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Yao G, Liu Z, Liu H, Jiang C, Li Y, Liu J, He J. Air disinfection performance of upper-room ultraviolet germicidal irradiation (UR-UVGI) system in a multi-compartment dental clinic. JOURNAL OF HAZARDOUS MATERIALS 2024; 477:135383. [PMID: 39094316 DOI: 10.1016/j.jhazmat.2024.135383] [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: 05/17/2024] [Revised: 07/27/2024] [Accepted: 07/29/2024] [Indexed: 08/04/2024]
Abstract
Multi-compartment dental clinics present significant airborne cross-infection risks. Upper-room ultraviolet germicidal irradiation (UR-UVGI) system have shown promise in preventing airborne pathogens, but its available application data are insufficient in multi-compartment dental clinics. Therefore, the UR-UVGI system's performance in a multi-compartment dental clinic was comprehensively evaluated in this study. The accuracy of the turbulence and drift flux models was verified by experimental data from ultrasonic scaling. The effects of the ventilation rate, irradiation zone volume, and irradiation flux on UR-UVGI performance were analyzed using computational fluid dynamics coupled with a UV inactivation model. Different patient numbers were considered. The results showed that UR-UVGI significantly reduced virus concentrations and outperformed increased ventilation rates alone. At a ventilation rate of six air changes per hour (ACH), UR-UVGI with an irradiation zone volume of 20% and irradiation flux of 5 μW/cm2 achieved a 70.44% average virus reduction in the whole room (WR), outperforming the impact of doubling the ventilation rate from 6 to 12 ACH without UR-UVGI. The highest disinfection efficiency of UR-UVGI decreased for WRs with more patients. The compartment treating patients exhibited significantly lower disinfection efficiency than others. Moreover, optimal UR-UVGI performance occurs at lower ventilation rates, achieving over 80% virus disinfection in WR. Additionally, exceeding an irradiation zone volume of 20% or an irradiation flux of 5 μW/cm2 notably reduces the improvement rates of UR-UVGI performance. These findings provide a scientific reference for strategically applying UR-UVGI in multi-compartment dental clinics.
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Affiliation(s)
- Guangpeng Yao
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei 071003, PR China
| | - Zhijian Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei 071003, PR China.
| | - Haiyang Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei 071003, PR China
| | - Chuan Jiang
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei 071003, PR China
| | - Yabin Li
- The Fifth Medical Center of PLA General Hospital, Beijing 100039, PR China
| | - Jia Liu
- The Fifth Medical Center of PLA General Hospital, Beijing 100039, PR China
| | - Junzhou He
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei 071003, PR China.
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Gonçalves Lomardo P, Nunes MC, Arriaga P, Antunes LA, Machado A, Quinelato V, Aguiar TRDS, Casado PL. Concern about the risk of aerosol contamination from ultrasonic scaler: a systematic review and meta-analysis. BMC Oral Health 2024; 24:417. [PMID: 38580933 PMCID: PMC10996079 DOI: 10.1186/s12903-024-03996-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 02/07/2024] [Indexed: 04/07/2024] Open
Abstract
BACKGROUND Many instruments used in dentistry are rotary, such as handpieces, water syringes, and ultrasonic scalers that produce aerosols. The spray created by these instruments can carry, in addition to water, droplets of saliva, blood, and microorganisms, which can pose a risk of infections for healthcare professionals and patients. Due to the COVID-19 pandemic, this gained attention. OBJECTIVE The aim was to carry out a systematic review of the evidence of the scope of the aerosol produced by ultrasonic scaler in environmental contamination and the influence of the use of intraoral suction reduction devices. DESIGN Scientific literature was searched until June 19, 2021 in 6 databases: Pubmed, EMBASE, Web of science, Scopus, Virtual Health Library and Cochrane Library, without restrictions on language or publication date. Studies that evaluated the range of the aerosol produced by ultrasonic scaler during scaling/prophylaxis and the control of environmental contamination generated by it with the use of low (LVE) and high (HVE) volume evacuation systems were included. RESULTS Of the 1893 potentially relevant articles, 5 of which were randomized controlled trials (RCTs). The meta-analysis of 3 RCTs showed that, even at different distances from the patient's oral cavity, there was a significant increase in airborne bacteria in the dental environment with the use of ultrasonic scaler. In contrast, when meta-analysis compared the use of HVE with LVE, there was no significant difference (P = 0.40/CI -0.71[-2.37, 0.95]) for aerosol produced in the environment. CONCLUSIONS There is an increase in the concentration of bioaerosol in the dental environment during the use of ultrasonic scaler in scaling/prophylaxis, reaching up to 2 m away from the patient's mouth and the use of LVE, HVE or a combination of different devices, can be effective in reducing air contamination in the dental environment, with no important difference between different types of suction devices.
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Affiliation(s)
- Priscilla Gonçalves Lomardo
- Department of Periodontology, School of Dentistry, Fluminense Federal University, Rua Mário Santos Braga, nº 28, Centro, Niterói, Rio de Janeiro, CEP 24040-110, Brazil
| | - Mariana Campello Nunes
- Department of Periodontology, School of Dentistry, Fluminense Federal University, Rua Mário Santos Braga, nº 28, Centro, Niterói, Rio de Janeiro, CEP 24040-110, Brazil
| | - Patrícia Arriaga
- Department of Periodontology, School of Dentistry, Fluminense Federal University, Rua Mário Santos Braga, nº 28, Centro, Niterói, Rio de Janeiro, CEP 24040-110, Brazil
| | - Lívia Azeredo Antunes
- Department of Specific Information, School of Dentistry, Fluminense Federal University, Dr. Silvio Henrique Braune Street, 22 - Centro, Nova Friburgo, RJ, 28625- 650, Brazil
| | - Aldir Machado
- Department of Periodontology, School of Dentistry, Fluminense Federal University, Rua Mário Santos Braga, nº 28, Centro, Niterói, Rio de Janeiro, CEP 24040-110, Brazil
| | - Valquiria Quinelato
- National Institute of Traumatology and Orthopedics, Research department, Rio de Janeiro, Brazil.
| | - Telma Regina da Silva Aguiar
- Department of Periodontology, School of Dentistry, Fluminense Federal University, Rua Mário Santos Braga, nº 28, Centro, Niterói, Rio de Janeiro, CEP 24040-110, Brazil
| | - Priscila Ladeira Casado
- Department of Periodontology, School of Dentistry, Fluminense Federal University, Rua Mário Santos Braga, nº 28, Centro, Niterói, Rio de Janeiro, CEP 24040-110, Brazil
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Yu Y, Wu X, Sun Y. Precise control of digital dental unit to reduce aerosol and splatter production: new challenges for future epidemics. BMC Oral Health 2024; 24:213. [PMID: 38341576 PMCID: PMC10859011 DOI: 10.1186/s12903-024-03980-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 02/03/2024] [Indexed: 02/12/2024] Open
Abstract
BACKGROUND During dental procedures, critical parameters, such as cooling condition, speed of the rotary dental turbine (handpiece), and distance and angle from pollution sources, were evaluated for transmission risk of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), simulated by spiking in a plasmid encoding a modified viral spike protein, HexaPro (S6P), in droplets and aerosols. METHODS To simulate routine operation in dental clinics, dental procedures were conducted on a dental manikin within a digital dental unit, incorporating different dental handpiece speeds and cooling conditions. The tooth model was immersed in Coomassie brilliant blue dye and was pre-coated with 100 μL water spiked-in with S6P-encoding plasmid. Furthermore, the manikin was surrounded by filter papers and Petri dishes positioned at different distances and angles. Subsequently, the filter papers and Petri dishes were collected to evaluate the aerosol splash points and the viral load of S6P-encoding plasmid in aerosols and splatters generated during the dental procedure. RESULTS Aerosol splashing generated a localized pollution area extended up to 60 cm, with heightened contamination risks concentrated within a 30 cm radius. Significant differences in aerosol splash points and viral load by different turbine handpiece speeds under any cooling condition (P < 0.05) were detected. The highest level of aerosol splash points and viral load were observed when the handpiece speed was set at 40,000 rpm. Conversely, the lowest level of aerosol splash point and viral load were found at a handpiece speed of 10,000 rpm. Moreover, the aerosol splash points with higher viral load were more prominent in the positions of the operator and assistant compared to other positions. Additionally, the position of the operator exhibited the highest viral load among all positions. CONCLUSIONS To minimize the spread of aerosol and virus in clinics, dentists are supposed to adopt the minimal viable speed of a dental handpiece with limited cooling water during dental procedures. In addition, comprehensive personal protective equipment is necessary for both dental providers and dental assistants.
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Affiliation(s)
- Yuedi Yu
- College of Dental Medicine, Columbia University, New York, NY, 10032, USA
| | - Xueling Wu
- Aaron Diamond AIDS Research Center, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, 10032, USA
| | - Yang Sun
- Department of Stomatology, Zhongshan Hospital, Fudan University, No. 180 Fenglin road, Shanghai, 200032, China.
