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In this study, Three-dimensional (3D) airflow and dispersion of pollutants were modeled under various excess wall temperature and traffic rate using the RNG k-£` turbulence model and Boussinesq approximation, which was solved numerically using the finite volume method. The street canyon is 60 m long (=L) and 20 m wide (=W). The height of five-story buildings on both sides of the street are about 16 m (=H). Hence, the street canyon has an aspect ratio (AR=H/W) of 0.8 and a length to width ratio of 3 (=L/W). Vehicle emissions were estimated from the measured traffic flow rates and modeled as banded line sources. 3D simulations reveal that the vortex line, joining the centers of cross-sectional vortices of the street canyon, meanders between street buildings. Notably, there is also a horizontal vortex within street canyon. Pollutant concentrations decline as the height increases, and are higher on the leeward side than on the windward side. The ratio of CO pollutants between leeward side and windward side is related to wind velocity. As wind smaller than 0.7 m/sec , the ratio is 1.23¡Fhowever, the ratio is 2.03 with more wind speed above 1.2 m/sec. The CO concentration reveals that the predicted values generally follow the hourly zigzag traffic rate, indicating that CO is closely related to the traffic emissions in a street canyon. The 3D airflow in the street canyon is dominated by both wind fields on buildings top and street exit. The 3D simulations reveal that air flux is 50% higher than 2D. Entrainment of outside air reduces pollutant concentrations, thus reducing concentrations of CO¡BNOx¡Band SO2 by about 51%¡B68% and 70% ,respectively. Thermal boundary layers are very thin. Entrainment of outside air increases and pollutant concentration decreases with increasing heating condition. For T = 5 K, the upward velocity on leeward side increases by about 10%, Also, the downward velocity on windward side decreases by about 28 %. Furthermore, simulation showed that the averaged inflow speed in the lateral direction increases by about 100% as compared with T = 0 K. Hence, the pollutant concentrations with T = 5 K is ony 50% of those without heating. Simulations are followed measurements in street canyon. The averaged simulated concentrations with no heating conditions are about 11~24% and 22~36% lower than measured for CO and NOx , respectively. For heating conditions and without outside traffic source, the averaged simulated concentrations with T = 2 K are 29~36% lower than the measurements. Even at T = 5 K , the concentrations are only about 54% of those without heating, due to the fact that pollutant dilution is enhanced by buoyancy force as to having more outside air entrained into the canyon. However, when traffic emissions outside two ends of canyon were considered, the simulated CO concentrations are 23% and 19% higher than those without outside traffic sources at T = 0 K and T = 2 K, respectively. Traffic-produced turbulence (TPT) enhances the turbulent kinetic energy and the mixing of temperature and admixtures in the canyon. Although the simulated means with the TPT effect are in better agreement with the measured means than those without the TPT effect, the average reduction of CO concentration by the TPT is only about 5% at a given height and heating conditions. Factors affecting the variations between this work and other studies are addressed and explained.

The western part of the border between Mexico and the United States consists of two primary regions, Tijuana-San Diego and Mexicali-Calexico (Imperial Valley). Over the last fifteen years Mexicali has been one of the fastest-growing cities in Mexico in terms of industrial development, job creation, and energy demand, thus resulting in increased air pollution and environmental degradation. This air pollution has thus been linked to high rates of asthma and respiratory diseases on both sides of the border. This thesis focuses on pollutant formation and pollutant interactions between the three regions of the Mexicali-Imperial Valley (MC), Tijuana-San Diego (TS), and Los Angeles (LA) areas. The MODELS-3 modeling approach is used for analyzing the formation of secondary species, and transport of both primary and secondary pollutants between the regions during three pollution episodes in July 2001, August 2001, and January 2002. Area and mobile sources are identified as primary pollutant emitters in MC and TS regions. Source contribution from within the region and from other regions is conducted using CMAQ/ DDM. During the summer episode, O3 plumes originating from TS are transported eastwards along the border region towards MC. O3 plumes generated from precursors emitted by LA mobile sources are transported towards MC and add up to 10 ppbv in the MC region. O3 plumes reach the border regions of California-Arizona and O3 concentrations up to 4 ppbv in the Grand Canyon area can be attributed to area sources in the MC region. Contribution of up to 11 ppbv of O3 in Calexico-Mexicali can be attributed to the high density of vehicles in and around the San Diego region. During the winter episode, the winds being southeasterly (towards southeast) plumes from TS, LA and Las Vegas unite and move towards the MC region with impacts of 10-35 μg m-3. The soil dust contributions from LA, TS and MC range between 5-25 μg m-3. MC area sources contribute a maximum of 34 μg m-3 PM2.5.

