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Bain A, Ghosh K, Prisle NL, Bzdek BR. Surface-Area-to-Volume Ratio Determines Surface Tensions in Microscopic, Surfactant-Containing Droplets. ACS Cent Sci 2023; 9:2076-2083. [PMID: 38033804 PMCID: PMC10683496 DOI: 10.1021/acscentsci.3c00998] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 12/02/2023]
Abstract
The surface composition of aerosol droplets is central to predicting cloud droplet number concentrations, understanding atmospheric pollutant transformation, and interpreting observations of accelerated droplet chemistry. Due to the large surface-area-to-volume ratios of aerosol droplets, adsorption of surfactant at the air-liquid interface can deplete the droplet's bulk concentration, leading to droplet surface compositions that do not match those of the solutions that produced them. Through direct measurements of individual surfactant-containing, micrometer-sized droplet surface tensions, and fully independent predictive thermodynamic modeling of droplet surface tension, we demonstrate that, for strong surfactants, the droplet's surface-area-to-volume ratio becomes the key factor in determining droplet surface tension rather than differences in surfactant properties. For the same total surfactant concentration, the surface tension of a droplet can be >40 mN/m higher than that of the macroscopic solution that produced it. These observations indicate that an explicit consideration of surface-area-to-volume ratios is required when investigating heterogeneous chemical reactivity at the surface of aerosol droplets or estimating aerosol activation to cloud droplets.
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Affiliation(s)
- Alison Bain
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Kunal Ghosh
- Center
for Atmospheric Research, University of
Oulu, Oulu 90014, Finland
| | - Nønne L. Prisle
- Center
for Atmospheric Research, University of
Oulu, Oulu 90014, Finland
| | - Bryan R. Bzdek
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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2
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Hamilton V, Sheikh S, Szczepanska A, Maskell N, Hamilton F, Reid JP, Bzdek BR, Murray JRD. Diathermy and bone sawing are high aerosol yield procedures. Bone Joint Res 2023; 12:636-643. [PMID: 37813391 PMCID: PMC10562079 DOI: 10.1302/2046-3758.1210.bjr-2023-0028.r1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/11/2023] Open
Abstract
Aims Orthopaedic surgery uses many varied instruments with high-speed, high-impact, thermal energy and sometimes heavy instruments, all of which potentially result in aerosolization of contaminated blood, tissue, and bone, raising concerns for clinicians' health. This study quantifies the aerosol exposure by measuring the number and size distribution of the particles reaching the lead surgeon during key orthopaedic operations. Methods The aerosol yield from 17 orthopaedic open surgeries (on the knee, hip, and shoulder) was recorded at the position of the lead surgeon using an Aerodynamic Particle Sizer (APS; 0.5 to 20 μm diameter particles) sampling at 1 s time resolution. Through timestamping, detected aerosol was attributed to specific procedures. Results Diathermy (electrocautery) and oscillating bone saw use had a high aerosol yield (> 100 particles detected per s) consistent with high exposure to aerosol in the respirable range (< 5 µm) for the lead surgeon. Pulsed lavage, reaming, osteotome use, and jig application/removal were medium aerosol yield (10 to 100 particles s-1). However, pulsed lavage aerosol was largely attributed to the saline jet, osteotome use was always brief, and jig application/removal had a large variability in the associated aerosol yield. Suctioning (with/without saline irrigation) had a low aerosol yield (< 10 particles s-1). Most surprisingly, other high-speed procedures, such as drilling and screwing, had low aerosol yields. Conclusion This work suggests that additional precautions should be recommended for diathermy and bone sawing, such as enhanced personal protective equipment or the use of suction devices to reduce exposure.
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Affiliation(s)
| | | | | | - Nick Maskell
- Bristol Medical School, University of Bristol, Bristol, UK
| | | | | | | | - James R. D. Murray
- Bristol Medical School, University of Bristol, Bristol, UK
- Avon Orthopaedic Centre, Southmead Hospital, North Bristol NHS Trust, Bristol, UK
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3
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Bain A, Chan MN, Bzdek BR. Physical properties of short chain aqueous organosulfate aerosol. Environ Sci Atmos 2023; 3:1365-1373. [PMID: 38013727 PMCID: PMC10500313 DOI: 10.1039/d3ea00088e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/08/2023] [Indexed: 11/29/2023]
Abstract
Organosulfates comprise up to 30% of the organic fraction of aerosol. Organosulfate aerosol physical properties, such as water activity, density, refractive index, and surface tension, are key to predicting their impact on global climate. However, current understanding of these properties is limited. Here, we measure the physical properties of aqueous solutions containing sodium methyl or ethyl sulfate and parameterise the data as a function of solute concentration. The experimental data are compared to available literature data for organosulfates, as well as salts (sodium sulfate and sodium bisulfate) and organics (short alkyl chain length alcohols and carboxylic acids) to determine if the physical properties of organosulfates can be approximated by molecules of similar functionality. With the exception of water activity, we find that organosulfates have intermediate physical properties between those of the salts and short alkyl chain organics. This work highlights the importance of measuring and developing models for the physical properties of abundant atmospheric organosulfates in order to better describe aerosol's impact on climate.
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Affiliation(s)
- Alison Bain
- School of Chemistry, University of Bristol Bristol UK
| | - Man Nin Chan
- Earth System Science Programme, Faculty of Science, The Chinese University of Hong Kong Hong Kong China
- The Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong Hong Kong China
| | - Bryan R Bzdek
- School of Chemistry, University of Bristol Bristol UK
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4
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Saccente-Kennedy B, Szczepanska A, Harrison J, Archer J, Watson NA, Orton CM, Costello D, Calder JD, Shah PL, Reid JP, Bzdek BR, Epstein R. Mitigation of Respirable Aerosol Particles from Speech and Language Therapy Exercises. J Voice 2023:S0892-1997(23)00124-8. [PMID: 37248120 DOI: 10.1016/j.jvoice.2023.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 04/05/2023] [Indexed: 05/31/2023]
Abstract
INTRODUCTION Phonation and speech are known sources of respirable aerosol in humans. Voice assessment and treatment manipulate all the subsystems of voice production, and previous work (Saccente-Kennedy et al., 2022) has demonstrated such activities can generate >10 times more aerosol than conversational speech and 30 times more aerosol than breathing. Aspects of voice therapy may therefore be considered aerosol generating procedures and pose a greater risk of potential airborne pathogen (eg, SARS-CoV-2) transmission than typical speech. Effective mitigation measures may be required to ensure safe service delivery for therapist and patient. OBJECTIVE To assess the effectiveness of mitigation measures in reducing detectable respirable aerosol produced by voice assessment/therapy. METHODS We recruited 15 healthy participants (8 cis-males, 7 cis-females), 9 of whom were voice-specialist speech-language pathologists. Optical Particle Sizers (OPS) (Model 3330, TSI) were used to measure the number concentration of respirable aerosol particles (0.3 µm-10 µm) generated during a selection of voice assessment/therapy tasks, both with and without mitigation measures in place. Measurements were performed in a laminar flow operating theatre, with near-zero background aerosol concentration, allowing us to quantify the number concentration of respiratory aerosol particles produced. Mitigation measures included the wearing of Type IIR fluid resistant surgical masks, wrapping the same masks around the end of straws, and the use of heat and moisture exchange microbiological filters (HMEFs) for a water resistance therapy (WRT) task. RESULTS All unmitigated therapy tasks produced more aerosol than unmasked breathing or speaking. Mitigation strategies reduced detectable aerosol from all tasks to a level significantly below, or no different to, that of unmasked breathing. Pooled filtration efficiencies determined that Type IIR surgical masks reduced detectable aerosol by 90%. Surgical masks wrapped around straws reduced detectable aerosol by 96%. HMEF filters were 100% effective in mitigating the aerosol from WRT, the exercise that generated more aerosol than any other task in the unmitigated condition. CONCLUSIONS Voice therapy and assessment causes the release of significant quantities of respirable aerosol. However, simple mitigation strategies can reduce emitted aerosol concentrations to levels comparable to unmasked breathing.