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He J, Li J, Chen B, Yang W, Yu X, Zhang F, Li Y, Shu H, Zhu X. Study of aerosol dispersion and control in dental practice. Clin Oral Investig 2024; 28:120. [PMID: 38280059 DOI: 10.1007/s00784-024-05524-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 01/19/2024] [Indexed: 01/29/2024]
Abstract
OBJECTIVES In this study, we investigated the dispersion patterns of aerosols and droplets in dental clinics and developed a suction device to evaluate its effectiveness in reducing aerosols during dental procedures. MATERIALS AND METHODS Firstly, the continuous images of oral aerosols and droplets were photographed with a high-speed camera, and the trajectories of these particles were recognized and processed by Image J to determine key parameters affecting particle dispersion: diffusion velocity, distance, and angle. Secondly, based on the parameter data, the flow field of aerosol particles around the oral cavity was simulated using computational fluid dynamics (CFD), and the flow field under adsorption conditions was simulated to demonstrate the aerodynamic characteristics and capture efficiencies of the single-channel and three-channel adsorption ports at different pressures. Finally, according to the simulated data, a three-channel suction device was developed, and the capture efficiency of the device was tested by the fluorescein tracer method. RESULTS The dispersion experimental data showed that aerosol particles' maximum diffusion velocity, distance, and angle were 6.2 m/s, 0.55 m, and 130°, respectively. The simulated aerosol flow-field distribution was consistent with the aerosol dispersion patterns. The adsorption simulation results showed that the outlet flow rate of single-channel adsorption was 184.5 L/s at - 350 Pa, and the aerosol capture efficiency could reach 79.4%. At - 350 Pa and - 150 Pa, the outlet flow rate of three-channel adsorption was 228.9 L/s, and the capture efficiency was 99.23%. The adsorption experimental data showed that the capture efficiency of three-channel suction device was 97.71%. CONCLUSIONS A three-channel suction device was designed by simulations and experiments, which can capture most aerosols in the dental clinic and prevent them from spreading. CLINICAL RELEVANCE Using three-channel suction devices during oral treatment effectively reduces the spread of oral aerosols, which is essential to prevent the spread of epidemics and ensure the health and safety of patients and dental staff.
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Affiliation(s)
- Junjie He
- School of Mechanical Engineering, Guizhou University, Guiyang, Guizhou, China
| | - Jiachun Li
- School of Mechanical Engineering, Guizhou University, Guiyang, Guizhou, China.
| | - Bo Chen
- School of Mechanical Engineering, Guizhou University, Guiyang, Guizhou, China
| | - Wei Yang
- School of Medicine, Guizhou University, Guiyang, Guizhou, China
| | - Xiaoyan Yu
- Guiyang Stomatological Hospital, Guiyang, Guizhou, China
| | - Fan Zhang
- School of Mechanical Engineering, Guizhou University, Guiyang, Guizhou, China
| | - Yugang Li
- School of Mechanical Engineering, Guizhou University, Guiyang, Guizhou, China
| | - Haiyin Shu
- School of Medicine, Guizhou University, Guiyang, Guizhou, China
| | - Xiankun Zhu
- Guiyang Stomatological Hospital, Guiyang, Guizhou, China
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Watanabe J, Iwamatsu-Kobayashi Y, Kikuchi K, Kajita T, Morishima H, Yamauchi K, Yashiro W, Nishimura H, Kanetaka H, Egusa H. Visualization of droplets and aerosols in simulated dental treatments to clarify the effectiveness of oral suction devices. J Prosthodont Res 2024; 68:85-91. [PMID: 36823102 DOI: 10.2186/jpr.jpr_d_23_00013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
PURPOSE The hazards of aerosols generated during dental treatments are poorly understood. This study aimed to establish visualization methods, discover conditions for droplets/aerosols generated in simulating dental treatments and identify the conditions for effective suction methods. METHODS The spreading area was evaluated via image analysis of the droplets/aerosols generated by a dental air turbine on a mannequin using a light emitting diode (LED) light source and high-speed camera. The effects of different bur types and treatment sites, reduction effect of intra-oral suction (IOS) and extra-oral suction (EOS) devices, and effect of EOS installation conditions were evaluated. RESULTS Regarding the bur types, a bud-shaped bur on the air turbine generated the most droplets/aerosols compared with round-shaped, round end-tapered, or needle-tapered burs. Regarding the treatment site, the area of droplets/aerosols produced by an air turbine from the palatal plane of the anterior maxillary teeth was significantly higher. The generated droplet/aerosol area was reduced by 92.1% by using IOS alone and 97.8% by combining IOS and EOS. EOS most effectively aspirated droplets/aerosols when placed close (10 cm) to the mouth in the vertical direction (0°). CONCLUSIONS The droplets/aerosols generated by an air turbine could be visualized using an LED light and a high-speed camera in simulating dental treatments. The bur shape and position of the dental air turbine considerably influenced droplet/aerosol diffusion. The combined use of IOS and EOS at a proper position (close and perpendicular to the mouth) facilitated effective diffusion prevention to protect the dental-care environment.
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Affiliation(s)
- Jun Watanabe
- Division of Dental Safety and System Management, Tohoku University Hospital, Sendai
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai
| | - Yoko Iwamatsu-Kobayashi
- Division of Dental Safety and System Management, Tohoku University Hospital, Sendai
- Liaison Centre for Innovative Dentistry, Tohoku University Graduate School of Dentistry, Sendai
| | - Kenji Kikuchi
- Biological Flow Studies Laboratory, Department of Finemechanics, Graduate School of Engineering, Tohoku University, Sendai
| | - Tomonari Kajita
- Division of Oral and Maxillofacial Oncology and Surgical Sciences, Tohoku University Graduate School of Dentistry, Sendai
| | - Hiromitsu Morishima
- Division of Oral and Maxillofacial Reconstructive Surgery, Tohoku University Graduate School of Dentistry, Sendai
| | - Kensuke Yamauchi
- Division of Oral and Maxillofacial Reconstructive Surgery, Tohoku University Graduate School of Dentistry, Sendai
| | - Wataru Yashiro
- Next-Generation Detection System Smart Lab, International Center for Synchrotron Radiation Innovation Smart (SRIS), Tohoku University, Sendai
- Frontier Quantum-beam Metrology Laboratory, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai
- Department of Applied Physics, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, National Hospital Organization, Sendai
| | - Hiroyasu Kanetaka
- Liaison Centre for Innovative Dentistry, Tohoku University Graduate School of Dentistry, Sendai
| | - Hiroshi Egusa
- Division of Dental Safety and System Management, Tohoku University Hospital, Sendai
- Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Sendai
- Liaison Centre for Innovative Dentistry, Tohoku University Graduate School of Dentistry, Sendai
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Kusuluri R, Mirikar D, Palanivel S, Arumuru V. Risk assessment of airborne virus transmission in an intensive care unit due to single and sequential coughing. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2024; 44:54-69. [PMID: 37038233 DOI: 10.1111/risa.14133] [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: 08/16/2022] [Revised: 01/19/2023] [Accepted: 03/02/2023] [Indexed: 06/19/2023]
Abstract
The virus causing COVID-19 has constantly been mutating into new variants. Some of them are more transmissive and resistant to antibiotics. The current research article aims to examine the airborne transmission of the virus expelled by coughing action in a typical intensive care unit. Both single and sequential coughing actions have been considered to get closer to practical scenarios. The objective is to assess the effectiveness of air change per hour (ACH) on the risk of infection to a healthcare person and how the air change rate influences the dispersion of droplets. Such a study is seldom reported and has significant relevance. A total of four cases were analyzed, of which two were of sequential cough. When the ACH is changed from 6 to 12, the average particle residence time is reduced by ∼7 s. It is found that the risk of infection in the case of sequential cough will be relatively low compared to a single cough if the outlet of the indoor environment is placed above the patient's head. This arrangement also eliminates the requirement of higher ACH, which has significance from an energy conservation perspective.
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Affiliation(s)
- Rajendra Kusuluri
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, India
| | - Dnyanesh Mirikar
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, India
| | - Silambarasan Palanivel
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, India
| | - Venugopal Arumuru
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, India
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Desai R, Komperda J, Elnagar MH, Viana G, Galang-Boquiren MTS. Evaluation of upper airway characteristics in patients with and without sleep apnea using cone-beam computed tomography and computational fluid dynamics. Orthod Craniofac Res 2023; 26 Suppl 1:164-170. [PMID: 38009653 DOI: 10.1111/ocr.12728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 09/26/2023] [Accepted: 10/30/2023] [Indexed: 11/29/2023]
Abstract
OBJECTIVE To determine if upper airway characteristics and airway pressure change significantly between low risk, healthy non-OSA subjects, and OSA subjects during respiration using cone-beam computed tomography (CBCT) imaging and steady-state k-ω model computational fluid dynamics (CFD) fluid flow simulations, respectively. MATERIALS AND METHODS CBCT scans were collected at both end-inhalation and end-exhalation for 16 low-risk non-OSA subjects and compared to existing CBCT data from 7 OSA subjects. The CBCT images were imported into Dolphin Imaging and the upper airway was segmented into stereolithography (STL) files for area and volumetric measurements. Subject models that met pre-processing criteria underwent CFD simulations using ANSYS Fluent Meshing (Canonsburg, PA) in which unstructured mesh models were generated to solve the standard dual equation turbulence model (k-ω). Objective and supplemental descriptive measures were obtained and statistical analyses were performed with both parametric and non-parametric tests to evaluate statistical significance at P < .05. RESULTS Regarding area and volumetric assessments, there were statistically significant mean differences in Total Volume and Minimum CSA between non-OSA and OSA groups at inhalation and exhalation (P = .002, .003, .004, and .007), respectively. There were also statistically significant mean differences in volume and min CSA between the inhalation and exhalation for the non-OSA group (P < .001 and .002), respectively. CONCLUSION While analysis of the CFD simulation was limited by the collected data available, a finding consistent with published literature was that the OSA subject group simulation models depicted the point of lowest pressure coinciding with the area of maximum constriction.
