The purpose of this study was to investigate whether or not differing base metals and filler wires used during welding processes contributed to differing amounts of ultrafine particles (UFP) and nanoparticles being emitted during the welding procedure. The study was also conducted to determine UFP and nanoparticle exposure in the breathing zones of the welders as well as the breathing zones of pipefitters and fire watchers, who commonly sit 6ft behind the welding arc. In order to determine if UFP and NP exposures differed with base metal and filler wire, all welding processes utilized the same welding machine for metal inert gas (MIG), the same wire speed, and the same voltages during each welding process. The only variation in welding procedures were cover gases used, base metals, and filler wires. Measurements gathered during welding procedures were conducted in the breathing zone of the welder and pipefitters consisted of UFP measurements taken by two different condensation particle counters (CPC), which operated in synchrony at the start and cessation of the welding process. NP measurements were taken by a NanoScan Scanning Mobility Particle Sizer (SMPS) and were also placed in the breathing zone of the welder. Lastly, particle characterization measurements for transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) were gathered using a filter attached to a high flow pump, which was placed in the breathing zone of the welder. According to the results, base metal and filler wire do emit differing amounts of NP and UFP during the welding processes. Carbon steel emits the highest amount of nanoparticles, while stainless steel emits the second highest amount, and inconel emits the least. The results also concluded that welders are exposed to a greater concentration of nanoparticles and UFPs than those experienced by pipefitters who stand 6ft from the welding arc.

Chlorpyrifos (CPF) is a popular organophosphorus insecticide that is heavily used in the agriculture industry as a means of pest control. Chlorpyrifos is known for its toxic effect to inhibit the enzyme acetylcholinesterase (ACHE) in humans and is widely used in areas of California where the site of application is close to occupied areas, such that exposures to residents and bystanders can occur due to secondary drift. Secondary drift refers to the volatilization of a pesticide from the surface to which it was applied (e.g. soil or plant foliage) and subsequent off-site movement in ambient air. Secondary drift is different from spray drift, which occurs during and very shortly after application. The goal of this thesis is to evaluate existing measurements of secondary drift from ambient air measurements of CPF available from California’s Air Monitoring Network (AMN), in comparison to predictions using a state-of-the-art dispersion model. Pesticide use data were obtained from the California Department of Pesticide Regulation (CDPR) website and was compiled to form scenarios to be modeled and compared against measurements taken throughout the year. Probability distributions for the measured and predicted CPF concentrations resulted in correlations ranging from 3% to 91% depending on the year and modeled scenario. Overall the model overpredicted air concentrations for the modeled scenarios, providing conservative values for risk assessment purposes.

Workers are exposed to stressful thermal work environments in multiple industries every day. Methods for assessing heat stress often struggle to balance productivity without compromising the health of the workers. The Thermal Work Limit (TWL) is a method that has been adopted in areas outside of the United States as a viable method for heat assessment that combines health with productivity. TWL recommends a maximum metabolic rate for a given set of environmental conditions, clothing ensemble and acclimatization state. The purpose of this paper was to evaluate the validity of the TWL against a set of heat stress data known to be at the maximum sustainable level. A range of conditions were combined through environmental (20%, 50% and 70% relative humidity), clothing (woven clothing, WC; particle barrier coveralls, PB; water barrier coveralls, WB; and vapor barrier coveralls, VB), and workload factors (metabolic rates at low, L; moderate, M; and high, H) at the transition from sustainable to unsustainable exposure to ensure that the TWL method is thoroughly explored. Data from previous heat stress studies were used to compare the difference in predicted TWL with a calculated value. An analysis of variance (ANOVA) demonstrated that there were significant effects of the TWL due to clothing, metabolic rate level and relative humidity level. TWL provided similar results for WC, PB and WB, but had systematically lower values for VB. This suggested a more protective recommendation with high evaporative resistance. As the metabolic rate increased, the recommended limiting TWL also went up out of proportion to the metabolic rate, which provided greater protection at increasing metabolic rates. Under drier conditions (20% relative humidity), the TWL was systematically lower than for 50% and 70% relative humidity. While there were significant differences due to the main effects, the TWL was designed to be used without defined limits on environmental conditions, metabolic rate or clothing. Therefore, all of the conditions represented a comprehensive test of the TWL. Overall, the TWL was less protective than the current methods used by ACGIH Threshold Limit Values (TLV) and National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL). At the threshold, the TWL had a 7% probability of being unsustainable compared to the threshold probability of 1% for the TLV and REL.