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Affiliation(s)
- Brian Saccente-Kennedy
- Department of Speech and Language Therapy (ENT), Royal National Ear, Nose and Throat and Eastman Dental Hospitals, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Alicja Szczepanska
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, United Kingdom
| | - Joshua Harrison
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, United Kingdom
| | - Justice Archer
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, United Kingdom
| | - Natalie A Watson
- Department of Ear, Nose and Throat Surgery, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Christopher M Orton
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom; Department of Respiratory Medicine, Chelsea and Westminster Hospital, London, United Kingdom; National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London, United Kingdom
| | - Declan Costello
- Ear, Nose and Throat Department, Wexham Park Hospital, United Kingdom
| | - James D Calder
- Department of Bioengineering, Imperial College London, United Kingdom; Fortius Clinic, Fitzhardinge St, London, United Kingdom
| | - Pallav L Shah
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom; Department of Respiratory Medicine, Chelsea and Westminster Hospital, London, United Kingdom; National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London, United Kingdom
| | - Jonathan P Reid
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, United Kingdom
| | - Bryan R Bzdek
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, United Kingdom
| | - Ruth Epstein
- Department of Speech and Language Therapy (ENT), Royal National Ear, Nose and Throat and Eastman Dental Hospitals, University College London Hospitals NHS Foundation Trust, London, United Kingdom.
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5
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Saccente-Kennedy B, Archer J, Symons HE, Watson NA, Orton CM, Browne WJ, Harrison J, Calder JD, Shah PL, Costello D, Reid JP, Bzdek BR, Epstein R. Quantification of Respirable Aerosol Particles from Speech and Language Therapy Exercises. J Voice 2022:S0892-1997(22)00207-7. [PMID: 36031505 DOI: 10.1016/j.jvoice.2022.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/05/2022] [Accepted: 07/06/2022] [Indexed: 10/15/2022]
Abstract
INTRODUCTION Voice assessment and treatment involve the manipulation of all the subsystems of voice production, and may lead to production of respirable aerosol particles that pose a greater risk of potential viral transmission via inhalation of respirable pathogens (eg, SARS-CoV-2) than quiet breathing or conversational speech. OBJECTIVE To characterise the production of respirable aerosol particles during a selection of voice assessment therapy tasks. METHODS We recruited 23 healthy adult participants (12 males, 11 females), 11 of whom were speech-language pathologists specialising in voice disorders. We used an aerodynamic and an optical particle sizer to measure the number concentration and particle size distributions of respirable aerosols generated during a variety of voice assessment and therapy tasks. The measurements were carried out in a laminar flow operating theatre, with a near-zero background aerosol concentration, allowing us to quantify the number concentration and size distributions of respirable aerosol particles produced from assessment/therapy tasks studied. RESULTS Aerosol number concentrations generated while performing assessment/therapy tasks were log-normally distributed among individuals with no significant differences between professionals (speech-language pathologists) and non-professionals or between males and females. Activities produced up to 32 times the aerosol number concentration of breathing and 24 times that of speech at 70-80 dBA. In terms of aerosol mass, activities produced up to 163 times the mass concentration of breathing and up to 36 times the mass concentration of speech. Voicing was a significant factor in aerosol production; aerosol number/mass concentrations generated during the voiced activities were 1.1-5 times higher than their unvoiced counterpart activities. Additionally, voiced activities produced bigger respirable aerosol particles than their unvoiced variants except the trills. Humming generated higher aerosol concentrations than sustained /a/, fricatives, speaking (70-80 dBA), and breathing. Oscillatory semi-occluded vocal tract exercises (SOVTEs) generated higher aerosol number/mass concentrations than the activities without oscillation. Water resistance therapy (WRT) generated the most aerosol of all activities, ∼10 times higher than speaking at 70-80 dBA and >30 times higher than breathing. CONCLUSIONS All activities generated more aerosol than breathing, although a sizeable minority were no different to speaking. Larger number concentrations and larger particle sizes appear to be generated by activities with higher suspected airflows, with the greatest involving intraoral pressure oscillation and/or an oscillating oral articulation (WRT or trilling).
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Affiliation(s)
- Brian Saccente-Kennedy
- Department of Speech and Language Therapy (ENT), Royal National Ear, Nose and Throat and Eastman Dental Hospitals, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Justice Archer
- School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Henry E Symons
- School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Natalie A Watson
- Department of Ear, Nose and Throat Surgery, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Christopher M Orton
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom; Department of Respiratory Medicine, Chelsea & Westminster Hospital, London, United Kingdom; National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London, United Kingdom
| | - William J Browne
- School of Education, University of Bristol, Bristol, United Kingdom
| | - Joshua Harrison
- School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - James D Calder
- Department of Bioengineering, Imperial College London, United Kingdom; Fortius Clinic, London, United Kingdom
| | - Pallav L Shah
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom; Department of Respiratory Medicine, Chelsea & Westminster Hospital, London, United Kingdom; National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London, United Kingdom
| | - Declan Costello
- Ear, Nose and Throat Department, Wexham Park Hospital, Slough, United Kingdom
| | - Jonathan P Reid
- School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Bryan R Bzdek
- School of Chemistry, University of Bristol, Bristol, United Kingdom.
| | - Ruth Epstein
- Department of Speech and Language Therapy (ENT), Royal National Ear, Nose and Throat and Eastman Dental Hospitals, University College London Hospitals NHS Foundation Trust, London, United Kingdom.
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6
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Gregson FKA, Shrimpton AJ, Hamilton F, Cook TM, Reid JP, Pickering AE, Pournaras DJ, Bzdek BR, Brown J. Identification of the source events for aerosol generation during oesophago-gastro-duodenoscopy. Gut 2022; 71:871-878. [PMID: 34187844 PMCID: PMC8245282 DOI: 10.1136/gutjnl-2021-324588] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 06/16/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To determine if oesophago-gastro-duodenoscopy (OGD) generates increased levels of aerosol in conscious patients and identify the source events. DESIGN A prospective, environmental aerosol monitoring study, undertaken in an ultraclean environment, on patients undergoing OGD. Sampling was performed 20 cm away from the patient's mouth using an optical particle sizer. Aerosol levels during OGD were compared with tidal breathing and voluntary coughs within subject. RESULTS Patients undergoing bariatric surgical assessment were recruited (mean body mass index 44 and mean age 40 years, n=15). A low background particle concentration in theatres (3 L-1) enabled detection of aerosol generation by tidal breathing (mean particle concentration 118 L-1). Aerosol recording during OGD showed an average particle number concentration of 595 L-1 with a wide range (3-4320 L-1). Bioaerosol-generating events, namely, coughing or burping, were common. Coughing was evoked in 60% of the endoscopies, with a greater peak concentration and a greater total number of sampled particles than the patient's reference voluntary coughs (11 710 vs 2320 L-1 and 780 vs 191 particles, n=9 and p=0.008). Endoscopies with coughs generated a higher level of aerosol than tidal breathing, whereas those without coughs were not different to the background. Burps also generated increased aerosol concentration, similar to those recorded during voluntary coughs. The insertion and removal of the endoscope were not aerosol generating unless a cough was triggered. CONCLUSION Coughing evoked during OGD is the main source of the increased aerosol levels, and therefore, OGD should be regarded as a procedure with high risk of producing respiratory aerosols. OGD should be conducted with airborne personal protective equipment and appropriate precautions in those patients who are at risk of having COVID-19 or other respiratory pathogens.