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Affiliation(s)
- Raj Desai
- Department of Orthodontics, University of Illinois Chicago, Chicago, Illinois, USA
- Private Practice of Orthodontics, Chicago, Illinois, USA
| | - Jonathan Komperda
- Department of Mechanical and Industrial Engineering, University of Illinois Chicago, Chicago, Illinois, USA
| | - Mohammed H Elnagar
- Department of Orthodontics, University of Illinois Chicago, Chicago, Illinois, USA
| | - Grace Viana
- Department of Orthodontics, University of Illinois Chicago, Chicago, Illinois, USA
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Liu Z, Li H, Chu J, Huang Z, Xiao X, Wang Y, He J. The impact of high background particle concentration on the spatiotemporal distribution of Serratia marcescens bioaerosol. JOURNAL OF HAZARDOUS MATERIALS 2023; 458:131863. [PMID: 37354722 DOI: 10.1016/j.jhazmat.2023.131863] [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: 03/10/2023] [Revised: 06/07/2023] [Accepted: 06/13/2023] [Indexed: 06/26/2023]
Abstract
Airborne transmission is a well-established mode of dissemination for infectious diseases, particularly in closed environments. However, previous research has often overlooked the potential impact of background particle concentration on bioaerosol characteristics. We compared the spatial and temporal distributions of bioaerosols under two levels of background particle concentration: heavily polluted (150-250 μg/m3) and excellent (0-35 μg/m3) in a typical ward. Serratia marcescens bioaerosol was adopted as a bioaerosol tracer, and the bioaerosol concentrations were quantified using six-stage Andersen cascade impactors. The results showed a significant reduction (over at least 62.9%) in bioaerosol concentration under heavily polluted levels compared to excellent levels at all sampling points. The temporal analysis also revealed that the decay rate of bioaerosols was higher (at least 0.654 min-1) under heavily polluted levels compared to excellent levels. These findings suggest that background particles can facilitate bioaerosol removal, contradicting the assumption made in previous research that background particle has no effect on bioaerosol characteristics. Furthermore, we observed differences in the size distribution of bioaerosols between the two levels of background particle concentration. The average bioaerosols size under heavily polluted levels was found to be higher than that under excellent levels, and the average particle size under heavily polluted levels gradually increased with time. In conclusion, these results highlight the importance of considering background particle concentration in future research on bioaerosol characteristics.
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Affiliation(s)
- Zhijian Liu
- School of Energy and Power Engineering, North China Electric Power University, Baoding 071003, China
| | - Haochuan Li
- School of Energy and Power Engineering, North China Electric Power University, Baoding 071003, China
| | - Jiaqi Chu
- School of Energy and Power Engineering, North China Electric Power University, Baoding 071003, China
| | - Zhenzhe Huang
- School of Energy and Power Engineering, North China Electric Power University, Baoding 071003, China
| | - Xia Xiao
- School of Energy and Power Engineering, North China Electric Power University, Baoding 071003, China
| | - Yongxin Wang
- 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.
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Arumuru V, Kusuluri R, Mirikar D. Role of face masks and ventilation rates in mitigating respiratory disease transmission in ICU. Sci Rep 2023; 13:11124. [PMID: 37429928 DOI: 10.1038/s41598-023-38031-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 07/01/2023] [Indexed: 07/12/2023] Open
Abstract
Indoor environments are major contributing locations where the respiratory virus transmission occurs. Higher air change rate (ACH) values (up to 12) have been recommended in hospital environments to reduce virus transmission. In the present study, the Large Eddy Simulation (LES) data of particle transport in a typical intensive care unit (ICU) is used to calculate the infection risk in close proximity interaction. Three different ACH (6, 9, 12) rates with face masks and one case with a healthy person wearing a face shield are considered. The average resident time of the droplets in the ICU is calculated to find the optimal ACH rate. Of the different types of masks analyzed in the present study, the triple-layer mask has shown the most resistance ([Formula: see text] probability of infection) to the penetration of virus-laden droplets, while the single-layer mask has shown the highest risk of infection (up to [Formula: see text]. The results show that the ACH rate has little effect on close proximity transmission. The ACH 9 case provided optimal value for the particle removal, while the ACH 12 has inferior performance to that of ACH 9. From an energy consumption view, our results recommend not using higher ACH in similar indoor environments. Inside indoor environments, it is advised to wear a three-layer face mask and face shield to reduce the risk of infection.
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Affiliation(s)
- Venugopal Arumuru
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology, Bhubaneswar, 752050, India.
| | - Rajendra Kusuluri
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology, Bhubaneswar, 752050, India
| | - Dnyanesh Mirikar
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology, Bhubaneswar, 752050, India
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Nazari A, Taghizadeh-Hesary F. Numerical investigation of airborne infection risk in an elevator cabin under different ventilation designs. PHYSICS OF FLUIDS 2023; 35. [DOI: 10.1063/5.0152878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
Airborne transmission of SARS-CoV-2 via virus-laden aerosols in enclosed spaces poses a significant concern. Elevators, commonly utilized enclosed spaces in modern tall buildings, present a challenge as the impact of varying heating, ventilation, and air conditioning (HVAC) systems on virus transmission within these cabins remains unclear. In this study, we employ computational modeling to examine aerosol transmission within an elevator cabin outfitted with diverse HVAC systems. Using a transport equation, we model aerosol concentration and assess infection risk distribution across passengers' breathing zones. We calculate the particle removal efficiency for each HVAC design and introduce a suppression effect criterion to evaluate the effectiveness of the HVAC systems. Our findings reveal that mixing ventilation, featuring both inlet and outlet at the ceiling, proves most efficient in reducing particle spread, achieving a maximum removal efficiency of 79.40% during the exposure time. Conversely, the stratum ventilation model attains a mere removal efficiency of 3.97%. These results underscore the importance of careful HVAC system selection in mitigating the risk of SARS-CoV-2 transmission within elevator cabins.
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Affiliation(s)
- Ata Nazari
- University of Tabriz, Department of Mechanical Engineering 1 , Tabriz, Iran
| | - Farzad Taghizadeh-Hesary
- ENT and Head and Neck Research Center and Department, The Five Senses Health Institute, School of Medicine, Iran University of Medical Sciences 5 , Tehran, Iran
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A review on indoor airborne transmission of COVID-19– modelling and mitigation approaches. JOURNAL OF BUILDING ENGINEERING 2023; 64:105599. [PMCID: PMC9699823 DOI: 10.1016/j.jobe.2022.105599] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/11/2022] [Accepted: 11/21/2022] [Indexed: 06/09/2023]
Abstract
In the past few years, significant efforts have been made to investigate the transmission of COVID-19. This paper provides a review of the COVID-19 airborne transmission modeling and mitigation strategies. The simulation models here are classified into airborne transmission infectious risk models and numerical approaches for spatiotemporal airborne transmissions. Mathematical descriptions and assumptions on which these models have been based are discussed. Input data used in previous simulation studies to assess the dispersion of COVID-19 are extracted and reported. Moreover, measurements performed to study the COVID-19 airborne transmission within indoor environments are introduced to support validations for anticipated future modeling studies. Transmission mitigation strategies recommended in recent studies have been classified to include modifying occupancy and ventilation operations, using filters and air purifiers, installing ultraviolet (UV) air disinfection systems, and personal protection compliance, such as wearing masks and social distancing. The application of mitigation strategies to various building types, such as educational, office, public, residential, and hospital, is reviewed. Recommendations for future works are also discussed based on the current apparent knowledge gaps covering both modeling and mitigation approaches. Our findings show that different transmission mitigation measures were recommended for various indoor environments; however, there is no conclusive work reporting their combined effects on the level of mitigation that may be achieved. Moreover, further studies should be conducted to understand better the balance between approaches to mitigating the viral transmissions in buildings and building energy consumption.
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Dey S, Tunio M, Boryc LC, Hodgson BD, Garcia GJM. Quantifying strategies to minimize aerosol dispersion in dental clinics. EXPERIMENTAL AND COMPUTATIONAL MULTIPHASE FLOW 2023; 5:290-303. [PMID: 37305074 PMCID: PMC10042415 DOI: 10.1007/s42757-022-0157-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 11/12/2022] [Accepted: 12/25/2022] [Indexed: 03/29/2023]
Abstract
Many dental procedures are aerosol-generating and pose a risk for the spread of airborne diseases, including COVID-19. Several aerosol mitigation strategies are available to reduce aerosol dispersion in dental clinics, such as increasing room ventilation and using extra-oral suction devices and high-efficiency particulate air (HEPA) filtration units. However, many questions remain unanswered, including what the optimal device flow rate is and how long after a patient exits the room it is safe to start treatment of the next patient. This study used computational fluid dynamics (CFD) to quantify the effectiveness of room ventilation, an HEPA filtration unit, and two extra-oral suction devices to reduce aerosols in a dental clinic. Aerosol concentration was quantified as the particulate matter under 10 µm (PM10) using the particle size distribution generated during dental drilling. The simulations considered a 15 min procedure followed by a 30 min resting period. The efficiency of aerosol mitigation strategies was quantified by the scrubbing time, defined as the amount of time required to remove 95% of the aerosol released during the dental procedure. When no aerosol mitigation strategy was applied, PM10 reached 30 µg/m3 after 15 min of dental drilling, and then declined gradually to 0.2 µg/m3 at the end of the resting period. The scrubbing time decreased from 20 to 5 min when the room ventilation increased from 6.3 to 18 air changes per hour (ACH), and decreased from 10 to 1 min when the flow rate of the HEPA filtration unit increased from 8 to 20 ACH. The CFD simulations also predicted that the extra-oral suction devices would capture 100% of the particles emanating from the patient's mouth for device flow rates above 400 L/min. In summary, this study demonstrates that aerosol mitigation strategies can effectively reduce aerosol concentrations in dental clinics, which is expected to reduce the risk of spreading COVID-19 and other airborne diseases.
