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Glenn K, He J, Rochlin R, Teng S, Hecker JG, Novosselov I. Assessment of aerosol persistence in ICUs via low-cost sensor network and zonal models. Sci Rep 2023; 13:3992. [PMID: 36899063 PMCID: PMC10006437 DOI: 10.1038/s41598-023-30778-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 03/01/2023] [Indexed: 03/12/2023] Open
Abstract
The COVID-19 pandemic raised public awareness about airborne particulate matter (PM) due to the spread of infectious diseases via the respiratory route. The persistence of potentially infectious aerosols in public spaces and the spread of nosocomial infections in medical settings deserve careful investigation; however, a systematic approach characterizing the fate of aerosols in clinical environments has not been reported. This paper presents a methodology for mapping aerosol propagation using a low-cost PM sensor network in ICU and adjacent environments and the subsequent development of the data-driven zonal model. Mimicking aerosol generation by a patient, we generated trace NaCl aerosols and monitored their propagation in the environment. In positive (closed door) and neutral-pressure (open door) ICUs, up to 6% or 19%, respectively, of all PM escaped through the door gaps; however, the outside sensors did not register an aerosol spike in negative-pressure ICUs. The K-means clustering analysis of temporospatial aerosol concentration data suggests that ICU can be represented by three distinct zones: (1) near the aerosol source, (2) room periphery, and (3) outside the room. The data suggests two-phase plume behavior: dispersion of the original aerosol spike throughout the room, followed by an evacuation phase where "well-mixed" aerosol concentration decayed uniformly. Decay rates were calculated for positive, neutral, and negative pressure operations, with negative-pressure rooms clearing out nearly twice as fast. These decay trends closely followed the air exchange rates. This research demonstrates the methodology for aerosol monitoring in medical settings. This study is limited by a relatively small data set and is specific to single-occupancy ICU rooms. Future work needs to evaluate medical settings with high risks of infectious disease transmission.
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Affiliation(s)
- K Glenn
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - J He
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - R Rochlin
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - S Teng
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - J G Hecker
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, USA
| | - I Novosselov
- Department of Mechanical Engineering, University of Washington, Seattle, USA.
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Lee UN, van Neel TL, Lim FY, Khor JW, He J, Vaddi RS, Ong AQW, Tang A, Berthier J, Meschke JS, Novosselov IV, Theberge AB, Berthier E. Miniaturizing Wet Scrubbers for Aerosolized Droplet Capture. Anal Chem 2021; 93:11433-11441. [PMID: 34379402 DOI: 10.1021/acs.analchem.1c01296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aerosols dispersed and transmitted through the air (e.g., particulate matter pollution and bioaerosols) are ubiquitous and one of the leading causes of adverse health effects and disease transmission. A variety of sampling methods (e.g., filters, cyclones, and impactors) have been developed to assess personal exposures. However, a gap still remains in the accessibility and ease-of-use of these technologies for people without experience or training in collecting airborne samples. Additionally, wet scrubbers (large non-portable industrial systems) utilize liquid sprays to remove aerosols from the air; the goal is to "scrub" (i.e., clean) the exhaust of industrial smokestacks, not collect the aerosols for analysis. Inspired by wet scrubbers, we developed a device fundamentally different from existing portable air samplers by using aerosolized microdroplets to capture aerosols in personal spaces (e.g., homes, offices, and schools). Our aerosol-sampling device is the size of a small teapot, can be operated without specialized training, and features a winding flow path in a supersaturated relative humidity environment, enabling droplet growth. The integrated open mesofluidic channels shuttle coalesced droplets to a collection chamber for subsequent sample analysis. Here, we present the experimental demonstration of aerosol capture in water droplets. An iterative study optimized the non-linear flow manipulating baffles and enabled an 83% retention of the aerosolized microdroplets in the confined volume of our device. As a proof-of-concept for aerosol capture into a liquid medium, 0.5-3 μm model particles were used to evaluate aerosol capture efficiency. Finally, we demonstrate that the device can capture and keep a bioaerosol (bacteriophage MS2) viable for downstream analysis.