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Affiliation(s)
| | - Andrew J Shrimpton
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
| | - Fergus Hamilton
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Tim M Cook
- Department of Anaesthesia and Intensive Care Medicine, Royal United Hospitals NHS Trust, Bath, and Bristol Medical School, University of Bristol, Bristol, UK
| | | | - Anthony E Pickering
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
- Bristol Anaesthesia, Pain and Critical Care Sciences, Translational Health Sciences, Bristol Medical School, Bristol, UK
| | - Dimitri J Pournaras
- Department of Upper Gastrointestinal and Bariatric/Metabolic Surgery, North Bristol NHS Trust, Bristol, UK
| | - Bryan R Bzdek
- School of Chemistry, University of Bristol, Bristol, UK
| | - Jules Brown
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
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7
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Dudding T, Sheikh S, Gregson F, Haworth J, Haworth S, Main BG, Shrimpton AJ, Hamilton FW, Ireland AJ, Maskell NA, Reid JP, Bzdek BR, Gormley M. A clinical observational analysis of aerosol emissions from dental procedures. PLoS One 2022; 17:e0265076. [PMID: 35271682 PMCID: PMC8912243 DOI: 10.1371/journal.pone.0265076] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/22/2022] [Indexed: 12/27/2022] Open
Abstract
Aerosol generating procedures (AGPs) are defined as any procedure releasing airborne particles <5 μm in size from the respiratory tract. There remains uncertainty about which dental procedures constitute AGPs. We quantified the aerosol number concentration generated during a range of periodontal, oral surgery and orthodontic procedures using an aerodynamic particle sizer, which measures aerosol number concentrations and size distribution across the 0.5-20 μm diameter size range. Measurements were conducted in an environment with a sufficiently low background to detect a patient's cough, enabling confident identification of aerosol. Phantom head control experiments for each procedure were performed under the same conditions as a comparison. Where aerosol was detected during a patient procedure, we assessed whether the size distribution could be explained by the non-salivary contaminated instrument source in the respective phantom head control procedure using a two-sided unpaired t-test (comparing the mode widths (log(σ)) and peak positions (DP,C)). The aerosol size distribution provided a robust fingerprint of aerosol emission from a source. 41 patients underwent fifteen different dental procedures. For nine procedures, no aerosol was detected above background. Where aerosol was detected, the percentage of procedure time that aerosol was observed above background ranged from 12.7% for ultrasonic scaling, to 42.9% for 3-in-1 air + water syringe. For ultrasonic scaling, 3-in-1 syringe use and surgical drilling, the aerosol size distribution matched the non-salivary contaminated instrument source, with no unexplained aerosol. High and slow speed drilling produced aerosol from patient procedures with different size distributions to those measured from the phantom head controls (mode widths log(σ)) and peaks (DP,C, p< 0.002) and, therefore, may pose a greater risk of salivary contamination. This study provides evidence for sources of aerosol generation during common dental procedures, enabling more informed evaluation of risk and appropriate mitigation strategies.
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Affiliation(s)
- Tom Dudding
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Department of Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Bristol Dental Hospital and School, University of Bristol, Bristol, United Kingdom
| | - Sadiyah Sheikh
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Florence Gregson
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Jennifer Haworth
- Bristol Dental Hospital and School, University of Bristol, Bristol, United Kingdom
- Royal United Hospital Bath, Combe Park, Bath, United Kingdom
| | - Simon Haworth
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Department of Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Bristol Dental Hospital and School, University of Bristol, Bristol, United Kingdom
| | - Barry G. Main
- Department of Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Bristol Dental Hospital and School, University of Bristol, Bristol, United Kingdom
- Bristol Centre for Surgical Research, Population Health Sciences, Bristol Medical School, Bristol, United Kingdom
| | - Andrew J. Shrimpton
- School of Physiology, Pharmacology & Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Fergus W. Hamilton
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Department of Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Infection Sciences, Southmead Hospital, North Bristol NHS Trust, Bristol, United Kingdom
| | | | - Anthony J. Ireland
- Bristol Dental Hospital and School, University of Bristol, Bristol, United Kingdom
- Royal United Hospital Bath, Combe Park, Bath, United Kingdom
| | - Nick A. Maskell
- Academic Respiratory Unit, North Bristol NHS Trust, Bristol, United Kingdom
| | - Jonathan P. Reid
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Bryan R. Bzdek
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Mark Gormley
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Department of Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Bristol Dental Hospital and School, University of Bristol, Bristol, United Kingdom
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8
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Hamilton FW, Gregson FKA, Arnold DT, Sheikh S, Ward K, Brown J, Moran E, White C, Morley AJ, Bzdek BR, Reid JP, Maskell NA, Dodd JW. Aerosol emission from the respiratory tract: an analysis of aerosol generation from oxygen delivery systems. Thorax 2022. [PMID: 34737195 DOI: 10.1101/2021.01.29.21250552] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
INTRODUCTION continuous positive airway pressure (CPAP) and high-flow nasal oxygen (HFNO) provide enhanced oxygen delivery and respiratory support for patients with severe COVID-19. CPAP and HFNO are currently designated as aerosol-generating procedures despite limited high-quality experimental data. We aimed to characterise aerosol emission from HFNO and CPAP and compare with breathing, speaking and coughing. MATERIALS AND METHODS Healthy volunteers were recruited to breathe, speak and cough in ultra-clean, laminar flow theatres followed by using CPAP and HFNO. Aerosol emission was measured using two discrete methodologies, simultaneously. Hospitalised patients with COVID-19 had cough recorded using the same methodology on the infectious diseases ward. RESULTS In healthy volunteers (n=25 subjects; 531 measures), CPAP (with exhalation port filter) produced less aerosol than breathing, speaking and coughing (even with large >50 L/min face mask leaks). Coughing was associated with the highest aerosol emissions of any recorded activity. HFNO was associated with aerosol emission, however, this was from the machine. Generated particles were small (<1 µm), passing from the machine through the patient and to the detector without coalescence with respiratory aerosol, thereby unlikely to carry viral particles. More aerosol was generated in cough from patients with COVID-19 (n=8) than volunteers. CONCLUSIONS In healthy volunteers, standard non-humidified CPAP is associated with less aerosol emission than breathing, speaking or coughing. Aerosol emission from the respiratory tract does not appear to be increased by HFNO. Although direct comparisons are complex, cough appears to be the main aerosol-generating risk out of all measured activities.
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Affiliation(s)
- Fergus W Hamilton
- Infection Science, North Bristol NHS Trust, Westbury on Trym, UK
- MRC Integrative Epidemiology Unit, Bristol, UK
| | - Florence K A Gregson
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - David T Arnold
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
| | - Sadiyah Sheikh
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Kirsty Ward
- Physiotherapy Department, North Bristol NHS Trust, Westbury on Trym, UK
| | - Jules Brown
- Anaesthetics and Intensive Care Department, North Bristol NHS Trust, Westbury on Trym, UK
| | - Ed Moran
- Infectious Diseases, North Bristol NHS Trust, Bristol, UK
| | - Carrie White
- Research and Development, North Bristol NHS Trust, Westbury on Trym, UK
| | - Anna J Morley
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
| | - Bryan R Bzdek
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Jonathan P Reid
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Nicholas A Maskell
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
| | - James William Dodd
- MRC Integrative Epidemiology Unit, Bristol, UK
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
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9
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Archer J, McCarthy LP, Symons HE, Watson NA, Orton CM, Browne WJ, Harrison J, Moseley B, Philip KEJ, Calder JD, Shah PL, Bzdek BR, Costello D, Reid JP. Comparing aerosol number and mass exhalation rates from children and adults during breathing, speaking and singing. Interface Focus 2022; 12:20210078. [PMID: 35261733 PMCID: PMC8831083 DOI: 10.1098/rsfs.2021.0078] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 01/04/2022] [Indexed: 12/14/2022] Open
Abstract
Aerosol particles of respirable size are exhaled when individuals breathe, speak and sing and can transmit respiratory pathogens between infected and susceptible individuals. The COVID-19 pandemic has brought into focus the need to improve the quantification of the particle number and mass exhalation rates as one route to provide estimates of viral shedding and the potential risk of transmission of viruses. Most previous studies have reported the number and mass concentrations of aerosol particles in an exhaled plume. We provide a robust assessment of the absolute particle number and mass exhalation rates from measurements of minute ventilation using a non-invasive Vyntus Hans Rudolf mask kit with straps housing a rotating vane spirometer along with measurements of the exhaled particle number concentrations and size distributions. Specifically, we report comparisons of the number and mass exhalation rates for children (12–14 years old) and adults (19–72 years old) when breathing, speaking and singing, which indicate that child and adult cohorts generate similar amounts of aerosol when performing the same activity. Mass exhalation rates are typically 0.002–0.02 ng s
−1
from breathing, 0.07–0.2 ng s
−1
from speaking (at 70–80 dBA) and 0.1–0.7 ng s
−1
from singing (at 70–80 dBA). The aerosol exhalation rate increases with increasing sound volume for both children and adults when both speaking and singing.