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Affiliation(s)
- Shamudra Dey
- Joint Department of Biomedical Engineering, Marquette University, Medical College of Wisconsin, Milwaukee, 53226 USA
| | - Maryam Tunio
- School of Dentistry, Marquette University, Milwaukee, 53233 USA
| | - Louis C. Boryc
- School of Dentistry, Marquette University, Milwaukee, 53233 USA
| | | | - Guilherme J. M. Garcia
- Joint Department of Biomedical Engineering, Marquette University, Medical College of Wisconsin, Milwaukee, 53226 USA
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13
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Liu Z, Zhang P, Liu H, He J, Li Y, Yao G, Liu J, Lv M, Yang W. Estimating the restraint of SARS-CoV-2 spread using a conventional medical air-cleaning device: Based on an experiment in a typical dental clinical setting. Int J Hyg Environ Health 2023; 248:114120. [PMID: 36709744 PMCID: PMC9883001 DOI: 10.1016/j.ijheh.2023.114120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/14/2022] [Accepted: 01/24/2023] [Indexed: 01/28/2023]
Abstract
OBJECTIVES Droplets or aerosols loaded with SARS-CoV-2 can be released during breathing, coughing, or sneezing from COVID-19-infected persons. To investigate whether the most commonly applied air-cleaning device in dental clinics, the oral spray suction machine (OSSM), can provide protection to healthcare providers working in clinics against exposure to bioaerosols during dental treatment. METHOD In this study, we measured and characterized the temporal and spatial variations in bioaerosol concentration and deposition with and without the use of the OSSM using an experimental design in a dental clinic setting. Serratia marcescens (a bacterium) and ΦX174 phage (a virus) were used as tracers. The air sampling points were sampled using an Anderson six-stage sampler, and the surface-deposition sampling points were sampled using the natural sedimentation method. The Computational Fluid Dynamics method was adopted to simulate and visualize the effect of the OSSM on the concentration spatial distribution. RESULTS During dental treatment, the peak exposure concentration increased by up to 2-3 orders of magnitude (PFU/m3) for healthcare workers. Meanwhile, OSSM could lower the mean bioaerosol exposure concentration from 58.84 PFU/m3 to 4.10 PFU/m3 for a healthcare worker, thereby inhibiting droplet and airborne transmission. In terms of deposition, OSSM significantly reduced the bioaerosol surface concentration from 28.1 PFU/m3 to 2.5 PFU/m3 for a surface, effectively preventing fomite transmission. CONCLUSION The use of OSSM showed the potential to restraint the spread of bioaerosols in clinical settings. Our study demonstrates that OSSM use in dental clinics can reduce the exposure concentrations of bioaerosols for healthcare workers during dental treatment and is beneficial for minimizing the risk of infectious diseases such as COVID-19.
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Affiliation(s)
- Zhijian Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China.
| | - Peiwen Zhang
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Haiyang Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Junzhou He
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Yabin Li
- The Fifth Medical Center of People's Liberation Army of China General Hospital, Beijing, 100039, China
| | - Guangpeng Yao
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Jia Liu
- The Fifth Medical Center of People's Liberation Army of China General Hospital, Beijing, 100039, China
| | - Meng Lv
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Wenhui Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China.
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14
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Yang L, Iwami M, Chen Y, Wu M, van Dam KH. Computational decision-support tools for urban design to improve resilience against COVID-19 and other infectious diseases: A systematic review. PROGRESS IN PLANNING 2023; 168:100657. [PMID: 35280114 PMCID: PMC8904142 DOI: 10.1016/j.progress.2022.100657] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The COVID-19 pandemic highlighted the need for decision-support tools to help cities become more resilient to infectious diseases. Through urban design and planning, non-pharmaceutical interventions can be enabled, impelling behaviour change and facilitating the construction of lower risk buildings and public spaces. Computational tools, including computer simulation, statistical models, and artificial intelligence, have been used to support responses to the current pandemic as well as to the spread of previous infectious diseases. Our multidisciplinary research group systematically reviewed state-of-the-art literature to propose a toolkit that employs computational modelling for various interventions and urban design processes. We selected 109 out of 8,737 studies retrieved from databases and analysed them based on the pathogen type, transmission mode and phase, design intervention and process, as well as modelling methodology (method, goal, motivation, focus, and indication to urban design). We also explored the relationship between infectious disease and urban design, as well as computational modelling support, including specific models and parameters. The proposed toolkit will help designers, planners, and computer modellers to select relevant approaches for evaluating design decisions depending on the target disease, geographic context, design stages, and spatial and temporal scales. The findings herein can be regarded as stand-alone tools, particularly for fighting against COVID-19, or be incorporated into broader frameworks to help cities become more resilient to future disasters.
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Affiliation(s)
- Liu Yang
- School of Architecture, Southeast University, Nanjing, China
- Research Center of Urban Design, Southeast University, Nanjing, China
| | - Michiyo Iwami
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, UK
| | - Yishan Chen
- Architecture and Urban Design Research Center, China IPPR International Engineering CO., LTD, Beijing, China
| | - Mingbo Wu
- State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Koen H van Dam
- Centre for Process Systems Engineering, Department of Chemical Engineering, Imperial College London, UK
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15
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Liu Z, Yao G, Li Y, Huang Z, Jiang C, He J, Wu M, Liu J, Liu H. Bioaerosol distribution characteristics and potential SARS-CoV-2 infection risk in a multi-compartment dental clinic. BUILDING AND ENVIRONMENT 2022; 225:109624. [PMID: 36164582 PMCID: PMC9494923 DOI: 10.1016/j.buildenv.2022.109624] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 08/28/2022] [Accepted: 09/17/2022] [Indexed: 06/16/2023]
Abstract
Dental clinics have a potential risk of infection, particularly during the COVID-19 pandemic. Multi-compartment dental clinics are widely used in general hospitals and independent clinics. This study utilised computational fluid dynamics to investigate the bioaerosol distribution characteristics in a multi-compartment dental clinic through spatiotemporal distribution, working area time-varying concentrations, and key surface deposition. The infection probability of SARS-CoV-2 for the dental staff and patients was calculated using the Wells-Riley model. In addition, the accuracy of the numerical model was verified by field measurements of aerosol concentrations performed during a clinical ultrasonic scaling procedure. The results showed that bioaerosols were mainly distributed in the compartments where the patients were treated. The average infection probability was 3.8% for dental staff. The average deposition number per unit area of the treatment chair and table are 28729 pcs/m2 and 7945 pcs/m2, respectively, which creates a possible contact transmission risk. Moreover, there was a certain cross-infection risk in adjacent compartments, and the average infection probability for patients was 0.84%. The bioaerosol concentrations of the working area in each compartment 30 min post-treatment were reduced to 0.07% of those during treatment, and the infection probability was <0.05%. The results will contribute to an in-depth understanding of the infection risk in multi-compartment dental clinics, forming feasible suggestions for management to efficiently support epidemic prevention and control in dental clinics.
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Affiliation(s)
- Zhijian Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Guangpeng Yao
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Yabin Li
- The Fifth Medical Center of PLA General Hospital, Beijing, 100039, China
| | - Zhenzhe Huang
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Chuan Jiang
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Junzhou He
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Minnan Wu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
| | - Jia Liu
- The Fifth Medical Center of PLA General Hospital, Beijing, 100039, China
| | - Haiyang Liu
- Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China
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16
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Field Experiments to Identify and Eliminate Recirculation Zones to Improve Indoor Ventilation: Comparison with CFD. TRANSACTIONS OF THE INDIAN NATIONAL ACADEMY OF ENGINEERING 2022; 7:911-926. [PMID: 35836614 PMCID: PMC9098795 DOI: 10.1007/s41403-022-00335-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 04/15/2022] [Indexed: 11/28/2022]
Abstract
Ventilation of shared indoor spaces is crucial for mitigating air-borne infection spread among its occupants. Replacing the air in a room with fresh air is key to minimize the concentration of potentially infectious aerosol generated in the room. Recirculating air flow present at corners and around obstacles can trap air and infectious aerosol. This can significantly delay their evacuation by the ventilation system. Knowing the location and extent of such recirculation zones is, therefore, important. In this work, we present flow visualization experiments to identify recirculation zones in an enclosed space. It is based on the deflection of the smoke streak generated by an incense stick. We use particle image velocimetry (PIV) post-processing to quantify the deflection of the smoke streak and use it as an indicator of the direction of local air flow. Positive deflection, defined as the deflection towards the exit location, is associated with primary flow present in well-ventilated regions of the room. On the other hand, negative deflection indicates reversed flow in recirculation zones, where the smoke streak is defined away from the exit location. The technique is applied to a public shared washroom, where the toilet seat is found to be in a well-ventilated region, while the washbasin is in a large recirculation zone. We compare the experimental point measurements with flow field solution obtained using computational fluid dynamics (CFD). We also explore geometry modifications as a strategy to eliminate the recirculation zone over the washbasin.