Understanding the relationships between human health, water, sanitation, and environmental health is a requirement to understanding the challenges that face researchers when it comes to addressing global health relating to water and sanitation. Access to improved water and sanitation is not only a precondition to health, but to all aspects of daily living. Target 7.C of the Millennium Development Goals (MDGs) addresses worldwide disparities in access to improved water and sanitation by calling for the reduction in "half of the proportion of people without sustainable access to safe drinking water and sanitation by 2015". Over 90% of the population of Costa Rica has access to improved water and sanitation, thus exceeding the water and sanitation targets for the Millennium Development Goals (MDGs). Despite having access to water and sanitation, little is known whether communities are only interested in access or if quality and quantity of water and sanitation systems are as equally as important. Target 7.c of the MDGs does not include water quality in the definition of safe water. Furthermore, the use of the words "safe" and "improved" in the target are often interchanged and can be misleading, especially when considering the impact of water quality on population health. In Costa Rica, households in the Nandamojo watershed have access to improved water and sanitation; it is unclear whether the drinking water is potable with respect to Costa Rican and the World Health Organization (WHO) water quality standards. The impact of leaking septic systems on human and environmental health is also unknown. Illnesses associated with recreational water are an increasing public health problem, causing a great burden of disease in bathers every year. The global health impact of infectious diseases associated with recreational water exposure has been estimated at around three million disability-adjusted life years (DALYs) per year, resulting in an estimated economic loss of around twelve billion dollars per year. Fecal and chemical contamination of recreational water is a concern, especially in areas of non-point source pollution. Health-based water monitoring is often conducted in recreational waters as a tool for assessing risk. In Costa Rica, recreational water sampling is conducted at coastal beach areas only, neglecting other surface waters used by residents and tourists. Community perspectives regarding recreational water use and the associated risks are limited. Understanding these perspectives will enable public health professionals to better target community needs, such as education and to address the concerns of participating communities. This dissertation was divided into three chapters. The first chapter explored community perceptions on improved water and sanitation, the second chapter assessed community water systems and the risk of acute diarrheal disease, and the third chapter captured community perceptions on recreational water use and the risk of waterborne illness. Methodologies for water sampling and analyses were used to assess water quality, while household interviews and focus groups were conducted to capture qualitative data. Results from the first chapter showed participants had positive perceptions towards their improved water and sanitation systems. Household interviews revealed almost half of the respondents had concerns with water quality, while less than 25% did not think their septic tanks leaked or overflowed during rain events. Focus group discussions revealed common themes. Participants identified water quality, health, pipes, water scarcity, odors, insects, and overflow/infiltration of water and sanitation to be important issues. Participants revealed convenience, improved health and safety and the lack of odors to be themes directly related to customer satisfaction of improved water and sanitation. Results from the second study revealed 57% of household samples had total coliform bacteria above the Costa Rican standard for safe drinking water exceeding the single standard limit of zero, while 61% failed the World Health Organization standard for fecal coliforms exceeding the single standard limit of zero. AGII was identified in 41 of the 378 household residents (11%). The odds ratio for AGII among household residents with a water sample positive for total coliforms was 1.88 (0.81-3.17). Fecal coliforms were statistically significant for those with AGII (OR = 3.19, 1.43-7.12). Regression modeling analyses revealed individuals with AGII and household drinking water positive for fecal coliforms to be statistically significant (OR = 3.01, 1.33 - 6.84), while other covariates (total coliforms, gender, treated water, and families) also had odds ratios greater than one, but were not significant. Results from the third chapter indicated most respondents felt recreational water sources, such as streams and rivers were contaminated with human, animal, and chemical wastes. Focus group participants also stated they did not use inland waters for recreational purposes for these reasons. However, many did admit using marine water for recreational bathing and felt these areas were not contaminated. These beliefs did coincide with the water quality results from freshwater sources, but not marine sources. Fecal coliform contamination was widespread throughout the watershed in freshwater sources. Marine water samples failed the World Health Organization (WHO) and Costa Rican recreational water standards for fecal coliform and enterococci in 36% and 6% of the samples, respectively. The overall results of this dissertation suggest that the definitions of improved water and sanitation have to include, at a minimum, water quality, water quantity, proper construction and containment of storage tanks, and oversight and maintenance of these systems. Given the challenges facing communities in the Nandamojo watershed regarding water and sanitation, it is essential for scientists, researchers, policy makers, water committees, health providers, and community members to design and implement strategies in water resource management and proper waste management. Communities and water committees would also be best served if they worked with government agencies to conduct concurrent testing of both recreational water and drinking water, especially since both them target many of the same parameters.