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Affiliation(s)
| | | | | | - Natalie A. Watson
- Department of Ear, Nose and Throat Surgery, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Christopher M. Orton
- Department of Respiratory Medicine, Royal Brompton Hospital, London, UK
- Department of Respiratory Medicine, Chelsea and Westminster Hospital, London, UK
- National Heart and Lung Institute, Imperial College London, Guy Scadding Building, London, UK
| | | | | | - Benjamin Moseley
- Department of Respiratory Medicine, Chelsea and Westminster Hospital, London, UK
| | - Keir E. J. Philip
- Department of Respiratory Medicine, Royal Brompton Hospital, London, UK
- National Heart and Lung Institute, Imperial College London, Guy Scadding Building, London, UK
| | - James D. Calder
- Department of Bioengineering, Imperial College London, London, UK
- Fortius Clinic, Fitzhardinge Street, London, UK
| | - Pallav L. Shah
- Department of Respiratory Medicine, Royal Brompton Hospital, London, UK
- Department of Respiratory Medicine, Chelsea and Westminster Hospital, London, UK
- National Heart and Lung Institute, Imperial College London, Guy Scadding Building, London, UK
| | | | - Declan Costello
- Ear, Nose and Throat Department, Wexham Park Hospital, Slough, UK
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10
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Shrimpton AJ, Gregson FKA, Brown JM, Cook TM, Bzdek BR, Hamilton F, Reid JP, Pickering AE. A quantitative evaluation of aerosol generation during supraglottic airway insertion and removal. Anaesthesia 2021; 76:1577-1584. [PMID: 34287820 DOI: 10.1111/anae.15542] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2021] [Indexed: 12/30/2022]
Abstract
Many guidelines consider supraglottic airway use to be an aerosol-generating procedure. This status requires increased levels of personal protective equipment, fallow time between cases and results in reduced operating theatre efficiency. Aerosol generation has never been quantitated during supraglottic airway use. To address this evidence gap, we conducted real-time aerosol monitoring (0.3-10-µm diameter) in ultraclean operating theatres during supraglottic airway insertion and removal. This showed very low background particle concentrations (median (IQR [range]) 1.6 (0-3.1 [0-4.0]) particles.l-1 ) against which the patient's tidal breathing produced a higher concentration of aerosol (4.0 (1.3-11.0 [0-44]) particles.l-1 , p = 0.048). The average aerosol concentration detected during supraglottic airway insertion (1.3 (1.0-4.2 [0-6.2]) particles.l-1 , n = 11), and removal (2.1 (0-17.5 [0-26.2]) particles.l-1 , n = 12) was no different to tidal breathing (p = 0.31 and p = 0.84, respectively). Comparison of supraglottic airway insertion and removal with a volitional cough (104 (66-169 [33-326]), n = 27), demonstrated that supraglottic airway insertion/removal sequences produced <4% of the aerosol compared with a single cough (p < 0.001). A transient aerosol increase was recorded during one complicated supraglottic airway insertion (which initially failed to provide a patent airway). Detailed analysis of this event showed an atypical particle size distribution and we subsequently identified multiple sources of non-respiratory aerosols that may be produced during airway management and can be considered as artefacts. These findings demonstrate supraglottic airway insertion/removal generates no more bio-aerosol than breathing and far less than a cough. This should inform the design of infection prevention strategies for anaesthetists and operating theatre staff caring for patients managed with supraglottic airways.
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Affiliation(s)
- A J Shrimpton
- Pain and Critical Care Sciences and School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - F K A Gregson
- School of Chemistry, University of Bristol, Bristol, UK
| | - J M Brown
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
| | - T M Cook
- Department of Anaesthesia and Intensive Care Medicine, Royal United Hospital NHS Trust, Bath, UK
| | - B R Bzdek
- School of Chemistry, University of Bristol, Bristol, UK
| | - F Hamilton
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - J P Reid
- School of Chemistry, University of Bristol, Bristol, UK
| | - A E Pickering
- Pain and Critical Care Sciences and School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
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11
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Hamilton FW, Gregson FKA, Arnold DT, Sheikh S, Ward K, Brown J, Moran E, White C, Morley AJ, Bzdek BR, Reid JP, Maskell NA, Dodd JW. Aerosol emission from the respiratory tract: an analysis of aerosol generation from oxygen delivery systems. Thorax 2021; 77:276-282. [PMID: 34737195 PMCID: PMC8867281 DOI: 10.1136/thoraxjnl-2021-217577] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 10/17/2021] [Indexed: 11/05/2022]
Abstract
Introduction continuous positive airway pressure (CPAP) and high-flow nasal oxygen (HFNO) provide enhanced oxygen delivery and respiratory support for patients with severe COVID-19. CPAP and HFNO are currently designated as aerosol-generating procedures despite limited high-quality experimental data. We aimed to characterise aerosol emission from HFNO and CPAP and compare with breathing, speaking and coughing. Materials and methods Healthy volunteers were recruited to breathe, speak and cough in ultra-clean, laminar flow theatres followed by using CPAP and HFNO. Aerosol emission was measured using two discrete methodologies, simultaneously. Hospitalised patients with COVID-19 had cough recorded using the same methodology on the infectious diseases ward. Results In healthy volunteers (n=25 subjects; 531 measures), CPAP (with exhalation port filter) produced less aerosol than breathing, speaking and coughing (even with large >50 L/min face mask leaks). Coughing was associated with the highest aerosol emissions of any recorded activity. HFNO was associated with aerosol emission, however, this was from the machine. Generated particles were small (<1 µm), passing from the machine through the patient and to the detector without coalescence with respiratory aerosol, thereby unlikely to carry viral particles. More aerosol was generated in cough from patients with COVID-19 (n=8) than volunteers. Conclusions In healthy volunteers, standard non-humidified CPAP is associated with less aerosol emission than breathing, speaking or coughing. Aerosol emission from the respiratory tract does not appear to be increased by HFNO. Although direct comparisons are complex, cough appears to be the main aerosol-generating risk out of all measured activities.
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Affiliation(s)
- Fergus W Hamilton
- Infection Science, North Bristol NHS Trust, Westbury on Trym, UK .,MRC Integrative Epidemiology Unit, Bristol, UK
| | - Florence K A Gregson
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - David T Arnold
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
| | - Sadiyah Sheikh
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Kirsty Ward
- Physiotherapy Department, North Bristol NHS Trust, Westbury on Trym, UK
| | - Jules Brown
- Anaesthetics and Intensive Care Department, North Bristol NHS Trust, Westbury on Trym, UK
| | - Ed Moran
- Infectious Diseases, North Bristol NHS Trust, Bristol, UK
| | - Carrie White
- Research and Development, North Bristol NHS Trust, Westbury on Trym, UK
| | - Anna J Morley
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
| | | | - Bryan R Bzdek
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Jonathan P Reid
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Nicholas A Maskell
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
| | - James William Dodd
- MRC Integrative Epidemiology Unit, Bristol, UK.,Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
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12
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Sheikh S, Hamilton FW, Nava GW, Gregson FKA, Arnold DT, Riley C, Brown J, Reid JP, Bzdek BR, Maskell NA, Dodd JW. Are aerosols generated during lung function testing in patients and healthy volunteers? Results from the AERATOR study. Thorax 2021; 77:292-294. [PMID: 34728573 DOI: 10.1136/thoraxjnl-2021-217671] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 08/12/2021] [Indexed: 11/03/2022]
Abstract
Pulmonary function tests are fundamental to the diagnosis and monitoring of respiratory diseases. There is uncertainty around whether potentially infectious aerosols are produced during testing and there are limited data on mitigation strategies to reduce risk to staff. Healthy volunteers and patients with lung disease underwent standardised spirometry, peak flow and FENO assessments. Aerosol number concentration was sampled using an aerodynamic particle sizer and an optical particle sizer. Measured aerosol concentrations were compared with breathing, speaking and voluntary coughing. Mitigation strategies included a standard viral filter and a full-face mask normally used for exercise testing (to mitigate induced coughing). 147 measures were collected from 33 healthy volunteers and 10 patients with lung disease. The aerosol number concentration was highest in coughs (1.45-1.61 particles/cm3), followed by unfiltered peak flow (0.37-0.76 particles/cm3). Addition of a viral filter to peak flow reduced aerosol emission by a factor of 10 without affecting the results. On average, coughs produced 22 times more aerosols than standard spirometry (with filter) in patients and 56 times more aerosols in healthy volunteers. FENO measurement produced negligible aerosols. Cardiopulmonary exercise test (CPET) masks reduced aerosol emission when breathing, speaking and coughing significantly. Lung function testing produces less aerosols than voluntary coughing. CPET masks may be used to reduce aerosol emission from induced coughing. Standard viral filters are sufficiently effective to allow guidelines to remove lung function testing from the list of aerosol-generating procedures.
