2 exceeded the threshold limits on 15 and 10 days, respectively, as the lockdown eased and the school reopened, despite the predominant wind direction often being away from the school towards the roads. The peak concentration levels for all pollutants occurred during morning drop-off hours; however, some weekends showed higher or comparable concentrations to those during weekdays. The strong disproportional Pearson correlation between CO and temperature demonstrated the possible contribution of local sources through biomass burning. The impact of lifting restrictions after removing the weather impact showed that the average pollution levels were low in the beginning and increased by up to 22.7 % and 4.2 % for PM2.5 and NO2, respectively, with complete easing of lockdown. The Prophet algorithm was implemented to develop a prediction model using an NO2 dataset that performed moderately (R2, 0.48) for a new monthly dataset. This study was able to build a local air pollution database at a school gate, which enabled an understanding of the air pollution variability across the year and allowed evidence-based mitigation strategies to be devised.
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Affiliation(s)
- Prashant Kumar
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, Surrey, United Kingdom; Institute for Sustainability, University of Surrey, Guildford GU2 7XH, Surrey, United Kingdom.
| | - Hamid Omidvarborna
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH, Surrey, United Kingdom
| | - Runming Yao
- School of The Built Environment, University of Reading, RG6 6DF, United Kingdom; Joint International Research Laboratory of Green Buildings and Built Environments (Ministry of Education), School of the Civil Engineering, Chongqing University, Chongqing 400045, China
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Kumar P, Rawat N, Tiwari A. Micro-characteristics of a naturally ventilated classroom air quality under varying air purifier placements. ENVIRONMENTAL RESEARCH 2023; 217:114849. [PMID: 36414109 DOI: 10.1016/j.envres.2022.114849] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 06/16/2023]
Abstract
A naturally-ventilated operational classroom was instrumented at 18 locations to assess spatial variations of classroom air pollution (CRAP), thermal comfort and ventilation indicators under 10 different scenarios (base scenario without air purifier (AP); three single AP scenarios; three scenarios with two APs at same locations; three scenarios with two APs at different locations). Unlike PM2.5, monitored PM10 and CO2 concentrations followed the diurnal occupancy profile. Highest vertical variation (38%) in CO2 was at the classroom entry zone at 40-300 cm height. CO2 increased until 225 cm before stratifying further. PM10 increased to highest levels at children sitting height (100 cm) before decreasing to adult breathing height (150 cm). Highest horizontal variations in CO2 (PM10) were 29% (22%) at 40 cm height between the entry and occupied zones. Teachers' exposure to CO2 (PM10) in breathing zone varied by up to 6% (3%); the corresponding variations across monitored locations were up to 14% (19%). Teachers' exposure to CO2 was up to 13% higher than that of children and 18% lower for PM10. Traffic emissions (PM2.5 and NOx), secondary pollutants (VOCs and O3), thermal comfort parameters and noise level in the classroom varied insignificantly among scenarios. PM10 reduction was not doubled by using two air purifiers, which were most effective when placed within the highest PM concentration zone. Cross-comparisons of scenarios showed: use of AP reduced classroom's spatial average PM10 up to 14%; PM10 was reduced by increasing the AP's filtration capacity; and AP had insignificant impact on spatial average CO2. PM10 showed a maximum reduction of 46% (teacher zone), 62% (occupied zone) and 50% (entry zone) at children's breathing height, depending on usage scenario. This study produced high-resolution data for validating the detailed numerical models for classrooms and informing decision-making on AP's placement to minimise children's exposure to CRAP and re-breathed CO2.
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Affiliation(s)
- Prashant Kumar
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, United Kingdom; Institute for Sustainability, University of Surrey, Guildford GU2 7XH, Surrey, United Kingdom.