Veterinarians routinely conduct surgical operations on animals while veterinary technicians administer anesthetic gas to sedate the animal prior to an operation. One commonly used anesthetic agent in veterinary clinics is isoflurane. Veterinary workers have the potential to be exposed to this gas during surgical operations. The Occupational Safety and Health Administration (OSHA) does not have a specific Permissible Exposure Limit (PEL) for isoflurane, however The National Institutes for Health (NIH) does advise that workers should not be exposed to isoflurane in concentrations exceeding 2 parts per million (ppm) for an 8 hour Time Weighted Average (TWA). Animal clinics vary in the amount of surgeries they perform. Some clinics specialize in surgical services and therefore conduct a high volume of surgeries, while others that perform general practice work may conduct a far lower volume of surgeries. The research objectives for this study were to determine if veterinary workers are exposed to isoflurane levels above the concentration recommended by NIH and to quantify any disparity that exists between worker exposures at two veterinary facilities. A portable infrared ambient air analyzer (Miran SapphIRe, XL, ThermoScientific) was used to measure area concentrations of isoflurane and sorbent tube sampling via OSHA Method 103 was used to determine personal exposures to isoflurane. For the three days that sampling took place at the low volume clinic, personal sampling (samples taken in the breathing zone of a worker) during surgery showed that isoflurane concentrations exceeded the NIOSH recommended limit for 3 of the 5 samples when assuming a 6-hour gas exposure. When assuming exposure only lasted for the 2 hours that sampling occurred, 1 of the 5 samples exceeded the NIOSH recommended limit. For the three days that sampling was conducted at the high volume clinic, none of the 6 samples taken exceeded the NIOSH recommended exposure limit. The average isoflurane exposure to workers at the high volume clinic was 1.72 ppm while the average for the low volume clinic was 3.77 ppm. The average isoflurane exposure for veterinarians was 2.05 ppm and the average for veterinary technicians was 3.16 ppm. These data provide evidence that veterinary technicians may face higher exposures to isoflurane gas than veterinarians. There is also evidence that workers at the low volume clinic may be exposed to greater concentrations of isoflurane than workers at the high volume clinic. The average isoflurane concentrations were lower for the high volume clinic likely due to the fact that they relied only on an injectable sedative and no delivery of anesthetic gas for most operations. The high volume clinic also used more sophisticated equipment than the low volume clinic for the capture of waste gases.