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Affiliation(s)
- Sadiyah Sheikh
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Fergus W Hamilton
- Department of Infection Science, North Bristol NHS Trust, Bristol, UK .,Population Health Sciences, University of Bristol, Bristol, UK.,MRC Integrative Epidemiology Unit, Bristol, UK
| | - George W Nava
- Academic Respiratory Unit, University of Bristol, Bristol, UK
| | - Florence K A Gregson
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - David T Arnold
- Academic Respiratory Unit, University of Bristol, Bristol, UK
| | - Colleen Riley
- Respiratory Physiology, North Bristol NHS Trust, Westbury on Trym, UK
| | - Jules Brown
- Anaesthetics and Intensive Care Department, North Bristol NHS Trust, Westbury on Trym, UK
| | | | - Jonathan P Reid
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Bryan R Bzdek
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Nicholas A Maskell
- North Bristol Lung Centre, Southmead Hospital, Bristol, UK.,Academic Respiratory Unit, Department of Clinical Sciences, Bristol University, Bristol, UK
| | - James William Dodd
- Academic Respiratory Unit, North Bristol NHS Trust, Westbury on Trym, UK
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13
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Arnold DT, Gregson FKA, Sheikh S, Hamilton FW, Welch H, Dipper A, Nava GW, Dodd JW, Clive AO, Bzdek BR, Reid JP, Maskell NA. Standard pleural interventions are not high-risk aerosol generating procedures. Eur Respir J 2021; 58:2101064. [PMID: 34244318 PMCID: PMC8555490 DOI: 10.1183/13993003.01064-2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/14/2021] [Indexed: 11/30/2022]
Abstract
The nosocomial spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has focused attention on the risk of aerosol generating procedures (AGPs) in healthcare [1]. SARS-CoV-2 has been isolated from pleural fluid, which has the potential to infect staff or patients if viraemic fluid is aerosolised during procedures [2, 3]. However, evidence for aerosol generation from pleural procedures is very limited. Current guidelines for appropriate use of personal protective equipment (PPE) while performing pleural procedures are based on expert opinion and application of the precautionary principle [4]. We set out to quantify if pleural procedures generated appreciable aerosol (aerosolised liquid particles that have the potential to carry virus) compared to aerosol sampled during normal respiratory activities of breathing and coughing. Percutaneous pleural procedures should not be considered aerosol generating. This study should inform future iterations of guidelines on the appropriate use of PPE when performing these procedures. https://bit.ly/3xFF71d
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Affiliation(s)
- David T Arnold
- Academic Respiratory Unit, University of Bristol, Bristol, UK
| | - Florence K A Gregson
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Sadiyah Sheikh
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Fergus W Hamilton
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
- Infection Sciences, North Bristol NHS Trust, Bristol, UK
| | - Hugh Welch
- Academic Respiratory Unit, University of Bristol, Bristol, UK
| | | | - George W Nava
- Academic Respiratory Unit, University of Bristol, Bristol, UK
| | - James W Dodd
- Academic Respiratory Unit, University of Bristol, Bristol, UK
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol, UK
| | - Amelia O Clive
- Academic Respiratory Unit, University of Bristol, Bristol, UK
| | - Bryan R Bzdek
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Jonathan P Reid
- Bristol Aerosol Research Centre, School of Chemistry, University of Bristol, Bristol, UK
| | - Nick A Maskell
- Academic Respiratory Unit, University of Bristol, Bristol, UK
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14
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Gregson FKA, Watson NA, Orton CM, Haddrell AE, McCarthy LP, Finnie TJR, Gent N, Donaldson GC, Shah PL, Calder JD, Bzdek BR, Costello D, Reid JP. Comparing aerosol concentrations and particle size distributions generated by singing, speaking and breathing. Aerosol Science and Technology 2021. [PMID: 0 DOI: 10.1080/02786826.2021.1883544] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Affiliation(s)
| | - Natalie A. Watson
- Department of Ear, Nose and Throat Surgery, Lewisham and Greenwich NHS Trust, London, United Kingdom
| | - Christopher M. Orton
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom
- Department of Respiratory Medicine, Chelsea & Westminster Hospital, London, United Kingdom
- National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London, United Kingdom
| | | | | | - Thomas J. R. Finnie
- Emergency Response Department Science and Technology (ERD S&T), Health Protection Directorate, Public Health England, Salisbury, Wiltshire, United Kingdom
| | - Nick Gent
- Emergency Response Department Science and Technology (ERD S&T), Health Protection Directorate, Public Health England, Salisbury, Wiltshire, United Kingdom
| | - Gavin. C. Donaldson
- National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London, United Kingdom
| | - Pallav L. Shah
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom
- Department of Respiratory Medicine, Chelsea & Westminster Hospital, London, United Kingdom
- National Heart and Lung Institute, Guy Scadding Building, Imperial College London, London, United Kingdom
| | - James D. Calder
- Department of Bioengineering, Imperial College London, United Kingdom
- Fortius Clinic, London, UK
| | - Bryan R. Bzdek
- School of Chemistry, University of Bristol, Bristol, United Kingdom
| | - Declan Costello
- Ear, Nose and Throat Department, Wexham Park Hospital, United Kingdom
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol, United Kingdom
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15
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Hamilton F, Arnold D, Bzdek BR, Dodd J, Reid J, Maskell N. Aerosol generating procedures: are they of relevance for transmission of SARS-CoV-2? Lancet Respir Med 2021; 9:687-689. [PMID: 33965002 PMCID: PMC8102043 DOI: 10.1016/s2213-2600(21)00216-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/16/2022]
Affiliation(s)
- Fergus Hamilton
- MRC Integrative Epidemiology Unit, University of Bristol, Bristol UK
| | - David Arnold
- Academic Respiratory Unit, University of Bristol, Bristol BS10 5NB, UK
| | - Bryan R Bzdek
- Bristol Aerosol Research Centre, University of Bristol, Bristol, UK
| | - James Dodd
- Academic Respiratory Unit, University of Bristol, Bristol BS10 5NB, UK
| | | | - Jonathan Reid
- Academic Respiratory Unit, University of Bristol, Bristol BS10 5NB, UK; Bristol Aerosol Research Centre, University of Bristol, Bristol, UK
| | - Nick Maskell
- Academic Respiratory Unit, University of Bristol, Bristol BS10 5NB, UK.
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16
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Newsom RB, Amara A, Hicks A, Quint M, Pattison C, Bzdek BR, Burridge J, Krawczyk C, Dinsmore J, Conway J. Comparison of droplet spread in standard and laminar flow operating theatres: SPRAY study group. J Hosp Infect 2021; 110:194-200. [PMID: 33549768 PMCID: PMC7860961 DOI: 10.1016/j.jhin.2021.01.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/20/2021] [Accepted: 01/26/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND Reducing COVID-19 transmission relies on controlling droplet and aerosol spread. Fluorescein staining reveals microscopic droplets. AIM To compare the droplet spread in non-laminar and laminar air flow operating theatres. METHODS A 'cough-generator' was fixed to a theatre trolley at 45°. Fluorescein-stained 'secretions' were projected on to a series of calibrated targets. These were photographed under UV light and 'source detection' software measured droplet splatter size and distance. FINDINGS The smallest droplet detected was ∼120 μm and the largest ∼24,000 μm. An average of 25,862 spots was detected in the non-laminar theatre, compared with 11,430 in the laminar theatre (56% reduction). The laminar air flow mainly affected the smaller droplets (<1000 μm). The surface area covered with droplets was: 6% at 50 cm, 1% at 2 m, and 0.5% at 3 m in the non-laminar air flow; and 3%, 0.5%, and 0.2% in the laminar air flow, respectively. CONCLUSION Accurate mapping of droplet spread in clinical environments is possible using fluorescein staining and image analysis. The laminar air flow affected the smaller droplets but had limited effect on larger droplets in our 'aerosol-generating procedure' cough model. Our results indicate that the laminar air flow theatre requires similar post-surgery cleaning to the non-laminar, and staff should consider full personal protective equipment for medium- and high-risk patients.