| | - Nidhi Rawat
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, United Kingdom
| | - Arvind Tiwari
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, Surrey, United Kingdom
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Peng S, Li G, Lin Y, Guo X, Xu H, Qiu W, Zhu H, Zheng J, Sun W, Hu X, Zhang G, Li B, Pathak JL, Bi X, Dai J. Stability of SARS-CoV-2 in cold-chain transportation environments and the efficacy of disinfection measures. Front Cell Infect Microbiol 2023; 13:1170505. [PMID: 37153150 PMCID: PMC10154586 DOI: 10.3389/fcimb.2023.1170505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 03/29/2023] [Indexed: 05/09/2023] Open
Abstract
Background Low temperature is conducive to the survival of COVID-19. Some studies suggest that cold-chain environment may prolong the survival of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and increase the risk of transmission. However, the effect of cold-chain environmental factors and packaging materials on SARS-CoV-2 stability remains unclear. Methods This study aimed to reveal cold-chain environmental factors that preserve the stability of SARS-CoV-2 and further explore effective disinfection measures for SARS-CoV-2 in the cold-chain environment. The decay rate of SARS-CoV-2 pseudovirus in the cold-chain environment, on various types of packaging material surfaces, i.e., polyethylene plastic, stainless steel, Teflon and cardboard, and in frozen seawater was investigated. The influence of visible light (wavelength 450 nm-780 nm) and airflow on the stability of SARS-CoV-2 pseudovirus at -18°C was subsequently assessed. Results Experimental data show that SARS-CoV-2 pseudovirus decayed more rapidly on porous cardboard surfaces than on nonporous surfaces, including polyethylene (PE) plastic, stainless steel, and Teflon. Compared with that at 25°C, the decay rate of SARS-CoV-2 pseudovirus was significantly lower at low temperatures. Seawater preserved viral stability both at -18°C and with repeated freeze-thaw cycles compared with that in deionized water. Visible light from light-emitting diode (LED) illumination and airflow at -18°C reduced SARS-CoV-2 pseudovirus stability. Conclusion Our studies indicate that temperature and seawater in the cold chain are risk factors for SARS-CoV-2 transmission, and LED visible light irradiation and increased airflow may be used as disinfection measures for SARS-CoV-2 in the cold-chain environment.
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Affiliation(s)
- Shuyi Peng
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Guojie Li
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Yuyin Lin
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People’s Hospital, Qingyuan, China
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, Guangzhou, China
| | - Xiaolan Guo
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People’s Hospital, Qingyuan, China
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Hao Xu
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Wenxi Qiu
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Huijuan Zhu
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jiaying Zheng
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Wei Sun
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
| | - Xiaodong Hu
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
| | - Guohua Zhang
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
| | - Bing Li
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People’s Hospital, Qingyuan, China
| | - Janak L. Pathak
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
- *Correspondence: Jianwei Dai, ; Xinhui Bi, ; Janak L. Pathak,
| | - Xinhui Bi
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
- *Correspondence: Jianwei Dai, ; Xinhui Bi, ; Janak L. Pathak,
| | - Jianwei Dai
- GMU-GIBH Joint School of Life Sciences, The Guangdong-Hong Kong-Macau Joint Laboratory for Cell Fate Regulation and Diseases, The State Key Lab of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People’s Hospital, Qingyuan, China
- Key Laboratory for Major Obstetric Diseases of Guangdong Province, Guangzhou, China
- Key Laboratory of Reproduction and Genetics of Guangdong Higher Education Institutes, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- *Correspondence: Jianwei Dai, ; Xinhui Bi, ; Janak L. Pathak,
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Ren C, Haghighat F, Feng Z, Kumar P, Cao SJ. Impact of ionizers on prevention of airborne infection in classroom. BUILDING SIMULATION 2022; 16:749-764. [PMID: 36474607 PMCID: PMC9716175 DOI: 10.1007/s12273-022-0959-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 10/12/2022] [Accepted: 10/31/2022] [Indexed: 06/17/2023]
Abstract
UNLABELLED Infectious diseases (e.g., coronavirus disease 2019) dramatically impact human life, economy and social development. Exploring the low-cost and energy-saving approaches is essential in removing infectious virus particles from indoors, such as in classrooms. The application of air purification devices, such as negative ion generators (ionizers), gains popularity because of the favorable removal capacity for particles and the low operation cost. However, small and portable ionizers have potential disadvantages in the removal efficiency owing to the limited horizontal diffusion of negative ions. This study aims to investigate the layout strategy (number and location) of ionizers based on the energy-efficient natural ventilation in the classroom to improve removal efficiency (negative ions to particles) and decrease infection risk. Three infected students were considered in the classroom. The simulations of negative ion and particle concentrations were performed and validated by the experiment. Results showed that as the number of ionizers was 4 and 5, the removal performance was largely improved by combining ionizer with natural ventilation. Compared with the scenario without an ionizer, the scenario with 5 ionizers largely increased the average removal efficiency from around 20% to 85% and decreased the average infection risk by 23%. The setup with 5 ionizers placed upstream of the classroom was determined as the optimal layout strategy, particularly when the location and number of the infected students were unknown. This work can provide a guideline for applying ionizers to public buildings when natural ventilation is used. ELECTRONIC SUPPLEMENTARY MATERIAL ESM the Appendix is available in the online version of this article at 10.1007/s12273-022-0959-z.