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Affiliation(s)
- Ulri N Lee
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - Tammi L van Neel
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - Fang Yun Lim
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - Jian Wei Khor
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - Jiayang He
- Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Ravi S Vaddi
- Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Angelo Q W Ong
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, Washington 98105, United States
| | - Anthony Tang
- Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, United States
| | - Jean Berthier
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
| | - John S Meschke
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, Washington 98105, United States
| | - Igor V Novosselov
- Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195, United States.,Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, Washington 98105, United States.,Institute of Nano-Engineering Sciences, University of Washington, Box 351654, Seattle, Washington 98195, United States
| | - Ashleigh B Theberge
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States.,Department of Urology, University of Washington School of Medicine, Seattle, Washington 98195, United States
| | - Erwin Berthier
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States
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Mahamuni G, He J, Rutherford J, Ockerman B, Majumdar A, Seto E, Korshin G, Novosselov I. Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols. PLoS One 2021; 16:e0251664. [PMID: 34014964 PMCID: PMC8136721 DOI: 10.1371/journal.pone.0251664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 04/30/2021] [Indexed: 12/01/2022] Open
Abstract
Exposure to ultrafine combustion aerosols such as particulate matter (PM) from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. Excitation-emission matrix (EEM) spectroscopy presents a sensitive and cost-effective alternative for analysis of PM organic fraction. However, as with other analytical chemistry methods, the miniaturization is hindered by a solvent extraction step and a need for benchtop instrumentation. We present a methodology for collecting and in-situ analysis of airborne nanoparticles that eliminates labor-intensive sample preparation and miniaturizes the detection platform. Nanoparticles are electrostatically collected onto a transparent substrate coated with solid-phase (SP) solvent-polydimethylsiloxane (PDMS). The PM organic fraction is extracted into PDMS and analyzed in-situ, thus avoiding liquid-phase extraction. In the SP-EEM analysis, we evaluated external and internal excitation schemes. Internal excitation shows the lowest scattering interference but leads to signal masking from PDMS fluorescence for λ<250nm. The external excitation EEM spectra are dependent on the excitation light incident angle; ranges of 30-40° and 55-65° show the best results. SP-EEM spectra of woodsmoke and cigarette smoke samples are in good agreement with the EEM spectra of liquid-phase extracts. The SP-EEM technique can be used to develop wearable sensors for exposure assessments and environmental monitoring.
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Affiliation(s)
- Gaurav Mahamuni
- University of Washington, Mechanical Engineering, Seattle, WA, United States of America
| | - Jiayang He
- University of Washington, Mechanical Engineering, Seattle, WA, United States of America
| | - Jay Rutherford
- University of Washington, Chemical Engineering, Seattle, WA United States of America
| | - Byron Ockerman
- University of Washington, Mechanical Engineering, Seattle, WA, United States of America
| | - Arka Majumdar
- University of Washington, Electrical and Computer Engineering, Seattle, WA United States of America
| | - Edmund Seto
- University of Washington, Environmental and Occupational Health Sciences, Seattle, WA United States of America
| | - Gregory Korshin
- University of Washington, Civil and Environmental Engineering, Seattle, WA United States of America
| | - Igor Novosselov
- University of Washington, Mechanical Engineering, Seattle, WA, United States of America
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Vaddi RS, Guan Y, Novosselov I. Behavior of Ultrafine Particles in Electro-Hydrodynamic Flow Induced by Corona Discharge. JOURNAL OF AEROSOL SCIENCE 2020; 148:105587. [PMID: 32704186 PMCID: PMC7377583 DOI: 10.1016/j.jaerosci.2020.105587] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Ultrafine particle behavior in electro-hydrodynamic (EHD) flow induced by corona discharge is studied experimentally and numerically. The EHD flow serves as a primary particle aspiration/sampling mechanism, the collector does not require any additional flow generation. Multiphysics numerical model couples the ion transport equation and the Navier-Stokes equations (NSE) to solve for the spatiotemporal distribution of electric field, charge density, and flow field, the results are compared with experimental velocity profiles at the exit. The computed velocity and flow rate data are in good agreement with the experimental data; the maximum velocity is located at the axis and ranges from 1 m/s to 4 m/s as a function of corona voltage. Experimentally evaluated particle transmission trends for ambient and NaCl nanoparticles particles in the 20 nm - 150 nm range are in good agreement with the theoretical models. However, for particles in the 10 nm - 20 nm size range, the transmission is lower due to the increased particle charging resulted from their exposure to the high-intensity electric field and high charge density in the EHD driven flow. These conditions yield a high probability of particles below 20 nm to acquire and hold a unit charge. The transmission is lower for smaller particle (10 nm) due to their high charge to mass ratio, and it increases as the single-charged particles grow in mass up to 20 nm, resulting in their lower electrical mobility. For particles larger than 20 nm, the electrical mobility increases again as they can acquire multiple charges. The results shed insight into interaction of nanoparticle and ions in high electrical field environment, that occur in primary EHD driven flows and in the secondary flows generated by corona discharge.
