Public Health Commons^™

Spatial Hearing In Simulated Reverberant Classroom Environments, Gabriel Seth Evan Weeldreyer

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Spatial hearing provides access to auditory spatial cues that promote speech perception in noisy listening situations. However, reverberation degrades auditory spatial cues and limits listeners’ ability to utilize these cues for segregating target speech from competing babble. Hence, spatial unmasking—an intelligibility benefit from a spatial separation between a target and masker—is reduced in reverberant environments as compared to free field. This work tests the hypothesis that interaural decorrelation, the result of increasing reverberation, will broaden the perceived auditory source width with a cascading effect of reduced auditory spatial acuity and subsequently poorer spatial unmasking. To understand the perceptual consequences of …

Seasonal Comparison Of Air Quality Variables And Evaluation Of Carbon Dioxide And Particulate Measurement Period In Classrooms, Daud Nosham

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Indoor air quality and thermal environmental variables were measured in 55 classrooms in the mid-western United States spanning a full academic year. The studied air quality and environmental factors included carbon dioxide, temperature, relative humidity, particle counts, air velocity, formaldehyde, total volatile organic compounds, carbon monoxide, nitrogen dioxide, and ozone.

Carbon dioxide and Particulate matter concentrations were measured for a four-day measurement period. Then one-day, two-day, and four-day occupied time average concentrations were calculated which were then compared statistically to figure out an appropriate measurement period for these air quality variables. Kruskal Wallis test and Wilcoxon test were used to …

U.S. Army Medical Command’S Medical Treatment Facilities’ Response To Sars-Cov-2 (Covid-19), Seyedmohammad Ahmadshahi

All Theses

Starting in December 2019 to the current time in May 2022, COVID-19 was a devastating pandemic with approximately 440 million cases and 6 million deaths worldwide (Centers for Disease Control and Prevention [CDC], 2021). The United States (US) with roughly 90 million cases and 1 million deaths (CDC, 2021) was one of the epicenters of the outbreak since the beginning. The pandemic has significantly impacted the health systems across the US with unpredictable surges of highly infectious patients with uncertain symptomology and acuity levels, requiring isolation and critical level of care (Brambilla et al., 2021).

Based on the findings from …

Effectiveness Of Building Systems Strategies For Mitigation Of Airborne Transmission Of Sars-Cov-2, Meng Kong, Jialei Shen, Bing Dong, Jianshun Jensen Zhang

Mechanical and Aerospace Engineering - All Scholarship

Airborne transmission has been recognized as a major transmission pathway for the infectious disease COVID-19. This study investigated the effectiveness of several indoor air quality (IAQ) control strategies on the mitigation of airborne transmission of SARS-CoV-2, the virus that causes COVID-19. The well-known airborne disease infection risk model (Wells-Riley equation) was used to estimate the infection risk of the SARS-CoV-2 in seven (7) different types of spaces including conference center/ballrooms, hotel bistro//cafeteria, hotel lobby, classrooms (lecture), conference room/small classroom, hotel or cruise ship guest rooms and open plan offices. The IAQ control strategies included increased ventilation rate, improved air distribution …

Semi Open Partitions: A Defense Strategy For Airborne Disease, Kerrie Marshall, Arik Palileo, Eric A. Schiff

SyracuseCoE Research Brief Series

This brief summarizes research on two measures that reduce the risk of transmitting COVID-19 from an infected person to a virus-free individual. Semi-partitioned spaces can reduce airborne disease transmission when combined with a proper ventilation flow pattern in a room. With advanced displacement ventilation risk can be reduced by at least 4 times.

Student Absenteeism And The Comparisons Of Two Sampling Procedures For Culturable Bioaerosol Measurement In Classrooms With And Without Upper Room Ultraviolet Germicidal Irradiation Devices, Chunxiao Su, Josephine Lau, Shawn G. Gibbs

Durham School of Architectural Engineering and Construction: Faculty Publications

Upper room ultraviolet germicidal irradiance (UVGI) has been shown to reduce the concentration of bioaerosols in controlled chambers. However, there is a lack of experimental results on the reduction of bioaerosol concentrations by UVGI devices in actual uncontrolled buildings. This study was carried out in an American elementary school in the Midwest. Two sampling procedures were carried out in six selected classrooms with similar dimensions that were separated into two groups: (1) UVGI exposure group and (2) non-UVGI control group. Two-stage Tisch culturable impactors were utilized to collect airborne culturable bacteria and fungi. Monthly samples were collected during unoccupied period …

Experimental Validation Of The Multiple-Zone System Ventilation Efficiency Equation Of Ansi/Ashrae Standard 62.1 (1276-Rp), David P. Yuill, Grenville K. Yuill, Andrew H. Coward

David Yuill

This article describes an experiment that was carried out on an existing building to test the validity of the system ventilation efficiency equation for multiple-zone recirculating systems of ANSI/ASHRAE Standard 62.1. The system ventilation efficiency equation (SVEE) can be applied to buildings that use a recirculating air distribution system. It accounts for the fact that the return air carries some “unused” outdoor air, so that the amount of new outdoor air introduced at the air handler can be reduced. The SVEE is based on a mass balance but infiltration and interzonal mixing are not included in the formulation. Since infiltration …

Development Of A Novel Methodology For Indoor Emission Source Identification, Kwanghoon Han

Kwanghoon Han

The objective of this study was to develop and evaluate a methodology to identify individual sources of emissions based on the measurements of mixed air samples and the emission signatures of individual materials previously determined by Proton Transfer Reaction-Mass Spectrometry (PTR-MS), an on-line analytical device. The methodology based on signal processing principles was developed by employing the method of multiple regression least squares (MRLS) and a normalization technique. Samples of nine typical building materials were tested individually and in combination, including carpet, ceiling material, gypsum board, linoleum, two paints, polyolefine, PVC and wood. Volatile Organic Compound (VOC) emissions from each …

Determination Of Material Emission Signatures By Ptr-Ms And Their Correlations With Odor Assessments By Human Subjects, Kwanghoon Han

Kwanghoon Han

The objectives of this study were to determine volatile organic compound (VOC) emission signatures of nine typical building materials by using proton transfer reaction-mass spectrometry (PTR-MS) and to explore the correlation between the PTR-MS measurements and the measurements of acceptability by human subjects. VOC emissions from each material were measured in a 50-l small-scale chamber. Chamber air was sampled by PTR-MS to determine emission signatures. Sorbent tube sampling and TD-GC/MS analysis were also performed to identify the major VOCs emitted and to compare the resulting data with the PTR-MS emission signatures. The data on the acceptability of air quality assessed …