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17
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Fennelly M, Gallagher C, Harding M, Hellebust S, Wenger J, O'Sullivan N, O'Connor D, Prentice M. Real-time Monitoring of Aerosol Generating Dental Procedures. J Dent 2022; 120:104092. [PMID: 35304203 DOI: 10.1016/j.jdent.2022.104092] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/04/2022] [Accepted: 03/09/2022] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE We aimed to quantify aerosol concentrations produced during different dental procedures under different mitigation processes. METHOD Aerosol concentrations were measured by the Optical Particle Sensor (OPS) and Wideband Integrated Bioaerosol Sensor (WIBS) during routine, time-recorded dental procedures on a manikin head in a partitioned enclosure. Four different, standardised dental procedures were repeated in triplicate for three different mitigation measures. RESULT Both high-volume evacuation (HVE) and HVE plus extra-oral suction (LEV) eradicated all procedure-related aerosols, and the enclosure stopped procedure-related aerosols escaping. Aerosols recorded by the OPS and WIBS were 84 and 16-fold higher than background levels during tooth 16 FDI notation (UR6) drilling, and 11 and 24-fold higher during tooth 46 FDI notation (LR6) drilling, respectively. Ultrasonic scaling around the full lower arch (CL) or the full upper arch (CU) did not generate detectable aerosols with mitigation applied. Without mitigation the largest concentration of inhalable particles during procedures observed by the WIBS and OPS was during LR6 (139/cm3) and UR6 (28/cm3) drilling, respectively. Brief aerosol bursts were recorded during drilling procedures with HVE, these did not occur with LEV, suggesting LEV provides protection against operator errors. Variation was observed in necessary fallow times (49 - 280 minutes) without mitigation, while no particles remained airborne when mitigation was utilised. CONCLUSION This data demonstrates that correctly positioned HVE or LEV is effective in preventing airborne spread and persistence of inhalable particles originating from dental AGPs. Additionally, a simple enclosure restricts the spread of aerosols outside of the operating area. CLINICAL SIGNIFICANCE Employing correctly positioned HVE and LEV in non-mechanically ventilated clinics can prevent the dispersal and persistence of inhalable airborne particles during dental AGPs. Moreover, using enclosures have the additive effect of restricting aerosol spread outside of an operating area.
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Affiliation(s)
- Mehael Fennelly
- School of Chemistry and Environmental Research Institute, University College Cork; Department of Pathology, University College Cork.
| | | | - Mairead Harding
- University Dental School & Hospital, University College Cork; Oral Health Services Research Centre, University College Cork
| | - Stig Hellebust
- School of Chemistry and Environmental Research Institute, University College Cork
| | - John Wenger
- School of Chemistry and Environmental Research Institute, University College Cork
| | - Niall O'Sullivan
- School of Chemistry and Environmental Research Institute, University College Cork
| | | | - Michael Prentice
- Department of Pathology, University College Cork; APC Microbiome Institute, University College Cork
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18
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Chen K, Wu J, Yarin A. Electrospun membranes filtering 100 nm particles from air flow by means of the van der Waals and Coulomb forces. J Memb Sci 2022; 644:120138. [PMID: 36567692 PMCID: PMC9759630 DOI: 10.1016/j.memsci.2021.120138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/14/2021] [Accepted: 11/24/2021] [Indexed: 12/27/2022]
Abstract
Nonwoven fibrous filter membranes are widely used in filtration because of their low cost. They are less effective in intercepting airborne particles of the order of 100 nm, which is of the SARS-CoV-2 (COVID-19) virus's size. Many diseases, including COVID-19, predominantly spread by droplets released by breathing, coughing, sneezing, or medical procedures. It was shown that the smallest droplets can evaporate in air before settling, thus, making viruses airborne and easily penetrating even the best masks and filters. As a result, air-filtering membranes, which are capable of effective interception of ∼100 nm nanoparticles are highly desirable. A traditional way to improve filtration efficiency by overlapping several layers of nonwoven fabrics increases the required pressure drop, and thus, should be avoided as much as possible. Here, we propose and demonstrate an innovative approach to enhance performance of filtration membranes based on (i) a dramatic reduction in the fiber size, and (ii) metal coating of the fibers. The first component of this approach allows one to incorporate a novel physical mechanism of filtration, the short-range van der Waals forces, whereas the second one adds the long-range electric Coulomb forces if the oncoming nanoparticles are pre-charged and the metal-plated membrane grounded. In the present work, the ∼100 nm aluminum nanoparticles are filtered as a model of commensurate airborne single COVID-19 viruses, and Platinum is used as the sputter-coated material for the fiber coating. The resulting filtration efficiency enhanced by the electric Coulomb forces alone is increased by the factor of 1.77, while the filtration efficiency additionally facilitated by the van der Waals forces increased by the factor of 2.44. In comparison to the filter membranes with ∼500 nm fibers without the electric forces involved, the van-der-Waals-electric filter membrane with fibers ∼90 nm is 2.24 × 1.77 = 3.96 times more effective. The quality factor of a membrane which combines the van der Waals and Coulomb forces is 10.6 psi-1, which is almost three times that of a comparable membrane without the electric Coulomb force (with only van der Waals forces being used).
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Affiliation(s)
- Kailin Chen
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street, Chicago, IL, 60607-7022, USA
| | - Jingwei Wu
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street, Chicago, IL, 60607-7022, USA
| | - A.L. Yarin
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, 842 W. Taylor Street, Chicago, IL, 60607-7022, USA,School of Mechanical Engineering, Korea University, Seoul 136-713, Republic of Korea,Corresponding author. School of Mechanical Engineering, Korea University, Seoul 136-713, Republic of Korea
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19
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Biswas R, Pal A, Pal R, Sarkar S, Mukhopadhyay A. Risk assessment of COVID infection by respiratory droplets from cough for various ventilation scenarios inside an elevator: An OpenFOAM-based computational fluid dynamics analysis. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2022; 34:013318. [PMID: 35340680 PMCID: PMC8939552 DOI: 10.1063/5.0073694] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 12/30/2021] [Indexed: 05/15/2023]
Abstract
Respiratory droplets-which may contain disease spreading virus-exhaled during speaking, coughing, or sneezing are one of the significant causes for the spread of the ongoing COVID-19 pandemic. The droplet dispersion depends on the surrounding air velocity, ambient temperature, and relative humidity. In a confined space like an elevator, the risk of transmission becomes higher when there is an infected person inside the elevator with other individuals. In this work, a numerical investigation is carried out in a three-dimensional domain resembling an elevator using OpenFoam. Three different modes of air ventilation, viz., quiescent, axial exhaust draft, and exhaust fan, have been considered to investigate the effect of ventilation on droplet transmission for two different climatic conditions (30 °C , 50% relative humidity and 10 °C , 90% relative humidity). The risk assessment is quantified using a risk factor based on the time-averaged droplet count present near the passenger's hand to head region (risky height zone). The risk factor drops from 40% in a quiescent scenario to 0% in an exhaust fan ventilation condition in a hot dry environment. In general, cold humid conditions are safer than hot dry conditions as the droplets settle down quickly below the risky height zone owing to their larger masses maintained by negligible evaporation. However, an exhaust fan renders the domain in a hot dry ambience completely safe (risk factor, 0%) in 5.5 s whereas it takes 7.48 s for a cold humid ambience.
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Affiliation(s)
- Riddhideep Biswas
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
| | - Anish Pal
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
| | - Ritam Pal
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Sourav Sarkar
- Department of Mechanical Engineering, Jadavpur University, Kolkata-700032, India
- Author to whom correspondence should be addressed:
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20
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Wang H, Li Z, Liu Y, Zhu L, Zhou Z. Experimental study of the dispersion of cough-generated droplets from a person going up- or downstairs. AIP ADVANCES 2022; 12:015002. [PMID: 35003882 PMCID: PMC8734944 DOI: 10.1063/5.0073880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/22/2021] [Indexed: 06/14/2023]
Abstract
The dispersion of cough-generated droplets from a person going up- or downstairs was investigated through a laboratory experiment in a water tunnel. This experiment was carried out with a manikin mounted at inclination angles facing the incoming flow to mimic a person going up or down. Detailed velocity measurements and flow visualization were conducted in the water tunnel experiments. To investigate the influence of the initial position on the motion of particles, a virtual particle approach was adopted to simulate the dispersion of particles using the measured velocity field. Particle clustering, which is caused by the unsteadiness of the flow, was observed in both flow visualization and virtual particle simulation. For the case of going upstairs, particles are concentrated below the person's shoulder and move downward with a short travel distance. For the case of going downstairs, particles dispersing over the person's head advect over for a long distance. We also found that the motion of the particles is closely related to the initial position. According to the results in this study, suggestions for the prevention of respiratory infectious disease are made.
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21
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Shrestha P, DeGraw JW, Zhang M, Liu X. Multizonal modeling of SARS-CoV-2 aerosol dispersion in a virtual office building. BUILDING AND ENVIRONMENT 2021; 206:108347. [PMID: 34566243 PMCID: PMC8451446 DOI: 10.1016/j.buildenv.2021.108347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/28/2021] [Accepted: 09/12/2021] [Indexed: 05/25/2023]
Abstract
The dispersion of indoor airborne contaminants across different zones within a mechanically ventilated building is a complex phenomenon driven by multiple factors. In this study, we modeled the indoor dispersion of airborne SARS-CoV-2 aerosols within a US Department of Energy detailed medium office prototype building using CONTAM software. The aim of this study is to improve our understanding about how different parts of a building can experience varying concentrations of the airborne viruses under different circumstances of release and mitigation strategies. Results indicate that unventilated stairwells can have significantly higher concentrations of airborne viruses. The mitigation strategies of morning and evening flushing of conditioned zones were not found to be very effective. Instead, a constant high percentage of outdoor air in the supply mix, and the use of masks, portable HEPA air cleaners, MERV 13 or higher HVAC air filters, and ultraviolet germicidal irradiation disinfection were effective strategies to prevent airborne viral contamination in the majority of the simulated office building.