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Affiliation(s)
- Chen Ren
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096 China
| | - Fariborz Haghighat
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096 China
- Energy and Environment Group, Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, H3G 1M8 Canada
| | - Zhuangbo Feng
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096 China
| | - Prashant Kumar
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096 China
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil & Environmental Engineering, Faculty of Engineering & Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH UK
- Institute for Sustainability, University of Surrey, Guildford, Surrey, GU2 7XH UK
| | - Shi-Jie Cao
- School of Architecture, Southeast University, 2 Sipailou, Nanjing, 210096 China
- Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil & Environmental Engineering, Faculty of Engineering & Physical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH UK
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Takamure K, Sakamoto Y, Iwatani Y, Amano H, Yagi T, Uchiyama T. Characteristics of collection and inactivation of virus in air flowing inside a winding conduit equipped with 280 nm deep UV-LEDs. ENVIRONMENT INTERNATIONAL 2022; 170:107580. [PMID: 36252438 DOI: 10.1016/j.envint.2022.107580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
A general-purpose virus inactivation unit that can inactivate viruses was developed using deep ultraviolet (DUV) LEDs that emit DUV rays with a wavelength of 280 nm. The inside of the virus inactivation unit is a rectangular conduit with a sharp turn of 180° (sharp-turned rectangular conduit). Virus inactivation is attempted by directly irradiating the air passing through the conduit with DUV rays. The flow characteristics of air and virus particles inside the virus inactivation unit were investigated using numerical simulations. The air was locally accelerated at the sharp turn parts and flowed along the partition plate in the sharp-turned rectangular conduit. The aerosol particles moving in the sharp-turned rectangular conduit were greatly bent in orbit at the sharp turn parts, and then rapidly approached the partition plate at the lower part of the conduit. Consequently, many particles collided with the partition plates behind the sharp-turn parts. SARS-CoV-2 virus was nebulized in the virus inactivation unit, and the RNA concentration and virus inactivation rate with and without the emission of DUV-LEDs were measured in the experiment. The concentration of SARS-CoV-2 RNA was reduced to 60% through DUV-LED irradiation. In addition, SARS-CoV-2 passing through the virus inactivation unit was inactivated below the detection limit by the emission of DUV-LEDs. The virus inactivation rate and the value of the detection limit corresponded to 99.38% and 35.36 TCID50/mL, respectively.
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Affiliation(s)
- Kotaro Takamure
- Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| | - Yasuaki Sakamoto
- Graduate School of Informatics, Nagoya University, Nagoya 464-8601, Japan
| | - Yasumasa Iwatani
- Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya 460-0001, Japan.
| | - Hiroshi Amano
- Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| | - Tetsuya Yagi
- Department of Infectious Diseases, Nagoya University Hospital, Nagoya 466-0065, Japan.
| | - Tomomi Uchiyama
- Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
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Kvasnicka J, Cohen Hubal EA, Siegel JA, Scott JA, Diamond ML. Modeling Clothing as a Vector for Transporting Airborne Particles and Pathogens across Indoor Microenvironments. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:5641-5652. [PMID: 35404579 PMCID: PMC9069698 DOI: 10.1021/acs.est.1c08342] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/19/2022] [Accepted: 03/21/2022] [Indexed: 06/14/2023]
Abstract
Evidence suggests that human exposure to airborne particles and associated contaminants, including respiratory pathogens, can persist beyond a single microenvironment. By accumulating such contaminants from air, clothing may function as a transport vector and source of "secondary exposure". To investigate this function, a novel microenvironmental exposure modeling framework (ABICAM) was developed. This framework was applied to a para-occupational exposure scenario involving the deposition of viable SARS-CoV-2 in respiratory particles (0.5-20 μm) from a primary source onto clothing in a nonhealthcare setting and subsequent resuspension and secondary exposure in a car and home. Variability was assessed through Monte Carlo simulations. The total volume of infectious particles on the occupant's clothing immediately after work was 4800 μm3 (5th-95th percentiles: 870-32 000 μm3). This value was 61% (5-95%: 17-300%) of the occupant's primary inhalation exposure in the workplace while unmasked. By arrival at the occupant's home after a car commute, relatively rapid viral inactivation on cotton clothing had reduced the infectious volume on clothing by 80% (5-95%: 26-99%). Secondary inhalation exposure (after work) was low in the absence of close proximity and physical contact with contaminated clothing. In comparison, the average primary inhalation exposure in the workplace was higher by about 2-3 orders of magnitude. It remains theoretically possible that resuspension and physical contact with contaminated clothing can occasionally transmit SARS-CoV-2 between humans.
