Master of Science

thesisTwo years of speciated atmospheric mercury data in the Intermountain West are examined for annual, seasonal, and diurnal patterns, as well as influences of precipitation. Mercury is a pollutant in the atmosphere that occurs as three species: gaseous elemental mercury (GEM), particulate-bound mercury (PBM), and gaseous oxidized mercury (GOM). Mercury can enter ecosystems from the atmosphere via wet and dry deposition. In aquatic ecosystems, it can convert to the neurotoxin methylmercury, which has prompted consumption advisories for both fish and waterfowl. A Tekran ambient air mercury monitor was deployed at a site (UT96) near the Great Salt Lake, Utah as part of the Atmospheric Mercury Network (AMNet). UT96 has the only such detector in continuous operation in Utah with two years of data (July 2009 - June 2011). All three mercury species exhibit right-skewed distributions and vary in concentration over multiple orders of magnitude. GEM is the dominant species with a median concentration of 1.58 ng m-3 (range 0.25 - 64.47 ng m-3). PBM has a median concentration of 5.7 pg m-3 (range 0 - 803.2 pg m-3), while GOM has a median concentration of 2.6 pg m-3 (range 0 - 225.6 pg m-3). The sporadic nature of the extremely high GEM and PBM events suggest that they primarily result from local/regional emissions. In contrast, extremely high GOM events depend strongly on time of day and season, suggesting a connection to meteorological conditions. All three species exhibit statistically significant seasonal and diurnal patterns. GOM exhibits the strongest seasonal pattern, peaking during summer with median summer concentrations a factor of six greater than median winter concentrations. GEM and PBM peak during winter. All three species exhibit statistically significant diurnal patterns for at least part of the year. GOM has the most pronounced diurnal cycle, particularly during summer.Median concentrations of GOM during the afternoons of summer months are greater than 20 pg m-3, while median concentrations overnight are below 5 pg m-3. GEM and PBM both exhibit minima in concentrations during the afternoons, and both exhibit the largest diurnal variation amplitude during summer. Neither GEM nor PBM exhibit a statistically significant diurnal pattern during winter. An examination of the influences of precipitation on mercury concentrations indicates that precipitation scavenges GOM more efficiently than PBM, and that the scavenging increases as the amount of precipitation increases. Mixed precipitation scavenges PBM better than either rain or snow alone. The median GOM concentration during rain, snow, and mixed precipitation were all below the method detection limit (MDL), and could not be distinguished. There are some indications in the data that rain may promote slightly elevated concentrations of GEM

Doctor of Philosophy

dissertationThe valleys of northern Utah, where most of Utah’s population resides, experience episodic air pollution events well in excess of the National Ambient Air Quality Standards. Most of the events are due to an accumulation of particulate matter during persistent cold air pools in winter from both direct emissions and secondary chemical reactions in the atmosphere. High wintertime ozone concentrations are occasionally observed in the Uintah Basin, in addition to particulate matter. At other times of the year, blowing dust, wildland fires, fireworks, and summertime ozone formation contribute to local air pollution. The objective of this dissertation is to investigate one facet of the health effects of Utah’s air pollution on its residents: the acute impacts of air pollution on gastrointestinal (GI) disease. To study the health effects of these episodic pollution events, some measure of air pollution exposure must be matched to the health data. Time and place are used to link the health data for a person with the pollution data. This dissertation describes the method of kriging data from the sparse pollution monitoring network to estimate personal air pollution history based on the zip code of residence. This dissertation then describes the application of these exposure estimates to a health study on GI disease. The purpose of the GI study is to retrospectively look at two groups of patients during 2000-2014: those with autoimmune disease of the GI tract (inflammatory bowel disease, IBD) and those with allergic disease of the GI tract (eosinophilic esophagitis, EoE) to determine whether disease exacerbations occur more commonly during and following periods of poor air quality compared to periods of good air quality. The primary analysis method is case crossover design. In addition to using the kriged air pollution estimates, the analysis was repeated using simpler empirical estimation methods to assess whether the odds ratios are sensitive to the air pollution estimation method. The data suggests an association between particulate matter smaller than 2.5 microns and prednisone prescriptions, gastrointestinal infections in general, clostridium difficile infections specifically, and hospitalizations among people who have at least five entries of IBD diagnosis codes in their medical records. EoE exacerbations appear to be associated with high concentrations of particulate matter as well as ozone

Air pollution and gastrointestinal diseases in Utah

The valleys of northern Utah, where most of Utah’s population resides, experience episodic air pollution events well in excess of the National Ambient Air Quality Standards. Most of the events are due to an accumulation of particulate matter during persistent cold air pools in winter from both direct emissions and secondary chemical reactions in the atmosphere. High wintertime ozone concentrations are occasionally observed in the Uintah Basin, in addition to particulate matter. At other times of the year, blowing dust, wildland fires, fireworks, and summertime ozone formation contribute to local air pollution. The objective of this dissertation is to investigate one facet of the health effects of Utah’s air pollution on its residents: the acute impacts of air pollution on gastrointestinal (GI) disease. To study the health effects of these episodic pollution events, some measure of air pollution exposure must be matched to the health data. Time and place are used to link the health data for a person with the pollution data. This dissertation describes the method of kriging data from the sparse pollution monitoring network to estimate personal air pollution history based on the zip code of residence. This dissertation then describes the application of these exposure estimates to a health study on GI disease. The purpose of the GI study is to retrospectively look at two groups of patients during 2000-2014: those with autoimmune disease of the GI tract (inflammatory bowel disease, IBD) and those with allergic disease of the GI tract (eosinophilic esophagitis, EoE) to determine whether disease exacerbations occur more commonly during and following periods of poor air quality compared to periods of good air quality. The primary analysis method is case crossover design. In addition to using the kriged air pollution estimates, the analysis was repeated using simpler empirical estimation methods to assess whether the odds ratios are sensitive to the air pollution estimation method. The data suggests an association between particulate matter smaller than 2.5 microns and prednisone prescriptions, gastrointestinal infections in general, clostridium difficile infections specifically, and hospitalizations among people who have at least five entries of IBD diagnosis codes in their medical records. EoE exacerbations appear to be associated with high concentrations of particulate matter as well as ozone