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Affiliation(s)
- Prateek Shrestha
- Integrated Building Performance Group, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Jason W DeGraw
- Integrated Building Performance Group, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Mingkan Zhang
- Multifunctional Equipment Integration Group, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Xiaobing Liu
- Building Equipment Research Group, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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22
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Peña-Monferrer C, Antao S, Manson-Sawko R. Numerical investigation of droplets in a cross-ventilated space with sitting passengers under asymptomatic virus transmission conditions. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:123314. [PMID: 35002204 PMCID: PMC8728630 DOI: 10.1063/5.0070625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 11/05/2021] [Indexed: 06/14/2023]
Abstract
Asymptomatic virus transmission in public transportation is a complex process that is difficult to analyze computationally and experimentally. We present a high-resolution computational study for investigating droplet dynamics under a speech-like exhalation mode. A large eddy simulation coupled with Lagrangian tracking of drops was used to model a rectangular space with sitting thermal bodies and cross-ventilated with a multislot diffuser. Release of drops from different seat positions was evaluated to analyze the decontamination performance of the ventilation system. The results showed an overall good performance, with an average of 24.1% of droplets removed through the exhaust in the first 40 s. The droplets' distribution revealed that higher concentrations were less prevalent along the center of the domain where the passengers sit. Longitudinal contamination between rows was noted, which is a negative aspect for containing the risk of infection in a given row but has the benefit of diluting the concentration of infectious droplets. Droplets from the window seat raised more vertically and invaded the space of other passengers to a lesser extent. In contrast, droplets released from the middle seat contaminated more the aisle passenger's space, indicating that downward flow from personal ventilation could move down droplets to its breathing region. Droplets released from the aisle were dragged down by the ventilation system immediately. The distance of drops to the mouth of the passengers showed that the majority passed at a relatively safe distance. However, a few of them passed at a close distance of the order of magnitude of 1 cm.
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Affiliation(s)
- C Peña-Monferrer
- IBM Research Europe, The Hartree Centre, Warrington WA4 4AD, United Kingdom
| | - S Antao
- IBM Research Europe, The Hartree Centre, Warrington WA4 4AD, United Kingdom
| | - R Manson-Sawko
- IBM Research Europe, The Hartree Centre, Warrington WA4 4AD, United Kingdom
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Sinha K, Yadav MS, Verma U, Murallidharan JS, Kumar V. Effect of recirculation zones on the ventilation of a public washroom. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:117101. [PMID: 34803365 PMCID: PMC8597714 DOI: 10.1063/5.0064337] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 09/19/2021] [Indexed: 05/29/2023]
Abstract
Air-borne transmission can pose a major risk of infection spread in enclosed spaces. Venting the air out using exhaust fans and ducts is a common approach to mitigate the risk. In this work, we study the air flow set up by an exhaust fan in a typical shared washroom that can be a potential hot spot for COVID-19 transmission. The primary focus is on the regions of recirculating flow that can harbor infectious aerosol for much longer than the well-ventilated parts of the room. Computational fluid dynamics is used to obtain the steady state air flow field, and Lagrangian tracking of particles gives the spatial and temporal distribution of infectious aerosol in the domain. It is found that the washbasin located next to the door is in a prominent recirculation zone, and particles injected in this region take much longer to be evacuated. The ventilation rate is found to be governed by the air residence time in the recirculation zone, and it is much higher than the timescale based on fully mixed reactor model of the room. Increasing the fan flow rate can reduce the ventilation time, but cannot eliminate the recirculation zones in the washroom.
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Affiliation(s)
| | | | - Utkarsh Verma
- Indian Institute of Technology Bombay, Mumbai, India
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24
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Li X, Mak CM, Wai Ma K, Wong HM. How the high-volume evacuation alters the flow-field and particle removal characteristics in the mock-up dental clinic. BUILDING AND ENVIRONMENT 2021; 205:108225. [PMID: 34376905 PMCID: PMC8343392 DOI: 10.1016/j.buildenv.2021.108225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/17/2021] [Accepted: 08/02/2021] [Indexed: 05/09/2023]
Abstract
The exposure risk of droplets and aerosols emitted from the oral cavity to the dental professionals and patients has received more attention especially the ongoing outbreak of COVID-19. The aim of this study is to address the question about how the use of the high-volume evacuation (HVE) alters the risk profiles compared with the situation only personal protective equipment (PPE). The risk profiles of the different situations were analyzed in terms of droplet velocity, flow field characteristics, and particle removal efficiency. The ultrasonic scaling with suction was performed in the mock-up experimental dental clinic, and the instantaneous moment when the HVE acted on the droplets was visualized using a laser light scattering technique. From the results of the velocity profiles, the hypothesis about the moderate effect of the HVE on high-velocity small droplets near the mannequin's mouth had been firstly proven in this study. The suction can be characterized as low-threshold equipment to bring substantial benefits to reduce the area of the contaminated region. Once the cooperation of suction, the pair of vortexes that were in the face shield area of the dental professional would be eliminated, removing the high-level contaminated region near the breathing area of dental professionals. Compared with the low and medium volume evacuation, the particle removal efficiency of the HVE was more stable at 60%. The research will provide references to the HVE recommendation in the dentistry clinical practice guidelines.
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Affiliation(s)
- Xiujie Li
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Cheuk Ming Mak
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Kuen Wai Ma
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Hai Ming Wong
- Faculty of Dentistry, The University of Hong Kong, Pok Fu Lam, Hong Kong Island, Hong Kong
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25
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Pourfattah F, Wang LP, Deng W, Ma YF, Hu L, Yang B. Challenges in simulating and modeling the airborne virus transmission: A state-of-the-art review. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:101302. [PMID: 34803360 PMCID: PMC8597718 DOI: 10.1063/5.0061469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 10/04/2021] [Indexed: 06/09/2023]
Abstract
Recently, the COVID-19 virus pandemic has led to many studies on the airborne transmission of expiratory droplets. While limited experiments and on-site measurements offer qualitative indication of potential virus spread rates and the level of transmission risk, the quantitative understanding and mechanistic insights also indispensably come from careful theoretical modeling and numerical simulation efforts around which a surge of research papers has emerged. However, due to the highly interdisciplinary nature of the topic, numerical simulations of the airborne spread of expiratory droplets face serious challenges. It is essential to examine the assumptions and simplifications made in the existing modeling and simulations, which will be reviewed carefully here to better advance the fidelity of numerical results when compared to the reality. So far, existing review papers have focused on discussing the simulation results without questioning or comparing the model assumptions. This review paper focuses instead on the details of the model simplifications used in the numerical methods and how to properly incorporate important processes associated with respiratory droplet transmission. Specifically, the critical issues reviewed here include modeling of the respiratory droplet evaporation, droplet size distribution, and time-dependent velocity profile of air exhaled from coughing and sneezing. According to the literature review, another problem in numerical simulations is that the virus decay rate and suspended viable viral dose are often not incorporated; therefore here, empirical relationships for the bioactivity of coronavirus are presented. It is hoped that this paper can assist researchers to significantly improve their model fidelity when simulating respiratory droplet transmission.
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Affiliation(s)
- Farzad Pourfattah
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | | | - Weiwei Deng
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Yong-Feng Ma
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Liangquan Hu
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Bo Yang
- Guangdong Provincial Key Laboratory of Turbulence Research and Applications, Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
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26
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Haffner EA, Bagheri M, Higham JE, Cooper L, Rowan S, Stanford C, Mashayek F, Mirbod P. An experimental approach to analyze aerosol and splatter formations due to a dental procedure. EXPERIMENTS IN FLUIDS 2021; 62:202. [PMID: 34566249 PMCID: PMC8449526 DOI: 10.1007/s00348-021-03289-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/20/2021] [Accepted: 08/22/2021] [Indexed: 05/16/2023]
Abstract
Throughout 2020 and beyond, the entire world has observed a continuous increase in the infectious spread of the novel coronavirus (SARS-CoV-2) otherwise known as COVID-19. The high transmission of this airborne virus has raised countless concerns regarding safety measures employed in the working conditions for medical professionals. Specifically, those who perform treatment procedures on patients which intrinsically create mists of fine airborne droplets, i.e., perfect vectors for this and other viruses to spread. The present study focuses on understanding the splatter produced due to a common dentistry technique to remove plaque buildup on teeth. This technique uses a high-speed dentistry instrument, e.g., a Cavitron ultrasonic scaler, to scrape along the surface of a patient's teeth. This detailed understanding of the velocity and the trajectory of the droplets generated by the splatter will aid in the development of hygiene mechanisms to guarantee the safety of those performing these procedures and people in clinics or hospitals. Optical flow tracking velocimetry (OFTV) method was employed to obtain droplet velocity and trajectory in a two-dimensional plane. Multiple data collection planes were taken in different orientations around a model of adult mandibular teeth. This technique provided pseudo-three-dimensional velocity information for the droplets within the splatter developed from this high-speed dental instrument. These results indicated that within the three-dimensional splatter produced there were high velocities (1-2 m/s) observed directly below the intersection point between the front teeth and the scaler. The splatter formed a cone-shape structure that propagated 10-15 mm away from the location of the scaler tip. From the droplet trajectories, it was observed that high velocity isolated droplets propagate away from the bulk of the splatter. It is these droplets which are concerning for health safety to those performing the medical procedures. Using a shadowgraphy technique, we further characterize the individual droplets' size and their individual velocity. We then compare these results to previously published distributions. The obtained data can be used as a first step to further examine flow and transport of droplets in clinics/dental offices.