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Affiliation(s)
- Jacob Kvasnicka
- Department
of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada
| | - Elaine A. Cohen Hubal
- Center
for Public Health and Environmental Assessment, U.S. Environmental Protection Agency, Durham, North Carolina 27711, United States
| | - Jeffrey A. Siegel
- Department
of Civil and Mineral Engineering, University
of Toronto, Toronto, Ontario M5S 1A4, Canada
- Dalla
Lana School of Public Health, University
of Toronto, Toronto, Ontario M5T 3M7, Canada
| | - James A. Scott
- Dalla
Lana School of Public Health, University
of Toronto, Toronto, Ontario M5T 3M7, Canada
- Department
of Laboratory Medicine and Pathobiology, Temerty Faculty of Medicine, University of Toronto, 1 King’s College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Miriam L. Diamond
- Department
of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada
- Dalla
Lana School of Public Health, University
of Toronto, Toronto, Ontario M5T 3M7, Canada
- School of
the Environment, University of Toronto, Toronto, Ontario M5S 3E8, Canada
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Querol X, Alastuey A, Moreno N, Minguillón MC, Moreno T, Karanasiou A, Jimenez JL, Li Y, Morguí JA, Felisi JM. How can ventilation be improved on public transportation buses? Insights from CO 2 measurements. ENVIRONMENTAL RESEARCH 2022; 205:112451. [PMID: 34848209 DOI: 10.1016/j.envres.2021.112451] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/16/2021] [Accepted: 11/24/2021] [Indexed: 05/24/2023]
Abstract
Measurements of CO2 and counting of occupants were carried out in 37 public bus trips during commuting rush hours in Barcelona (NE Spain) with the aim of evaluating parameters governing ventilation inside the vehicles and proposing actions to improve it. The results show that CO2 concentrations (1039 and 934 ± 386 ppm, as average and median, during rush hours but with average reduced occupancy due to the fair to be infected by SARS-CoV-2 during the measurement period, and measured in the middle of the busses) are in the lower range of values recorded in the literature for public buses, however an improvement in ventilation is required in a significant proportion of the journeys. Thus, we found better ventilation in the older Euro 3+ (retrofitted with filter traps and selective catalytic reduction) and Euro 5 buses (average 918 ± 257 ppm) than in the hermetically closed new Euro 6 ones (1111 ± 432 ppm). The opening of the windows in the older buses yielded higher ventilation rates (778 ± 432 ppm). The opening of all doors at all stops increases the ventilation by causing a fall in concentrations of 200-350 ppm below inter-stop concentrations, with this effect typically lasting 40-50 s in the hermetically closed new Euro 6 hybrid buses. Based on these results a number of recommendations are offered in order to improve ventilation, including measurement of CO2 and occupancy, and installation of ventilation fans on the top of the hermetically closed new buses, introducing outdoor air when a given concentration threshold is exceeded. In these cases, a CO2 sensor installed in the outdoor air intake is also recommended to take into account external CO2 contributions.
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Affiliation(s)
- Xavier Querol
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Spain.
| | - Andrés Alastuey
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Spain
| | - Natalia Moreno
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Spain
| | - Maria Cruz Minguillón
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Spain
| | - Teresa Moreno
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Spain
| | - Angeliki Karanasiou
- Institute of Environmental Assessment and Water Research (IDAEA, CSIC), Barcelona, Spain
| | - Jose Luis Jimenez
- Department of Chemistry and Cooperative Institute for Research in the Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
| | - Josep Antoni Morguí
- Departament de Biología Evolutiva, Ecología i Ciencies Ambientals, Universitat de Barcelona (DBEECA, UB), Barcelona, Spain
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