Residences in Warren County, Kentucky, are characterized by high levels of residential radon, which is one of the radioactive daughter products of uranium. According to the United States Environmental Protection Agency (US EPA), radon exposure causes approximately 22,000 lung cancer deaths in the United States per year. The City of Bowling Green, in Warren County, is underlain by karst, an easily soluble limestone subsurface, which allows radon gas to travel easily through cracks and fissures. Carbonate rocks under Bowling Green are underlain by the Devonian Chattanooga Shale, a low-grade uranium ore and a potential source of radon gas. A digital map of the Chattanooga Shale was created using Arc GIS. A 1.6 km by 1.6 km (one-mile by onemile) grid for Warren County was generated, and depth data from oil wells within each grid cell were averaged to render the elevation of the top surface of the Chattanooga Shale in a digital format. A socio-economic GIS of Warren County was created using US Census Bureau and Property Value Administration data. The Chattanooga Shale and the socio-economic layers were correlated to test points that have high residential radon measurements to determine whether proximity to the shale layer or home type is the better predictor for radon risk. Once risks have been determined, management decisionmaking is simplified and resources can be targeted towards high need areas. Although this study determined that home type, i.e., size of the home and whether there is a basement present, does have a significant effect on residential radon levels, proximity to the top surface of the Chattanooga Shale does not have a significant effect in Warren County, Kentucky. Due to this lack of a geologic pattern it is recommended that radon mitigation systems be included in all new home construction and design.

This essay identifies and evaluates the most common environmental critiques made against nuclear energy development. Environmentalists articulate four major concerns: the destructive effects and health risks of uranium mining; the dangers posed by radiation releases and meltdowns; the difficult of nuclear waste disposal; and national security concerns, including nuclear weapons proliferation and the possibility of attack or sabotage. By characterizing and describing these concerns, we are better able to decide which problems are most compelling, and suggest possible policy-driven solutions.

Elevated levels of arsenic and other heavy metals like copper, aluminum, zinc, and selenium in drinking water are found to have deleterious effects on human health. Hence, finding methods for reducing their levels is critical. Iron-coated limestone is used as an adsorption material for the removal of heavy metals from drinking water. Removal of heavy metals by native or uncoated limestone was also observed and used for comparison to and evaluation of the improvement in removal efficiency from the ironcoated material. The removal efficiency with limestone was studied for different concentrations of heavy metals. Kinetic studies were done to determine the decrease in heavy metal concentration as a function of time using limestone. Inductively coupled plasma spectroscopy was used for metal analysis. The effective removal rate of copper and aluminum was found to be four hours and one hour, respectively. This method of removal by using limestone is cost effective, eco-friendly, and hence, of great potential importance for heavy metal removal. Iron-coated limestone is used as an adsorption material for the removal of heavy metals from drinking water. This project will investigate techniques to improve removal efficiency of heavy metals using limestone-based material through adsorption. This research will assist in the development of a granular adsorbent product that will remove metals and that can be manufactured and sold for use at the drinking water source, at point-of-use, or at point-of-entry. Limestone is readily available and its use for metals removal is relatively inexpensive. The technology can be adapted to small, rural water supply systems. Benefits of this research will include a low-cost treatment technology for source reduction that will reduce select metals to below drinking water standards.