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Affiliation(s)
- E. A. Haffner
- Department of Mechanical and Industrial Engineering, University of Illinois At Chicago, Chicago, IL USA
| | - M. Bagheri
- Department of Mechanical and Industrial Engineering, University of Illinois At Chicago, Chicago, IL USA
| | - J. E. Higham
- School of Environmental Sciences, University of Liverpool, Liverpool, UK
| | - L. Cooper
- College of Dentistry, University of Illinois At Chicago, Chicago, IL USA
| | - S. Rowan
- College of Dentistry, University of Illinois At Chicago, Chicago, IL USA
| | - C. Stanford
- College of Dentistry, University of Illinois At Chicago, Chicago, IL USA
| | - F. Mashayek
- Department of Mechanical and Industrial Engineering, University of Illinois At Chicago, Chicago, IL USA
| | - P. Mirbod
- Department of Mechanical and Industrial Engineering, University of Illinois At Chicago, Chicago, IL USA
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27
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Vadivukkarasan M. A note on the stability characteristics of the respiratory events. EUROPEAN JOURNAL OF MECHANICS. B, FLUIDS 2021; 89:15-20. [PMID: 33994752 PMCID: PMC8107050 DOI: 10.1016/j.euromechflu.2021.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 05/03/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
The present outbreak enables the researchers from fluid mechanics to widen the understanding of expelling respiratory liquids from a unique perspective to diminish the persistence of COVID-19. This article focuses on uncovering the instability mechanism responsible for forming droplets and aerosols during respiratory events such as breathing, talking, coughing and sneezing. We illustrate a mathematical framework by revisiting the model (Vadivukkarasan and Panchagnula, 2017) and show the associated instabilities during respiratory events. We envisage the combined Rayleigh-Taylor-Kelvin-Helmholtz (R-T-K-H) model as a robust tool for respiratory events. This study highlights the distinct possibility of respiratory droplet formation over multiple instabilities and provides a fundamental understanding. We present the different dominant modes through a ternary phase diagram for three-dimensional numbers (Bond number and Weber numbers). Furthermore, this model can be extended phenomenologically to viscous fluids to satisfy mucus and saliva in the respiratory liquids.
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Affiliation(s)
- M Vadivukkarasan
- Department of Mechanical Engineering, National Institute of Technology Puducherry, Karaikal, 609609, India
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28
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Roy T, Damoulakis G, Komperda J, Mashayek F, Cooper LF, Rowan SA, Megaridis CM. Effect of H 2O 2 Antiseptic on Dispersal of Cavitation-Induced Microdroplets. J Dent Res 2021; 100:1258-1264. [PMID: 34334033 DOI: 10.1177/00220345211027550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The persisting outbreak of SARS-CoV-2 has posed an enormous threat to global health. The sustained human-to-human transmission of SARS-CoV-2 via respiratory droplets makes the medical procedures around the perioral area vulnerable to the spread of the disease. Such procedures include the ultrasonic dental cleaning method, which occurs within the oral cavity and involves cavitation-induced sprays, thus increasing the risk of pathogen transmission via advection. To understand the associated health and safety risks for patients and clinicians, it is critical to understand the flow pattern of the spray cloud around the operating region, the size and velocity distribution of the emitted droplets, and the extent of fluid dispersion until ultimate deposit on surfaces or escape through air vents. In this work, the droplet size and velocity distributions of the spray emerging from the tip of a free-standing common ultrasonic dental cleaning device were characterized via high-speed imaging. Deionized water and 1.5% and 3% aqueous hydrogen peroxide (H2O2) solutions were used as working fluids, with the H2O2-an established oxidizing agent-intended to curb the survival of virus released in aerosols generated from dental procedures. The measurements reveal that the presence of H2O2 in the working fluid increases the mean droplet size and ejection velocity. Detailed computational fluid dynamic simulations with multiphase flow models reveal benefits of adding small amounts of H2O2 in the feed stream of the ultrasonic cleaner; this practice causes larger droplets with shorter residence times inside the clinic before settling down or escaping through air vents. The results suggest optimal benefits (in terms of fluid spread) of adding 1.5% H2O2 in the feed stream during dental procedures involving ultrasonic tools. The present findings are not specific to the COVID-19 pandemic but should also apply to future outbreaks caused by airborne droplet transmission.
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Affiliation(s)
- T Roy
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, USA
| | - G Damoulakis
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, USA
| | - J Komperda
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, USA
| | - F Mashayek
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, USA
| | - L F Cooper
- College of Dentistry, University of Illinois at Chicago, Chicago, IL, USA
| | - S A Rowan
- College of Dentistry, University of Illinois at Chicago, Chicago, IL, USA
| | - C M Megaridis
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL, USA
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29
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Peña-Monferrer C, Antao S, Manson-Sawko R. Numerical investigation of respiratory drops dynamics released during vocalization. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:083321. [PMID: 34471339 PMCID: PMC8404381 DOI: 10.1063/5.0059419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/01/2021] [Indexed: 05/14/2023]
Abstract
Release of drops from a human body has been the focus of many recent investigations because of the current COVID-19 pandemic. Indirect virus transmission from asymptomatic individuals has been proved to be one of the major infectious routes and difficult to quantify, detect, and mitigate. We show in this work a detailed and novel numerical investigation of drops released during vocalization from a thermal manikin using a large eddy simulation coupled with Lagrangian tracking of drops. The vocalization experiment was modeled using existing data from the literature for modeling exhaled airflow, emission rate, and size distribution. Particular focus was on the definition of the boundary conditions for the exhalation process. Turbulence was compared with experimental data for the near mouth region for 75 exhalation breathing cycles and showed the sensitivity of different modeling assumptions at the mouth inlet. The results provide insights of special interest for understanding drop dynamics in speech-like exhalation modes, modeling the mouth inlet boundary conditions, and providing data for verifying other more simplified models.
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Affiliation(s)
- C. Peña-Monferrer
- IBM Research Europe, The Hartree Centre, Warrington WA4 4Ad, United Kingdom
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30
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Esteban Florez FL, Thibodeau T, Oni T, Floyd E, Khajotia SS, Cai C. Size-resolved spatial distribution analysis of aerosols with or without the utilization of a novel aerosol containment device in dental settings. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:085102. [PMID: 34471340 PMCID: PMC8404378 DOI: 10.1063/5.0056229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/10/2021] [Indexed: 05/06/2023]
Abstract
The coronavirus disease 2019 pandemic has imposed unprecedented occupational challenges for healthcare professionals. In dentistry, handheld instruments such as air and electric handpieces, ultrasonic scalers, and air/water syringes are capable of generating aerosols, droplets, and splatter, thereby exposing dental professionals to airborne contaminants such as viruses, bacteria, and fungi. The objective of the present study was to determine the spatial distribution of aerosols by size (0.30 to 20.00 μm) and the efficacy of a novel aerosol containment device (ACD) in a large operatory room with 12 dental chairs. Real-time portable laser aerosol spectrometers were used to measure the size-resolved number concentration of aerosols generated by a collision nebulizer. Results reported demonstrate that aerosol number concentrations significantly decreased as a function of distance with or without the utilization of the ACD. The ACD was able to efficiently decrease (up to 8.56-fold) the number and size distribution of particles in a large dental clinic. The novel device demonstrated higher efficiency for particles shown to contain the highest levels of severe acute respiratory syndrome coronavirus 2 in Chinese hospitals, thereby showing great promise to potentially decrease the spreading of nosocomial pathogens in dental settings.
