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Mao N, Zhang D, Li Y, Li Y, Li J, Zhao L, Wang Q, Cheng Z, Zhang Y, Long E. How do temperature, humidity, and air saturation state affect the COVID-19 transmission risk? ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:3644-3658. [PMID: 35951241 PMCID: PMC9366825 DOI: 10.1007/s11356-022-21766-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/27/2022] [Indexed: 05/10/2023]
Abstract
Environmental parameters have a significant impact on the spread of respiratory viral diseases (temperature (T), relative humidity (RH), and air saturation state). T and RH are strongly correlated with viral inactivation in the air, whereas supersaturated air can promote droplet deposition in the respiratory tract. This study introduces a new concept, the dynamic virus deposition ratio (α), that reflects the dynamic changes in viral inactivation and droplet deposition under varying ambient environments. A non-steady-state-modified Wells-Riley model is established to predict the infection risk of shared air space and highlight the high-risk environmental conditions. Findings reveal that a rise in T would significantly reduce the transmission of COVID-19 in the cold season, while the effect is not significant in the hot season. The infection risk under low-T and high-RH conditions, such as the frozen seafood market, is substantially underestimated, which should be taken seriously. The study encourages selected containment measures against high-risk environmental conditions and cross-discipline management in the public health crisis based on meteorology, government, and medical research.
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Affiliation(s)
- Ning Mao
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute of Disaster Management and Reconstruction, Sichuan University, Chengdu, China
| | - Dingkun Zhang
- Laboratory of Clinical Proteomics and Metabolomics, Institutes for Systems Genetics, West China Hospital, Sichuan University, Chengdu, China
| | - Yupei Li
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute of Disaster Management and Reconstruction, Sichuan University, Chengdu, China
| | - Ying Li
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Jin Li
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Li Zhao
- China Academy of Building Research, Beijing, China
| | - Qingqin Wang
- China Academy of Building Research, Beijing, China
| | - Zhu Cheng
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Yin Zhang
- College of Architecture and Environment, Sichuan University, Chengdu, China
| | - Enshen Long
- MOE Key Laboratory of Deep Earth Science and Engineering, Institute of Disaster Management and Reconstruction, Sichuan University, Chengdu, China
- College of Architecture and Environment, Sichuan University, Chengdu, China
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Jia W, Wei J, Cheng P, Wang Q, Li Y. Exposure and respiratory infection risk via the short-range airborne route. BUILDING AND ENVIRONMENT 2022; 219:109166. [PMID: 35574565 PMCID: PMC9085449 DOI: 10.1016/j.buildenv.2022.109166] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/16/2022] [Accepted: 05/02/2022] [Indexed: 05/09/2023]
Abstract
Leading health authorities have suggested short-range airborne transmission as a major route of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). However, there is no simple method to assess the short-range airborne infection risk or identify its governing parameters. We proposed a short-range airborne infection risk assessment model based on the continuum model and two-stage jet model. The effects of ventilation, physical distance and activity intensity on the short-range airborne exposure were studied systematically. The results suggested that increasing physical distance and ventilation reduced short-range airborne exposure and infection risk. However, a diminishing return phenomenon was observed when the ventilation rate or physical distance was beyond a certain threshold. When the infectious quantum concentration was less than 1 quantum/L at the mouth, our newly defined threshold distance and threshold ventilation rate were independent of quantum concentration. We estimated threshold distances of 0.59, 1.1, 1.7 and 2.6 m for sedentary/passive, light, moderate and intense activities, respectively. At these distances, the threshold ventilation was estimated to be 8, 20, 43, and 83 L/s per person, respectively. The findings show that both physical distancing and adequate ventilation are essential for minimising infection risk, especially in high-intensity activity or densely populated spaces.