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Affiliation(s)
- R B Newsom
- School of Health and Care Professions, University of Portsmouth, Portsmouth, UK.
| | - A Amara
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, UK
| | - A Hicks
- Respiratory Medicine, Portsmouth Hospitals University NHS Trust, UK
| | - M Quint
- Respiratory Physiotherapy, Portsmouth Hospitals University NHS Trust, UK
| | - C Pattison
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, UK
| | - B R Bzdek
- NERC, School of Chemistry, University of Bristol, UK
| | - J Burridge
- School of Mathematics, University of Portsmouth, UK
| | - C Krawczyk
- Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, UK
| | - J Dinsmore
- Anaesthesia, Portsmouth Hospitals University NHS Trust, UK
| | - J Conway
- Respiratory Sciences, Brunel University, London, UK
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17
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Walker JS, Archer J, Gregson FKA, Michel SES, Bzdek BR, Reid JP. Correction to "Accurate Representations of the Microphysical Processes Occurring during the Transport of Exhaled Aerosols and Droplets". ACS Cent Sci 2021; 7:507. [PMID: 33791432 PMCID: PMC8006164 DOI: 10.1021/acscentsci.1c00220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Indexed: 06/12/2023]
Abstract
[This corrects the article DOI: 10.1021/acscentsci.0c01522.].
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18
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Walker JS, Archer J, Gregson FKA, Michel SES, Bzdek BR, Reid JP. Accurate Representations of the Microphysical Processes Occurring during the Transport of Exhaled Aerosols and Droplets. ACS Cent Sci 2021; 7:200-209. [PMID: 33532579 PMCID: PMC7845015 DOI: 10.1021/acscentsci.0c01522] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Indexed: 05/19/2023]
Abstract
Aerosols and droplets from expiratory events play an integral role in transmitting pathogens such as SARS-CoV-2 from an infected individual to a susceptible host. However, there remain significant uncertainties in our understanding of the aerosol droplet microphysics occurring during drying and sedimentation and the effect on the sedimentation outcomes. Here, we apply a new treatment for the microphysical behavior of respiratory fluid droplets to a droplet evaporation/sedimentation model and assess the impact on sedimentation distance, time scale, and particle phase. Above a 100 μm initial diameter, the sedimentation outcome for a respiratory droplet is insensitive to composition and ambient conditions. Below 100 μm, and particularly below 80 μm, the increased settling time allows the exact nature of the evaporation process to play a significant role in influencing the sedimentation outcome. For this size range, an incorrect treatment of the droplet composition, or imprecise use of RH or temperature, can lead to large discrepancies in sedimentation distance (with representative values >1 m, >2 m, and >2 m, respectively). Additionally, a respiratory droplet is likely to undergo a phase change prior to sedimenting if initially <100 μm in diameter, provided that the RH is below the measured phase change RH. Calculations of the potential exposure versus distance from the infected source show that the volume fraction of the initial respiratory droplet distribution, in this size range, which remains elevated above 1 m decreases from 1 at 1 m to 0.125 at 2 m.
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Affiliation(s)
- Jim S. Walker
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Justice Archer
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | | | - Sarah E. S. Michel
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Bryan R. Bzdek
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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19
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Shrimpton A, Gregson FKA, Cook TM, Brown J, Bzdek BR, Reid JP, Pickering AE. A quantitative evaluation of aerosol generation during tracheal intubation and extubation: a reply. Anaesthesia 2020; 76 Suppl 3:16-18. [PMID: 33368170 DOI: 10.1111/anae.15345] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2020] [Indexed: 11/26/2022]
Affiliation(s)
- A Shrimpton
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - F K A Gregson
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - T M Cook
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - J Brown
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - B R Bzdek
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - J P Reid
- University of Bristol and North Bristol NHS Trust, Bristol, UK
| | - A E Pickering
- University of Bristol and North Bristol NHS Trust, Bristol, UK
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20
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Brown J, Gregson FKA, Shrimpton A, Cook TM, Bzdek BR, Reid JP, Pickering AE. A quantitative evaluation of aerosol generation during tracheal intubation and extubation. Anaesthesia 2020; 76:174-181. [PMID: 33022093 PMCID: PMC7675579 DOI: 10.1111/anae.15292] [Citation(s) in RCA: 129] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2020] [Indexed: 12/18/2022]
Abstract
The potential aerosolised transmission of severe acute respiratory syndrome coronavirus‐2 is of global concern. Airborne precaution personal protective equipment and preventative measures are universally mandated for medical procedures deemed to be aerosol generating. The implementation of these measures is having a huge impact on healthcare provision. There is currently a lack of quantitative evidence on the number and size of airborne particles produced during aerosol‐generating procedures to inform risk assessments. To address this evidence gap, we conducted real‐time, high‐resolution environmental monitoring in ultraclean ventilation operating theatres during tracheal intubation and extubation sequences. Continuous sampling with an optical particle sizer allowed characterisation of aerosol generation within the zone between the patient and anaesthetist. Aerosol monitoring showed a very low background particle count (0.4 particles.l−1) allowing resolution of transient increases in airborne particles associated with airway management. As a positive reference control, we quantitated the aerosol produced in the same setting by a volitional cough (average concentration, 732 (418) particles.l−1, n = 38). Tracheal intubation including facemask ventilation produced very low quantities of aerosolised particles (average concentration, 1.4 (1.4) particles.l−1, n = 14, p < 0.0001 vs. cough). Tracheal extubation, particularly when the patient coughed, produced a detectable aerosol (21 (18) l−1, n = 10) which was 15‐fold greater than intubation (p = 0.0004) but 35‐fold less than a volitional cough (p < 0.0001). The study does not support the designation of elective tracheal intubation as an aerosol‐generating procedure. Extubation generates more detectable aerosol than intubation but falls below the current criterion for designation as a high‐risk aerosol‐generating procedure. These novel findings from real‐time aerosol detection in a routine healthcare setting provide a quantitative methodology for risk assessment that can be extended to other airway management techniques and clinical settings. They also indicate the need for reappraisal of what constitutes an aerosol‐generating procedure and the associated precautions for routine anaesthetic airway management.
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Affiliation(s)
- J Brown
- Department of Anaesthesia and Intensive Care Medicine, North Bristol NHS Trust, Bristol, UK
| | - F K A Gregson
- School of Chemistry, University of Bristol, Bristol, UK
| | - A Shrimpton
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - T M Cook
- Department of Anaesthesia and Intensive Care Medicine, Royal United Hospital NHS Trust, Bath, UK
| | - B R Bzdek
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - J P Reid
- School of Chemistry, University of Bristol, Bristol, UK
| | - A E Pickering
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK.,University Hospitals Bristol, Bristol, UK
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21
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Abstract
Aerosols are highly dynamic, non-equilibrium systems exhibiting unique microphysical properties relative to bulk systems. Here the authors discuss the roles aerosols play in (bio)chemical transformations and identify open questions in aerosol-mediated reaction rate accelerations, aerosol optical properties, and microorganism survival.
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Affiliation(s)
- Bryan R. Bzdek
- grid.5337.20000 0004 1936 7603School of Chemistry, University of Bristol, Bristol, BS8 1TS UK
| | - Jonathan P. Reid
- grid.5337.20000 0004 1936 7603School of Chemistry, University of Bristol, Bristol, BS8 1TS UK
| | - Michael I. Cotterell
- grid.5337.20000 0004 1936 7603School of Chemistry, University of Bristol, Bristol, BS8 1TS UK
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22
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Miles REH, Glerum MWJ, Boyer HC, Walker JS, Dutcher CS, Bzdek BR. Surface Tensions of Picoliter Droplets with Sub-Millisecond Surface Age. J Phys Chem A 2019; 123:3021-3029. [PMID: 30864798 DOI: 10.1021/acs.jpca.9b00903] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Aerosols are key components of the atmosphere and play important roles in many industrial processes. Because aerosol particles have high surface-to-volume ratios, their surface properties are especially important. However, direct measurement of the surface properties of aerosol particles is challenging. In this work, we describe an approach to measure the surface tension of picoliter volume droplets with surface age <1 ms by resolving their dynamic oscillations in shape immediately after ejection from a microdroplet dispenser. Droplet shape oscillations are monitored by highly time-resolved (500 ns) stroboscopic imaging, and droplet surface tension is accurately retrieved across a wide range of droplet sizes (10-25 μm radius) and surface ages (down to ∼100 μs). The approach is validated for droplets containing sodium chloride, glutaric acid, and water, which all show no variation in surface tension with surface age. Experimental results from the microdroplet dispenser approach are compared to complementary surface tension measurements of 5-10 μm radius droplets with aged surfaces using a holographic optical tweezers approach and predictions of surface tension using a statistical thermodynamic model. These approaches combined will allow investigation of droplet surface tension across a wide range of droplet sizes, compositions, and surface ages.