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Affiliation(s)
- Ravi Sankar Vaddi
- Department of Mechanical Engineering, University of Washington, Seattle, USA
| | - Yifei Guan
- Department of Mechanical Engineering, Rice University, Houston, U.S.A.77005
| | - Igor Novosselov
- Department of Mechanical Engineering, University of Washington, Seattle, USA
- Institute of Nano-Engineered Systems, University of Washington, Seattle
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Duncan GE, Seto E, Avery AR, Oie M, Carvlin G, Austin E, Shirai JH, He J, Ockerman B, Novosselov I. Usability of a Personal Air Pollution Monitor: Design-Feedback Iterative Cycle Study. JMIR Mhealth Uhealth 2018; 6:e12023. [PMID: 30578204 PMCID: PMC6320397 DOI: 10.2196/12023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/10/2018] [Accepted: 10/13/2018] [Indexed: 11/13/2022] Open
Abstract
Background There is considerable evidence that exposure to fine particulate matter (PM2.5) air pollution is associated with a variety of adverse health outcomes. However, true exposure-outcome associations are hampered by measurement issues, including compliance and exposure misclassification. Objective This paper describes the use of the design-feedback iterative cycle to improve the design and usability of a new portable PM2.5 monitor for use in an epidemiologic study of personal air pollution measures. Methods In total, 10 adults carried on their person a prefabricated PM2.5 monitor for 1 week over 3 waves of the iterative cycle. At the end of each wave, they participated in a 30-minute moderated focus group and completed 2 validated questionnaires on usability and views on research. The topics addressed included positives and negatives of the monitor, charging and battery life, desired features, and changes to the monitor from each previous wave. They also completed a log to record device wear time each day. The log also provided space to record any issues that may have arisen with the device or for general comments during the week of collection. Results The major focus group topics included device size, noise, battery and charge time, and method for carrying the device. These topics formed the basis of iterative design changes; by the final cycle, the device was reasonably smaller, quieter, held a longer charge, and was more convenient to carry. System usability scores improved systematically across each wave (median scores of 50-66 on a 100-point scale), as did median daily wear time (approximately 749-789 minutes). Conclusions Both qualitative and quantitative measures showed an improvement in device usability over the 3 waves. This study demonstrates how the design-feedback iterative cycle can be used to improve the usability of devices manufactured for use in large epidemiologic studies on personal air pollution exposures.
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Affiliation(s)
- Glen E Duncan
- Washington State University, Spokane, WA, United States
| | - Edmund Seto
- University of Washington, Seattle, WA, United States
| | - Ally R Avery
- Washington State University, Everett, WA, United States
| | - Mike Oie
- Washington State University, Seattle, WA, United States
| | | | - Elena Austin
- University of Washington, Seattle, WA, United States
| | | | - Jiayang He
- University of Washington, Seattle, WA, United States
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