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Affiliation(s)
- Wei Jia
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Jianjian Wei
- Institute of Refrigeration and Cryogenics/Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province, Zhejiang University, Hangzhou, China
| | - Pan Cheng
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Qun Wang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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Kong M, Li L, Eilts SM, Li L, Hogan CJ, Pope ZC. Localized and Whole-Room Effects of Portable Air Filtration Units on Aerosol Particle Deposition and Concentration in a Classroom Environment. ACS ES&T ENGINEERING 2022; 2:653-669. [PMID: 37552723 PMCID: PMC8864773 DOI: 10.1021/acsestengg.1c00321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 05/14/2023]
Abstract
In indoor environments with limited ventilation, recirculating portable air filtration (PAF) units may reduce COVID-19 infection risk via not only the direct aerosol route (i.e., inhalation) but also via an indirect aerosol route (i.e., contact with the surface where aerosol particles deposited). We systematically investigated the impact of PAF units in a mock classroom, as a supplement to background ventilation, on localized and whole-room surface deposition and particle concentration. Fluorescently tagged particles with a volumetric mean diameter near 2 μm were continuously introduced into the classroom environment via a breathing simulator with a prescribed inhalation-exhalation waveform. Deposition velocities were inferred on >50 horizontal and vertical surfaces throughout the classroom, while aerosol concentrations were spatially monitored via optical particle spectrometry. Results revealed a particle decay rate consistent with expectations based upon the reported clean air delivery rates of the PAF units. Additionally, the PAF units reduced peak concentrations by a factor of around 2.5 compared to the highest concentrations observed and led to a statistically significant reduction in deposition velocities for horizontal surfaces >2.5 m from the aerosol source. Our results not only confirm that PAF units can reduce particle concentrations but also demonstrate that they may lead to reduced particle deposition throughout an indoor environment when properly positioned with respect to the location of the particle source(s) within the room (e.g., where the largest group of students sit) and the predominant air distribution profile of the room.
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Affiliation(s)
- Meng Kong
- Well Living Lab, Rochester,
Minnesota 55902, United States
| | - Linhao Li
- Well Living Lab, Rochester,
Minnesota 55902, United States
| | - Stephanie M. Eilts
- Department of Mechanical Engineering,
University of Minnesota, Minneapolis, Minnesota 55455,
United States
| | - Li Li
- Department of Mechanical Engineering,
University of Minnesota, Minneapolis, Minnesota 55455,
United States
| | - Christopher J. Hogan
- Department of Mechanical Engineering,
University of Minnesota, Minneapolis, Minnesota 55455,
United States
| | - Zachary C. Pope
- Well Living Lab, Rochester,
Minnesota 55902, United States
- Mayo Clinic, Department of Physiology and
Biomedical Engineering, Rochester, Minnesota 55905, United
States
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Peimbert M, Alcaraz LD. Where environmental microbiome meets its host: subway and passenger microbiome relationships. Mol Ecol 2022; 32:2602-2618. [PMID: 35318755 DOI: 10.1111/mec.16440] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 03/12/2022] [Accepted: 03/16/2022] [Indexed: 12/17/2022]
Abstract
Subways are urban transport systems with high capacity. Every day around the world, there are more than 150 million subway passengers. Since 2013, thousands of microbiome samples from various subways worldwide have been sequenced. Skin bacteria and environmental organisms dominate the subway microbiomes. The literature has revealed common bacterial groups in subway systems; even so, it is possible to identify cities by their microbiome. Low-frequency bacteria are responsible for specific bacterial fingerprints of each subway system. Furthermore, daily subway commuters leave their microbial clouds and interact with other passengers. Microbial exchange is quite fast; the hand microbiome changes within minutes, and after cleaning the handrails, the bacteria are re-established within minutes. To investigate new taxa and metabolic pathways of subway microbial communities, several high-quality metagenomic-assembled genomes (MAG) have been described. Subways are harsh environments unfavorable for microorganism growth. However, recent studies have observed a wide diversity of viable and metabolically active bacteria. Understanding which bacteria are living, dormant, or dead allows us to propose realistic ecological interactions. Questions regarding the relationship between humans and the subway microbiome, particularly the microbiome effects on personal and public health, remain unanswered. This review summarizes our knowledge of subway microbiomes and their relationship with passenger microbiomes.
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Affiliation(s)
- Mariana Peimbert
- Departamento de Ciencias Naturales, Unidad Cuajimalpa, Universidad Autónoma Metropolitana. Ciudad de México, México
| | - Luis D Alcaraz
- Departamento de Biología Celular, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México, México
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Fierce L, Robey AJ, Hamilton C. High efficacy of layered controls for reducing exposure to airborne pathogens. INDOOR AIR 2022; 32:e12989. [PMID: 35225391 DOI: 10.1111/ina.12989] [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: 08/18/2021] [Revised: 12/19/2021] [Accepted: 01/08/2022] [Indexed: 06/14/2023]
Abstract
To optimize strategies for curbing the transmission of airborne pathogens, the efficacy of three key controls-face masks, ventilation, and physical distancing-must be well understood. In this study, we used the Quadrature-based model of Respiratory Aerosol and Droplets to quantify the reduction in exposure to airborne pathogens from various combinations of controls. For each combination of controls, we simulated thousands of scenarios that represent the tremendous variability in factors governing airborne transmission and the efficacy of mitigation strategies. While the efficacy of any individual control was highly variable among scenarios, combining universal mask-wearing with distancing of 1 m or more reduced the median exposure by more than 99% relative to a close, unmasked conversation, with further reductions if ventilation is also enhanced. The large reductions in exposure to airborne pathogens translated to large reductions in the risk of initial infection in a new host. These findings suggest that layering controls is highly effective for reducing transmission of airborne pathogens and will be critical for curbing outbreaks of novel viruses in the future.