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Affiliation(s)
- Rachael E H Miles
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
| | - Michael W J Glerum
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
| | - Hallie C Boyer
- Department of Mechanical Engineering , University of Minnesota, Twin Cities , Minneapolis , Minnesota 55455 , United States
| | - Jim S Walker
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
| | - Cari S Dutcher
- Department of Mechanical Engineering , University of Minnesota, Twin Cities , Minneapolis , Minnesota 55455 , United States
| | - Bryan R Bzdek
- School of Chemistry , University of Bristol , Cantock's Close , Bristol BS8 1TS , United Kingdom
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Marsh A, Rovelli G, Song YC, Pereira KL, Willoughby RE, Bzdek BR, Hamilton JF, Orr-Ewing AJ, Topping DO, Reid JP. Accurate representations of the physicochemical properties of atmospheric aerosols: when are laboratory measurements of value? Faraday Discuss 2018; 200:639-661. [PMID: 28574570 DOI: 10.1039/c7fd00008a] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Laboratory studies can provide important insights into the processes that occur at the scale of individual particles in ambient aerosol. We examine the accuracies of measurements of core physicochemical properties of aerosols that can be made in single particle studies and explore the impact of these properties on the microscopic processes that occur in ambient aerosol. Presenting new measurements, we examine here the refinements in our understanding of aerosol hygroscopicity, surface tension, viscosity and optical properties that can be gained from detailed laboratory measurements for complex mixtures through to surrogates for secondary organic atmospheric aerosols.
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Affiliation(s)
- Bryan R. Bzdek
- School of Chemistry, University of Bristol, Bristol BS8 1TS,
United Kingdom
| | - Jonathan P. Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS,
United Kingdom
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Abstract
Atmospheric aerosols impact global climate either directly by scattering solar radiation or indirectly by serving as cloud condensation nuclei, which influence cloud albedo and precipitation patterns. Our scientific understanding of these impacts is poor relative to that of, for instance, greenhouse gases, in part because it is difficult to predict particle number concentrations. One important pathway by which particles are added to the atmosphere is new particle formation, where gas phase precursors form molecular clusters that subsequently grow to the climatically relevant size range (50-100 nm diameter). It is predicted that up to 50% of atmospheric particles arise from this process, but the key initial chemical processes are poorly resolved. In general, a combination of inorganic and organic molecules are thought to contribute to new particle formation, but the chemical composition of molecular clusters and pathways by which they grow to larger sizes is unclear. Cluster growth is a key component of new particle formation, as it governs whether molecular clusters will become climatically relevant. This Account discusses our recent work to understand the mechanisms underlying new particle growth. Atmospherically relevant molecular clusters containing the likely key contributors to new particle formation (sulfuric acid, ammonia, amines, and water) were investigated experimentally by Fourier transform mass spectrometry as well as computationally by density functional theory. Our laboratory experiments investigated the molecular composition of charged clusters, the molecular pathways by which these clusters may grow, and the kinetics of base incorporation into them. Computational chemistry allowed confirmation and rationalization of the experimental results for charged clusters and extension of these principles to uncharged and hydrated clusters that are difficult to study by mass spectrometry. This combination of approaches enabled us to establish a framework for cluster growth involving sulfuric acid, ammonia, amines, and water. Charged or uncharged, cluster growth occurs primarily through an ammonium (or aminium) bisulfate coordinate. In these clusters, proton transfer is maximized between acids and bases to produce cations (ammonium, aminium) and anions (bisulfate), whereas additional molecules (water and unneutralized sulfuric acid) remain un-ionized. Experimental measurements suggest the growth of positively charged clusters occurs by successive acidification and neutralization steps. The acidification step is nearly barrierless, whereas the neutralization step exhibits a significant activation barrier in the case of ammonia. Bases are also incorporated into these clusters by displacement of one base for another. Base displacement is barrierless on the cluster surface but not within the cluster core. The favorability of amines relative to ammonia in charged clusters is governed by the trade-off between gas phase basicity and binding energetics. Computational studies indicate that water has a relatively small effect on cluster energetics. In short, amines are effective at assisting the formation and initial growth of clusters but become less important as cluster size increases, especially when hydration is considered. More generally, this work shows how experiment and computation can provide important, complementary information to address problems of environmental interest.
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Affiliation(s)
- Bryan R. Bzdek
- Department of Chemistry and
Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Joseph W. DePalma
- Department of Chemistry and
Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Murray V. Johnston
- Department of Chemistry and
Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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Haddrell AE, Miles REH, Bzdek BR, Reid JP, Hopkins RJ, Walker JS. Coalescence Sampling and Analysis of Aerosols using Aerosol Optical Tweezers. Anal Chem 2017; 89:2345-2352. [DOI: 10.1021/acs.analchem.6b03979] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Allen E. Haddrell
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | | | - Bryan R. Bzdek
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Jonathan P. Reid
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Rebecca J. Hopkins
- Defence Science and Technology Laboratory (DSTL), Porton Down, Salisbury SP4 0JQ, United Kingdom
| | - Jim S. Walker
- Bristol Industrial and Research Associates Ltd (BIRAL), Unit 8 Harbour Road Trading Estate, Portishead, Bristol BS20 7BL, United Kingdom
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27
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Bzdek BR, Collard L, Sprittles JE, Hudson AJ, Reid JP. Dynamic measurements and simulations of airborne picolitre-droplet coalescence in holographic optical tweezers. J Chem Phys 2017; 145:054502. [PMID: 27497560 DOI: 10.1063/1.4959901] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We report studies of the coalescence of pairs of picolitre aerosol droplets manipulated with holographic optical tweezers, probing the shape relaxation dynamics following coalescence by simultaneously monitoring the intensity of elastic backscattered light (EBL) from the trapping laser beam (time resolution on the order of 100 ns) while recording high frame rate camera images (time resolution <10 μs). The goals of this work are to: resolve the dynamics of droplet coalescence in holographic optical traps; assign the origin of key features in the time-dependent EBL intensity; and validate the use of the EBL alone to precisely determine droplet surface tension and viscosity. For low viscosity droplets, two sequential processes are evident: binary coalescence first results from the overlap of the optical traps on the time scale of microseconds followed by the recapture of the composite droplet in an optical trap on the time scale of milliseconds. As droplet viscosity increases, the relaxation in droplet shape eventually occurs on the same time scale as recapture, resulting in a convoluted evolution of the EBL intensity that inhibits quantitative determination of the relaxation time scale. Droplet coalescence was simulated using a computational framework to validate both experimental approaches. The results indicate that time-dependent monitoring of droplet shape from the EBL intensity allows for robust determination of properties such as surface tension and viscosity. Finally, the potential of high frame rate imaging to examine the coalescence of dissimilar viscosity droplets is discussed.
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Affiliation(s)
- Bryan R Bzdek
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Liam Collard
- Department of Mathematics, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - James E Sprittles
- Mathematics Institute, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Andrew J Hudson
- Department of Chemistry, University of Leicester, Leicester LE1 7RH, United Kingdom
| | - Jonathan P Reid
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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Boyer HC, Bzdek BR, Reid JP, Dutcher CS. Statistical Thermodynamic Model for Surface Tension of Organic and Inorganic Aqueous Mixtures. J Phys Chem A 2016; 121:198-205. [DOI: 10.1021/acs.jpca.6b10057] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hallie C. Boyer
- Department
of Mechanical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455, United States
| | - Bryan R. Bzdek
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Jonathan P. Reid
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Cari S. Dutcher
- Department
of Mechanical Engineering, University of Minnesota, Twin Cities, Minneapolis, Minnesota 55455, United States
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Song YC, Haddrell AE, Bzdek BR, Reid JP, Bannan T, Topping DO, Percival C, Cai C. Measurements and Predictions of Binary Component Aerosol Particle Viscosity. J Phys Chem A 2016; 120:8123-8137. [DOI: 10.1021/acs.jpca.6b07835] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Young Chul Song
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Allen E. Haddrell
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Bryan R. Bzdek
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Jonathan P. Reid
- School
of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - Thomas Bannan
- School
of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - David O. Topping
- School
of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, United Kingdom
- National
Centre for Atmospheric Science, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Carl Percival
- School
of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Chen Cai
- The
Institute of Chemical Physics, Key Laboratory of Cluster Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
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Bzdek BR, Power RM, Simpson SH, Reid JP, Royall CP. Precise, contactless measurements of the surface tension of picolitre aerosol droplets. Chem Sci 2015; 7:274-285. [PMID: 28758004 PMCID: PMC5515047 DOI: 10.1039/c5sc03184b] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/02/2015] [Indexed: 01/25/2023] Open
Abstract
Precise measurements of the surface tension and viscosity of airborne picolitre droplets can be accomplished using holographic optical tweezers.