Naturally occurring plant derived phenols can be degraded through bacteria in swine waste. Chlorinated phenols, which are not naturally present in the environment, are toxic and generated from industrial activities as such petrochemical, pharmaceutical, plastic, rubber, pesticide, iron, steel, paper production, coal conversion, wood preserving, and cellulose bleaching. Large scale coal gasification and carbonization plants are another source of chlorinated phenols. Although not normally present in the environment, chlorinated phenols are structurally similar to many plant derived phenolics. It is our hypothesis that bacteria located in swine wastes may also have the ability to degrade chlorinated phenols. Identifying situations (and organisms) in which degradation of pollutants occurs is important field of research. Experimental work was focused on measuring the degradation of seven chlorinated phenols in swine waste using solid-phase micro-extraction (SPME) and gas chromatography(GC). Microbes in the waste perform respiration or fermentation to obtain the energy they need to carry out their life processes. Fermentation is a process in which electrons are transferred from one organic substrate to another and which results in incomplete degradation of organic compounds. Anaerobic respiration is a process in which organic substrates are degraded completely to CO2, but using substances other than oxygen as the terminal electron acceptor (such as Fe(III), NO3- or SO42-). Anaerobic respiration using these alternative electron acceptors provides an easier pathway for degradation of aromatics than fermentation alone. Usually the abundance of these electron acceptors in waste is low since microbes consume them readily and thus they must be added to the mixture. Our work focused on development of methods for the quantification of chlorinated phenols in swine wastes and results of bioremediation research. In this study, chlorophenols were extracted by SPME and analysed by GC. This research project mainly focused on the anaerobic degradation of chlorophenols in swine waste. It was observed that the decreased concentration of the chlorophenols was likely due to partitioning of the chlorophenols to solids, sticking to glass bottles and by bacteria present in the swine waste. In summary, it was observed that by ANOVA and gas production analysis 2,6-dichlorophenol and 2,4,5-trichlorophenol were likely to be degraded by bacteria present in swine waste.

Increasing vehicle dependence in the United States has resulted in substantial emissions of traffic-related air pollutants that contribute to the deterioration of urban air quality. Exposure to urban air pollutants trigger a number of public health concerns, including the potential of inequality of exposures and health effects among population subgroups. To better understand the impact of traffic-related pollutants on air quality, exposure, and exposure inequality, modeling methods that can appropriately characterize the spatiotemporally resolved concentration distributions of traffic-related pollutants need to be improved. These modeling methods can then be used to investigate the impacts of urban design and transportation management choices on air quality, pollution exposures, and related inequality. This work will address these needs with three objectives: 1) to improve modeling methods for investigating interactions between city and transportation design choices and air pollution exposures, 2) to characterize current exposures and the social distribution of exposures to traffic-related air pollutants for the case study area of Hillsborough County, Florida, and 3) to determine expected impacts of urban design and transportation management choices on air quality, air pollution exposures, and exposure inequality. To achieve these objectives, the impacts of a small-scale transportation management project, specifically the '95 Express' high occupancy toll lane project, on pollutant emissions and nearby air quality was investigated. Next, a modeling method capable of characterizing spatiotemporally resolved pollutant emissions, concentrations, and exposures was developed and applied to estimate the impact of traffic-related pollutants on exposure and exposure inequalities among several population subgroups in Hillsborough County, Florida. Finally, using these results as baseline, the impacts of sprawl and compact urban forms, as well as vehicle fleet electrification, on air quality, pollution exposure, and exposure inequality were explored. Major findings include slightly higher pollutant emissions, with the exception of hydrocarbons, due to the managed lane project. Results also show that ambient concentration contributions from on-road mobile sources are disproportionate to their emissions. Additionally, processes not captured by the CALPUFF model, such as atmospheric formation, contribute substantially to ambient concentration levels of the secondary pollutants such as acetaldehyde and formaldehyde. Exposure inequalities for NOx, 1,3-butadiene, and benzene air pollution were found for black, Hispanic, and low income (annual household income less than $20,000) subgroups at both short-term and long-term temporal scales, which is consistent with previous findings. Exposure disparities among the subgroups are complex, and sometimes reversed for acetaldehyde and formaldehyde, due primarily to their distinct concentration distributions. Compact urban form was found to result in lower average NOx and benzene concentrations, but higher exposure for all pollutants except for NOx when compared to sprawl urban form. Evidence suggests that exposure inequalities differ between sprawl and compact urban forms, and also differ by pollutants, but are generally consistent at both short and long-term temporal scales. In addition, vehicle fleet electrification was found to result in generally lower average pollutant concentrations and exposures, except for NOx. However, the elimination of on-road mobile source emissions does not substantially reduce exposure inequality. Results and findings from this work can be applied to assist transportation infrastructure and urban planning. In addition, method developed here can be applied elsewhere for better characterization of air pollution concentrations, exposure and related inequalities.