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Affiliation(s)
- Fernando Luis Esteban Florez
- Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, The University of Oklahoma Health Sciences Center, 1201 N. Stonewall Avenue, Oklahoma City, Oklahoma 73117, USA
| | - Tyler Thibodeau
- School of Industrial and Systems Engineering, The University of Oklahoma, 202 W. Boyd Street, Norman, Oklahoma 73019, USA
| | - Toluwanimi Oni
- Department of Occupational and Environmental Health, Hudson College of Public Health, The University of Oklahoma Health Sciences Center, 801 N.E. 13th Street, Oklahoma City, Oklahoma 73126, USA
| | - Evan Floyd
- Department of Occupational and Environmental Health, Hudson College of Public Health, The University of Oklahoma Health Sciences Center, 801 N.E. 13th Street, Oklahoma City, Oklahoma 73126, USA
| | - Sharukh S. Khajotia
- Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, The University of Oklahoma Health Sciences Center, 1201 N. Stonewall Avenue, Oklahoma City, Oklahoma 73117, USA
| | - Changjie Cai
- Department of Occupational and Environmental Health, Hudson College of Public Health, The University of Oklahoma Health Sciences Center, 801 N.E. 13th Street, Oklahoma City, Oklahoma 73126, USA
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31
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Ooi CC, Suwardi A, Ou Yang ZL, Xu G, Tan CKI, Daniel D, Li H, Ge Z, Leong FY, Marimuthu K, Ng OT, Lim SB, Lim P, Mak WS, Cheong WCD, Loh XJ, Kang CW, Lim KH. Risk assessment of airborne COVID-19 exposure in social settings. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:087118. [PMID: 34552314 PMCID: PMC8450907 DOI: 10.1063/5.0055547] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 08/09/2021] [Indexed: 05/04/2023]
Abstract
The COVID-19 pandemic has led to many countries oscillating between various states of lock-down as they seek to balance keeping the economy and essential services running and minimizing the risk of further transmission. Decisions are made about which activities to keep open across a range of social settings and venues guided only by ad hoc heuristics regarding social distancing and personal hygiene. Hence, we propose the dual use of computational fluid dynamic simulations and surrogate aerosol measurements for location-specific assessment of risk of infection across different real-world settings. We propose a 3-tiered risk assessment scheme to facilitate classification of scenarios into risk levels based on simulations and experiments. Threshold values of <54 and >840 viral copies and <5% and >40% of original aerosol concentration are chosen to stratify low, medium, and high risk. This can help prioritize allowable activities and guide implementation of phased lockdowns or re-opening. Using a public bus in Singapore as a case study, we evaluate the relative risk of infection across scenarios such as different activities and passenger positions and demonstrate the effectiveness of our risk assessment methodology as a simple and easily interpretable framework. For example, this study revealed that the bus's air-conditioning greatly influences dispersion and increases the risk of certain seats and that talking can result in similar relative risk to coughing for passengers around an infected person. Both numerical and experimental approaches show similar relative risk levels with a Spearman's correlation coefficient of 0.74 despite differing observables, demonstrating applicability of this risk assessment methodology to other scenarios.
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Affiliation(s)
- Chin Chun Ooi
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
| | - Ady Suwardi
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore 138634
| | - Zhong Liang Ou Yang
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
| | - George Xu
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
| | - Chee Kiang Ivan Tan
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore 138634
| | - Dan Daniel
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore 138634
| | - Hongying Li
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
| | - Zhengwei Ge
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
| | - Fong Yew Leong
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
| | - Kalisvar Marimuthu
- National Centre for Infectious Diseases, Tan Tock Seng Hospital, 16 Jalan Tan Tock Seng, Singapore 308443
| | - Oon Tek Ng
- National Centre for Infectious Diseases, Tan Tock Seng Hospital, 16 Jalan Tan Tock Seng, Singapore 308443
| | - Shin Bin Lim
- Ministry of Health Singapore, College of Medicine Building, 16 College Road, Singapore 169854
| | - Peter Lim
- Land Transport Authority, 1 Hampshire Road, Singapore 219428
| | - Wai Siong Mak
- Land Transport Authority, 1 Hampshire Road, Singapore 219428
| | - Wun Chet Davy Cheong
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore 138634
| | - Xian Jun Loh
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore 138634
| | - Chang Wei Kang
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
| | - Keng Hui Lim
- Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632
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32
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Arumuru V, Samantaray SS, Pasa J. Double masking protection vs. comfort-A quantitative assessment. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:077120. [PMID: 34335010 PMCID: PMC8320463 DOI: 10.1063/5.0058571] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/05/2021] [Indexed: 05/02/2023]
Abstract
COVID-19 has forced humankind to adopt face masks as an integral part of everyday life. This preventive measure is an effective source control technique to curb the spread of COVID-19 and other similar diseases. The virus responsible for causing COVID-19 has undergone several mutations in the recent past, including B.1.1.7, B.1.351, P.1, and N501Y, B.1.617, with a higher infectious rate. These viruses' variants are mainly responsible for the recent spike in COVID-19 cases and associated steep rise in mortality rate worldwide. Under these circumstances, the Center for Disease Control (CDC) and health experts recommend double masking, which mainly includes a surgical mask and a cotton mask for the general public. This combination provides an additional layer of protection and masks fitment to minimize the leakage of droplets expelled during coughing, sneezing, talking, and breathing. This leakage may cause airborne transmission of the virus. In the present study, we report a systematic quantitative unsteady pressure measurement supplement with flow visualization to quantify the effectiveness of a single and double mask. We have also evaluated double masking consisting of a surgical mask and an N-95 mask used by medical professionals. A simple knot improves the surgical mask fitment significantly, and hence, the leakage of droplets is minimized. The leakage of the droplets was reduced to a large extent by using a double mask combination of a two-layer cotton mask over the surgical mask with a knot. The double mask combination of surgical + N-95 and two-layer cotton + N-95 masks showed the most promising results, and no leakage of the droplets is observed in the forward direction. A double mask combination of surgical and N-95 mask offers 8.6% and 5.6% lower mean and peak pressures compared to surgical, and cotton mask. The best results are observed with cotton and N-95 masks with 54.6% and 23% lower mean and peak pressures than surgical and cotton masks; hence, this combination will offer more comfort to the wearer.
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Affiliation(s)
- Venugopal Arumuru
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 752050, India
| | - Sidhartha Sankar Samantaray
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 752050, India
| | - Jangyadatta Pasa
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 752050, India
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33
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Winter J, Frankenberger R, Günther F, Roggendorf MJ. Dental Education during the COVID-19 Pandemic in a German Dental Hospital. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:6905. [PMID: 34199085 PMCID: PMC8297123 DOI: 10.3390/ijerph18136905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 06/20/2021] [Accepted: 06/24/2021] [Indexed: 11/30/2022]
Abstract
Due to the SARS-CoV-2 pandemic, dental treatment performed by undergraduate students at the University of Marburg/Germany was immediately stopped in spring 2020 and stepwise reinstalled under a new hygiene concept until full recovery in winter 2020/21. Patient treatment in the student courses was evaluated based on three aspects: (1) Testing of patients with a SARS-CoV-2 Rapid Antigen (SCRA) Test applied by student assistants (SA); (2) Improved hygiene regimen, with separated treatment units, cross-ventilation, pre-operative mouth rinse and rubber dam application wherever possible; (3) Recruitment of patients: 735 patients were pre-registered for the two courses; 384 patients were treated and a total of 699 tests with the SCRA test were performed by SAs. While half of the patients treated in the course were healthy, over 40% of the patients that were pre-registered but not treated in the course revealed a disease being relevant to COVID (p < 0.001). 46 patients had concerns to visit the dental hospital due to the increase of COVID incidence levels, 14 persons refused to be tested. The presented concept was suitable to enable patient treatment in the student course during the SARS-CoV-2 pandemic.
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Affiliation(s)
- Julia Winter
- Department of Operative Dentistry, Endodontics, and Pediatric Dentistry, Medical Center for Dentistry, Philipps University Marburg and University Medical Center Giessen and Marburg (Campus Marburg), Georg Voigt Str. 3, 35039 Marburg, Germany; (J.W.); (R.F.)
| | - Roland Frankenberger
- Department of Operative Dentistry, Endodontics, and Pediatric Dentistry, Medical Center for Dentistry, Philipps University Marburg and University Medical Center Giessen and Marburg (Campus Marburg), Georg Voigt Str. 3, 35039 Marburg, Germany; (J.W.); (R.F.)
| | - Frank Günther
- Institute for Medical Microbiology and Hygiene, Marburg University Hospital, Hans-Meerwein-Straße 2, 35043 Marburg, Germany;
| | - Matthias Johannes Roggendorf
- Department of Operative Dentistry, Endodontics, and Pediatric Dentistry, Medical Center for Dentistry, Philipps University Marburg and University Medical Center Giessen and Marburg (Campus Marburg), Georg Voigt Str. 3, 35039 Marburg, Germany; (J.W.); (R.F.)
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34
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Mirikar D, Palanivel S, Arumuru V. Droplet fate, efficacy of face mask, and transmission of virus-laden droplets inside a conference room. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:065108. [PMID: 34248325 PMCID: PMC8232678 DOI: 10.1063/5.0054110] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/13/2021] [Indexed: 05/16/2023]
Abstract
The second and third waves of coronavirus disease-2019 (COVID-19) pandemic have hit the world. Even after more than a year, the economy is yet to return to a semblance of normality. The conference/meeting room is one of the critical sections of offices that might be difficult not to use. This study analyzes the distribution of the virus-laden droplets expelled by coughing inside a conference room, the effect of ventilation rates, and their positioning. The efficacy of masks is studied to get quantitative information regarding the residence time of the droplets. The effects of evaporation, turbulent dispersion, and external forces have been considered for calculating the droplets' trajectories. We have analyzed six cases, of which two are with masks. Change in the ventilation rate from four air changes per hour (ACH) to eight resulted in a 9 % increment in the number of droplets entrained in the outlet vent, while their average residence time was reduced by ∼ 8 s . The shift in the vents' location has significantly altered droplets' distribution inside a conference room. It results in ∼ 1.5 % of the injected droplets reaching persons sitting across the table, and a similar indoor environment is not recommended. Wearing a mask in the case of eight ACH has presented the best scenario out of the six cases, with a 6.5 % improvement in the number of droplets entrained in the outlet vent and a 9 s decrease in their average residence time compared to the case without a mask. No droplets have reached persons sitting across the table when the infected person is wearing the mask, which follows that a social distancing of 6 ft with a mask is adequate in indoor environments.
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Affiliation(s)
- Dnyanesh Mirikar
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 752050, India
| | - Silambarasan Palanivel
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 752050, India
| | - Venugopal Arumuru
- Applied Fluids Group, School of Mechanical Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 752050, India
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