Air emissions from animal feeding operations have become a growing concern. Much work has been done to study occupational exposures and the exhaust concentrations associated with animal facilities; however little information has been provided about air quality around the houses. Ammonia (NH3 ), ethanol (EtOH), nitrous oxide (N2O), carbon dioxide (CO2), and particulate matter (PM 2.5 and PM10) emissions were monitored in two different buildings for laying hens in northern Utah. Over the six-month sampling period, the observed average temperatures for the west and east fan banks of the high-rise building were 21.2±4 and 19.4±1.3°C, respectively, and the average inside relative humidities during the same period were 43.7±7.2 and 48.4±7.9%, respectively. Furthermore, the observed average temperatures for the west and east fan banks of the manure-belt building were 20.6±4.4 and 17.9±2.7°C, respectively, and the average percent inside relative humidities during the same period were 44.4 ±7.6 and 49.3±7.4%, respectively. The ventilation rates ranged from 0.80 m3 h-1 bird-1 to 4.80 m3 h-1 bird -1 with an average of 2.02 m3 h -1 bird -1 for the high-rise barn and from 0.80 m3 h-1 bird -1 to 6.0 m3 h-1 bird-1 with an average of 2.20 m3 h-1 bird-1 for the manure-belt building over the sampling period of September, October, November, and December 2008 and January 2009. Average NH3 emission factors were 72±17 g d-1 AU-1 for the high-rise system and 9.1±7 g d-1 AU-1 for the manure-belt (1 AU is equal to 500 kg of animal live weight). The NH3 emission reduction factor for the manure-belt technique compared to the high-rise technique was 87%. Ammonia levels outside the house appeared to be less than 1 ppm. No significant emissions were registered for N2O, H2S, and EtOH, which were consistently close to zero for both techniques. The carbon dioxide (CO2) emission factor from the high-rise building was 104±11 g day-1 AU-1 and from the manure-belt building, 105±20 g day-1 AU-1. PM emissions were greater from the manure-belt system in comparison with the high-rise system, showing mean values of 165 vs. 114 g day-1 AU-1 for PM 2.5, 1,987 vs. 1,863 g day-1 AU-1for PM10 and 4,460 vs. 3,462 g day-1 AU-1 for TSP respectively. None of the 24-h PM 2.5 measurements collected from both management techniques exceeded the U.S. EPA 24-hr National Ambient Air Quality Standard (NAAQS) of 35 μg/m 3.

<p>Indoor air quality in office buildings can impact the health, well-being, and productivity of occupants. In most buildings, occupants exhaled breath is the primary source of carbon dioxide (CO₂). Concentrations of indoor CO₂ are also strongly associated with the operational mode of the mechanical ventilation system. While CO2 is routinely monitored in indoor environments, there are few spatially-resolved real-time measurements of CO₂ throughout mechanical ventilation systems. Such measurements can provide insight into indoor- and outdoor-generated CO₂ dispersion throughout a building and between the building and the outdoor atmosphere. This thesis aims to investigate spatiotemporal variations in CO₂ concentrations and mass fluxes throughout a mechanical ventilation system of a living laboratory office in a LEED-certified building. The impact of human occupancy patterns and ventilation conditions of CO₂ concentrations and fluxes was evaluated. </p> <p>A four-month measurement campaign was conducted in one of the four living laboratory offices at the Ray W. Herrick Laboratories. The living laboratory offices feature precise control and monitoring of the mechanical ventilation system via an advanced building automation system. Various mechanical ventilation modes were implemented, such as variable outdoor air exchange rates (AERs) and recirculation ratios. A novel multi-location sampling manifold was used to measure CO₂ at eight locations throughout the ventilation system, such as across the outdoor, supply, and return air ducts. Office occupancy was measured via a chair-based temperature sensor array. Volumetric airflow rate data and CO₂ concentration data were used to estimate CO₂ mass fluxes through the ventilation system. The CO₂ mass flux for the outdoor and exhaust air was used to evaluate the net CO₂ transport from the office to the outdoor atmosphere. </p> <p>The measurements demonstrate that there exist significant spatiotemporal variations in CO₂ concentrations across the outdoor, supply, and return air ducts. CO₂ concentrations varied with human occupancy in the office and the outdoor AER of the mechanical ventilation system. Due to human-associated CO₂ emissions, the net CO₂ mass flux from the office to the outdoor environment was approximately 700 kg of CO₂ per year. Thus, occupied offices may represent an important, yet unrecognized, source of CO₂ to the urban atmosphere.</p>