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Affiliation(s)
- Laura Fierce
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington, USA
- Environmental & Climate Sciences Department, Brookhaven National Laboratory, Upton, New York, USA
| | - Alison J Robey
- Center for Environmental Studies, Williams College, Williamstown, Massachusetts, USA
| | - Cathrine Hamilton
- Department of Chemistry, Indiana University of Pennsylvania, Indiana, Pennsylvania, USA
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Sensitivity of airborne transmission of enveloped viruses to seasonal variation in indoor relative humidity. INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER 2022. [PMCID: PMC8659254 DOI: 10.1016/j.icheatmasstransfer.2021.105747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In temperate climates, the peak in infection rates of enveloped viruses during the winter is likely heightened by seasonal variation in relative humidity within indoor spaces. While these seasonal trends are established in influenza and human coronaviruses, the mechanisms driving this seasonality remain poorly understood. Relative humidity impacts the evaporation rate and equilibrium size of airborne particles, which in turn may impact particle removal rates and virion viability. However, the relative importance of these two processes is not known. Here we use the Quadrature-based model of Respiratory Aerosol and Droplets to explore whether the seasonal variation in enveloped viruses is driven by differences in particle removal rates or by differences in virion inactivation rates. Through a large ensemble of simulations, we found that dry indoor conditions typical of winter lead to slower virion inactivation than humid indoor conditions typical of summer; in poorly ventilated spaces, this reduction in inactivation rates increases the airborne concentration of active virions, but this effect was important to virion exposure only when the susceptible person was farther than 2 m downwind of the infectious person. On the other hand, the impact of relative humidity on particle settling velocity did not significantly affect the removal or travel distance of virus-laden particles, suggesting that relative humidity is more likely to affect seasonal transmission via inactivation rates than via particle removal.
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Mikszewski A, Stabile L, Buonanno G, Morawska L. The vaccination threshold for SARS-CoV-2 depends on the indoor setting and room ventilation. BMC Infect Dis 2021; 21:1193. [PMID: 34836502 PMCID: PMC8622112 DOI: 10.1186/s12879-021-06884-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 11/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Effective vaccines are now available for SARS-CoV-2 in the 2nd year of the COVID-19 pandemic, but there remains significant uncertainty surrounding the necessary vaccination rate to safely lift occupancy controls in public buildings and return to pre-pandemic norms. The aim of this paper is to estimate setting-specific vaccination thresholds for SARS-CoV-2 to prevent sustained community transmission using classical principles of airborne contagion modeling. We calculated the airborne infection risk in three settings, a classroom, prison cell block, and restaurant, at typical ventilation rates, and then the expected number of infections resulting from this risk at varying percentages of occupant immunity. RESULTS We estimate the setting-specific immunity threshold for control of wild-type SARS-CoV-2 to range from a low of 40% for a mechanically ventilation classroom to a high of 85% for a naturally ventilated restaurant. CONCLUSIONS If vaccination rates are limited to a theoretical minimum of approximately two-thirds of the population, enhanced ventilation above minimum standards for acceptable air quality is needed to reduce the frequency and severity of SARS-CoV-2 superspreading events in high-risk indoor environments.
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Affiliation(s)
- A Mikszewski
- International Laboratory for Air Quality and Health, Queensland University of Technology, 2 George Street, Brisbane, QLD, 4001, Australia
- CIUS Building Performance Lab, The City University of New York, New York, NY, 10001, USA
| | - L Stabile
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy
| | - G Buonanno
- International Laboratory for Air Quality and Health, Queensland University of Technology, 2 George Street, Brisbane, QLD, 4001, Australia
- Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, FR, Italy
| | - L Morawska
- International Laboratory for Air Quality and Health, Queensland University of Technology, 2 George Street, Brisbane, QLD, 4001, Australia.
- Global Centre for Clean Air Research (GCARE), Department of Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, UK.
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