Publications by authors named "Darrah K Sleeth"

Healthcare personnels (HCPs) are at risk of respiratory infectious diseases during patient care activities. HCPs rely primarily on personal protective equipment to prevent pathogen exposures, but there is a need to develop alternative, or complementary control strategies, including engineering controls. The objective of this study was to evaluate the ability of the 3 designs (denoted D1A, D1B, and D2) of the University of Utah Containment Ventilation for Exposure Reduction (U-COVER), a protective barrier enclosure device to contain respirable aerosols when placed over a simulated patient.

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Increasing concern over air pollution has led to the development of low-cost sensors suitable for wide-scale deployment and use by citizen scientists. This project investigated the AirU low-cost particle sensor using two methods: (1) a comparison of pre- and post-deployment calibration equations for 24 devices following use in a field study, and (2) an in-home comparison between 3 AirUs and a reference instrument, the GRIMM 1.109.

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Health care workers (HCWs) can acquire infectious diseases, including coronavirus disease 2019 (COVID-19), from patients. Herein, COVID-19 is used with the source-pathway-receptor framework as an example to assess evidence for the roles of aerosol transmission and indirect contact transmission in viral respiratory infectious diseases. Evidence for both routes is strong for COVID-19 and other respiratory viruses, but aerosol transmission is likely dominant for COVID-19.

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The objective of this study was to determine the influence of face shields on the concentration of respirable aerosols in the breathing zone of the wearer. The experimental approach involved the generation of poly-dispersed respirable test dust aerosol in a low-speed wind tunnel over 15 min, with a downstream breathing mannequin. Aerosol concentrations were measured in the breathing zone of the mannequin and at an upstream location using two laser spectrophotometers that measured particle number concentration over the range 0.

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A scoping review was performed to answer: what environmental health concerns have been associated with adverse health outcomes in the Navajo Nation? The review focused on occupational and ambient environmental exposures associated with human industrial activities. The search strategy was implemented in PubMed, and two investigators screened the retrieved literature. Thirteen studies were included for review.

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Native American populations face considerable health disparities, especially among those who live on reservations, where access to healthcare, education, and safe housing can be limited. Previous research on tribal housing has raised concerns about housing construction, damage, and possible linkage to adverse health effects (e.g.

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Based on experiments conducted in low wind speed and calm air environments, the current International Organization for Standardization (ISO) and European Committee for Standardization (CEN) convention modeling human aerosol inhalability (i.e. aspiration efficiency) may not be valid when wind speeds are less than 0.

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An ideal inhalable aerosol sampler for occupational exposure monitoring would have a sampling efficiency that perfectly matches the inhalable particulate matter (IPM) criterion. Two common aerosol samplers in use worldwide are the closed-face cassette (CFC) and the Institute of Occupational Medicine (IOM) sampler. However, the CFC is known to under-sample, with near zero sampling efficiency for particles >30 µm, whereas the IOM, considered by many to be the "gold standard" in inhalable samplers, has been shown to over-sample particles >60 µm.

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Exposure to occupational aerosols are a known hazard in many industry sectors and can be a risk factor for several respiratory diseases. In this study, a laboratory evaluation of low-cost aerosol sensors, the Dylos DC1700 and a modified Dylos known as the Utah Modified Dylos Sensor (UMDS), was performed to assess the sensors' efficiency in sampling respirable and inhalable dust at high concentrations, which are most common in occupational settings. Dust concentrations were measured in a low-speed wind tunnel with 3 UMDSs, collocated with an aerosol spectrometer (Grimm 1.

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A newly designed, low-cost, disposable inhalable aerosol sampler was developed to assess workers personal exposure to inhalable particles. This sampler was originally designed to operate at 10 L/min to increase sample mass and, therefore, improve analytical detection limits for filter-based methods. Computational fluid dynamics modeling revealed that sampler performance (relative to aerosol inhalability criteria) would not differ substantially at sampler flows of 2 and 10 L/min.

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Article Synopsis
  • Extrathoracic deposition of inhaled particles is a significant exposure pathway for hazardous materials, particularly in the head and throat areas.
  • New ISO standards (ISO 13138) focus on sampling conventions for measuring how particles deposit in the upper respiratory tract, specifically the anterior and posterior nasal passages.
  • This study tested polyurethane foam in an aerosol sampler, finding that it effectively estimates extrathoracic particle deposition for various sizes of aluminum oxide aerosols using a rotating mannequin setup in a wind tunnel.
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Article Synopsis
  • The text discusses the importance of where inhaled particles deposit in the body, leading to the adoption of a particle deposition sampling convention by the International Organization for Standardization.
  • A study was conducted to evaluate how well a polyurethane foam insert in an IOM sampler mimicked this convention by testing different particle sizes and accounting for static electricity.
  • Results showed that while the foam insert generally matched the sampling convention for larger particles, it underestimated efficiencies for all sizes, with a significant difference noted only for the smallest particle size when comparing standard and neutralized particles.
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Article Synopsis
  • The research investigated the effectiveness of the 37-mm closed-face cassette (CFC) sampler for aerosol collection by comparing two orientations: the traditional 45° angle and a proposed horizontal 0° angle.
  • Conducted in a wind tunnel with fused alumina oxide particles of varying sizes, the study included 12 sampling events, collecting a total of 94 samples to compare mass concentration measurements.
  • Results showed no significant differences in aerosol measurements between the two orientations, and less than 5% of the mass was lost on the cassette walls, suggesting that both methods are similar in effectiveness for sampling.
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In 2010, the American Conference of Governmental Industrial Hygienists (ACGIH) formally changed its Threshold Limit Value (TLV) for beryllium from a 'total' particulate sample to an inhalable particulate sample. This change may have important implications for workplace air sampling of beryllium. A history of particle size-selective sampling methods, with a special focus on beryllium, will be provided.

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This study analyzed data from the Occupational Safety and Health Administration's (OSHA) Chemical Exposure Health Database to assess contaminant exposures in general medical and surgical hospitals. Seventy-five inspections conducted in these hospitals from 2005 through 2009 were identified. Five categories of inspections were conducted, the three most common being complaint-based, planned, and referral-based inspections.

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Air samples were collected in 12 randomly selected commercial nail salons in Salt Lake County, Utah. Measurements of salon physical/chemical parameters (room volume, CO2 levels) were obtained. Volatile organic compound (VOC) concentrations were collected using summa air canisters and sorbent media tubes for an 8-h period.

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The assessment of personal inhalable aerosol samplers in a controlled laboratory setting has not previously been carried out at the ultra-low wind speed conditions that represent most modern workplaces. There is currently some concern about whether the existing inhalable aerosol convention is appropriate at these low wind speeds and an alternative has been suggested. It was therefore important to assess the performance of the most common personal samplers used to collect the inhalable aerosol fraction, especially those that were designed to match the original curve.

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The current convention for sampling inhalable aerosols was based on several mannequin studies performed in wind tunnels at wind speeds between 0.5 and 4 m s(-1). In reality, as we now know, the wind speed in most modern indoor working environments is generally at or below ∼0.

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