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Doctor of Philosophy / Department of Chemistry / Kenneth J. Klabunde / Solar energy driven catalytic systems have gained popularity in environmental remediation recently. Various photocatalytic systems have been reported in this regard and most of the photocatalysts are based on well-known semiconducting material, Titanium Dioxide, while some are based on other materials such as Silicon Dioxide and various Zeolites. However, in titania based photocatalysts, titania is actively involved in the catalytic mechanism by absorbing light and generating exitons. Because of this vast popularity of titania in the field of photocatalysis it is believed that photocatalysis mainly occurs via non-localized mechanisms and semiconductors are extremely important. Even though it is still rare, photocatalysis could be localized and possible without use of a semiconductor as well. Thus, to support localized photocatalytic systems, and to compare the activity to titania based systems, degradation of organic air pollutants by nanostructured silica, titania and mixed silica titania systems were studied. New materials were prepared using two different approaches, precipitation technique (xerogel) and aerogel preparation technique. The prepared xerogel samples were doped with both metal (silver) and non-metals (carbon and sulfur) and aerogel samples were loaded with Chromium, Cobalt and Vanadium separately, in order to achieve visible light photocatalytic activity. Characterization studies of the materials were carried out using Nova BET analysis, DR UV-vis spectrometry, powder X-ray diffraction, X-ray photoelectron Spectroscopy, FT-IR spectroscopy, Transmission Electron Microscopy, etc. Kinetics of the catalytic activities was studied using a Shimadzu GCMS-QP 5000 instrument using a closed glass reactor. All the experiments were carried out in gaseous phase using acetaldehyde as the model pollutant. Kinetic results suggest that chromium doped silica systems are good UV and visible light active photocatalysts. This is a good example for a localized photocatalytic activity. In contrast, our xerogel system shows comparatively high visible light photocatalytic activity for the titania based system, showing the importance of non-localized nature of photocatalysis. The Cobalt doped silica system shows interesting dark catalytic activity towards acetaldehyde and several other pollutants. Thus, in summary, based on the different activities we observed during our studies these materials could be successfully used to improve the quality of both indoor and outdoor air.

A Lagrangian particle model was applied to estimating emission strength and air pollutant concentrations specifically for the short-range dispersion of an air pollutant in the atmospheric boundary layer. The model performance was evaluated with experimental data. The model was then used as the platform of parametric uncertainty analysis, in which effects of uncertainties in five parameters (Monin-Obukhov length, friction velocity, roughness height, mixing height, and the universal constant of the random component) of the model on mean ground-level concentrations were examined under slightly and moderately stable conditions. The analysis was performed under a probabilistic framework using Monte Carlo simulations with Latin hypercube sampling and linear regression modeling. In addition, four studies related to the Lagrangian particle modeling was included. They are an alternative technique of formulating joint probability density functions of velocity for atmospheric turbulence based on the Koehler-Symanowski technique, analysis of local increments in a multidimensional single-particle Lagrangian particle model using the algebra of Ito integrals and the Wagner-Platen formula, analogy between the diffusion limit of Lagrangian particle models and the classical theory of turbulent diffusion, and evaluation of some proposed forms of the Lagrangian velocity autocorrelation of turbulence.

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