The surface composition and surface tension of aqueous droplets can influence key aerosol characteristics and processes including the critical supersaturation required for activation to form cloud droplets in the atmosphere. Despite its fundamental importance, surface tension measurements on droplets represent a considerable challenge owing to their small volumes. In this work, we utilize holographic optical tweezers to study the damped surface oscillations of a suspended droplet (<10 μm radius) following the controlled coalescence of a pair of droplets and report the first contactless measurements of the surface tension and viscosity of droplets containing only 1–4 pL of material. An advantage of performing the measurement in aerosol is that supersaturated solute states (common in atmospheric aerosol) may be accessed. For pairs of droplets starting at their equilibrium surface composition, surface tensions and viscosities are consistent with bulk equilibrium values, indicating that droplet surfaces respond to changes in surface area on microsecond timescales and suggesting that equilibrium values can be assumed for growing atmospheric droplets. Furthermore, droplet surfaces are shown to be rapidly modified by trace species thereby altering their surface tension. This equilibration of droplet surface tension to the local environmental conditions is illustrated for unknown contaminants in laboratory air and also for droplets exposed to gas passing through a water–ethanol solution. This approach enables precise measurements of surface tension and viscosity over long time periods, properties that currently are poorly constrained.
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Affiliation(s)
- Bryan R Bzdek
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
| | - Rory M Power
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK . .,Max Planck Institute of Molecular Cell Biology and Genetics , Dresden , 01307 , Germany
| | - Stephen H Simpson
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK . .,Institute of Scientific Instruments of the ASCR. v.v.i. , Krávolopolská 147 , 612 64 , Brno , Czech Republic
| | - Jonathan P Reid
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK .
| | - C Patrick Royall
- School of Chemistry , University of Bristol , Bristol , BS8 1TS , UK . .,H. H. Wills Physics Laboratory , University of Bristol , Bristol , BS8 1TL , UK.,Centre for Nanoscience and Quantum Information , University of Bristol , BS8 1FD , UK
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31
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DePalma JW, Bzdek BR, Ridge DP, Johnston MV. Correction to “Activation Barriers in the Growth of Molecular Clusters Derived From Sulfuric Acid and Ammonia”. J Phys Chem A 2015; 119:931-2. [DOI: 10.1021/acs.jpca.5b00077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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32
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DePalma JW, Bzdek BR, Ridge DP, Johnston MV. Activation Barriers in the Growth of Molecular Clusters Derived from Sulfuric Acid and Ammonia. J Phys Chem A 2014; 118:11547-54. [DOI: 10.1021/jp507769b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joseph W. DePalma
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Bryan R. Bzdek
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Douglas P. Ridge
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Murray V. Johnston
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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33
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Bzdek BR, Horan AJ, Pennington MR, Janechek NJ, Baek J, Stanier CO, Johnston MV. Silicon is a frequent component of atmospheric nanoparticles. Environ Sci Technol 2014; 48:11137-45. [PMID: 25203137 DOI: 10.1021/es5026933] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Nanoparticles are the largest fraction of aerosol loading by number. Knowledge of the chemical components present in nanoparticulate matter is needed to understand nanoparticle health and climatic impacts. In this work, we present field measurements using the Nano Aerosol Mass Spectrometer (NAMS), which provides quantitative elemental composition of nanoparticles around 20 nm diameter. NAMS measurements indicate that the element silicon (Si) is a frequent component of nanoparticles. Nanoparticulate Si is most abundant in locations heavily impacted by anthropogenic activities. Wind direction correlations suggest the sources of Si are diffuse, and diurnal trends suggest nanoparticulate Si may result from photochemical processing of gas phase Si-containing compounds, such as cyclic siloxanes. Atmospheric modeling of oxidized cyclic siloxanes is consistent with a diffuse photochemical source of aerosol Si. More broadly, these observations indicate a previously overlooked anthropogenic source of nanoaerosol mass. Further investigation is needed to fully resolve its atmospheric role.
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Affiliation(s)
- Bryan R Bzdek
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
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Bzdek BR, DePalma JW, Ridge DP, Laskin J, Johnston MV. Fragmentation Energetics of Clusters Relevant to Atmospheric New Particle Formation. J Am Chem Soc 2013; 135:3276-85. [DOI: 10.1021/ja3124509] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Bryan R. Bzdek
- Department of Chemistry and
Biochemistry, University of Delaware, Newark,
Delaware 19716, United States
| | - Joseph W. DePalma
- Department of Chemistry and
Biochemistry, University of Delaware, Newark,
Delaware 19716, United States
| | - Douglas P. Ridge
- Department of Chemistry and
Biochemistry, University of Delaware, Newark,
Delaware 19716, United States
| | - Julia Laskin
- Chemical and Material Sciences
Division, Pacific Northwest National Laboratory, P.O. Box 999, K8-88, Richland, Washington 99352, United States
| | - Murray V. Johnston
- Department of Chemistry and
Biochemistry, University of Delaware, Newark,
Delaware 19716, United States
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35
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Bzdek BR, Horan AJ, Pennington MR, DePalma JW, Zhao J, Jen CN, Hanson DR, Smith JN, McMurry PH, Johnston MV. Quantitative and time-resolved nanoparticle composition measurements during new particle formation. Faraday Discuss 2013; 165:25-43. [DOI: 10.1039/c3fd00039g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bzdek BR, Zordan CA, Pennington MR, Luther GW, Johnston MV. Quantitative assessment of the sulfuric acid contribution to new particle growth. Environ Sci Technol 2012; 46:4365-4373. [PMID: 22435616 DOI: 10.1021/es204556c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Nano Aerosol Mass Spectrometer (NAMS) was deployed to rural/coastal and urban sites to measure the composition of 20-25 nm diameter nanoparticles during new particle formation (NPF). NAMS provides a quantitative measure of the elemental composition of individual, size-selected nanoparticles. In both environments, particles analyzed during NPF were found to be enhanced in elements associated with inorganic species (nitrogen, sulfur) relative to that associated with organic species (carbon). A molecular apportionment algorithm was applied to the elemental data in order to place the elemental composition into a molecular context. These measurements show that sulfate constitutes a substantial fraction of total particle mass in both environments. The contribution of sulfuric acid to new particle growth was quantitatively determined and the gas-phase sulfuric acid concentration required to incorporate the measured sulfate fraction was calculated. The calculated values were compared to those calculated by a sulfuric acid proxy that considers solar radiation and SO(2) levels. The two values agree within experimental uncertainty. Sulfate accounts for 29-46% of the total mass growth of particles. Other species contributing to growth include ammonium, nitrate, and organics. For each location, the relative amounts of these species do not change significantly with growth rate. However, for the coastal location, sulfate contribution increases with increasing temperature whereas nitrate contribution decreases with increasing temperature.
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Affiliation(s)
- Bryan R Bzdek
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, United States
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Pennington MR, Klems JP, Bzdek BR, Johnston MV. Nanoparticle chemical composition and diurnal dependence at the CalNex Los Angeles ground site. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jd017061] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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38
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DePalma JW, Bzdek BR, Doren DJ, Johnston MV. Structure and Energetics of Nanometer Size Clusters of Sulfuric Acid with Ammonia and Dimethylamine. J Phys Chem A 2012; 116:1030-40. [DOI: 10.1021/jp210127w] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joseph W. DePalma
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Bryan R. Bzdek
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Douglas J. Doren
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Murray V. Johnston
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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40
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Affiliation(s)
- Bryan R. Bzdek
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
| | - Douglas P. Ridge
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
| | - Murray V. Johnston
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716
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