Dissertation
Observation, modeling, and analysis of air quality at the urban regional interface
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2022
DOI: 10.25820/etd.006666
Abstract
Air pollutants such as ozone, particulate matter, and nitrogen oxides negatively affect human health and impact the climate. Long term exposure to ozone increases the effects of asthma, heart disease, respiratory illnesses, and for at-risk groups of the population. Particles can deposit in the airways and lungs and are a cause of concern for the human population sensitive to respiratory illnesses.
Ozone pollution remains a challenge in coastal environments due, in part, to the unique meteorology induced by the presence of large bodies of water, or the lake-land breeze. The Lake Michigan Ozone Study 2017 was an intensive summer field campaign with the overall objective to better understand the formation and transport ozone and ozone precursors in the region. Three ozone periods occurred during the campaign: June 2-4, June 9-12, and June 14-16. The majority of the ozone events occurred on lake breeze days, but some did not. LMOS was the first field campaign to measure particles in the 1-3 nm range, with an average number concentration of 1.80x104 cm-3. Ultrafine particle number concentrations increased 47 % (significant by t-test) within a few minutes of the lake breeze arrival. The Photochemical Grid Model WRF-Chem reproduced the ozone variability well, but did underpredict peak ozone with a bias of -4.4 ppb for the coastal west sites. A decrease in NOx and VOCs emissions (~25 % and ~28 %, respectively) resulted in a 5-7 ppb decrease in ozone concentrations in rural areas and over the lake, but a 3-4 ppb increase in large urban areas during the daytime of the high ozone periods.
Globally, an estimated 1.5 million deaths in 2020 were attributed to tuberculosis (TB) and Vietnam is one of the 30 high TB burden countries. Few studies have focused on additional preventative measures despite poor adherence to lengthy prophylactic therapy. Identifying and assessing the impact of environmental factors (such as air pollution) on the early stages of TB infection is critical to developing additional preventative measures. Hanoi experiences poor air quality with 91 days exceeding the 24 hr Vietnamese standard for PM2.5 in 2018. The seasonal variability has been well-established with winter being the most polluted in general. However, the spatial variability is still highly uncertain. Using the two long-term measurements and sensors install during a tuberculosis study, there is a clear spatial variation over downtown Hanoi. Two global reanalysis products (MERRA-2 and CAMS) were compared to the average of the long-term measurement sites PM2.5. CAMS was better correlated (R = 0.721) with observations, but overestimated by a factor 2.8, on average. MERRA-2 captured the cleaner summer months, but underpredicted the winter months resulting in a lower correlation, R = 0.248, when compared to observations. Future research will be to develop a high resolution spatial map of air pollutants for use in health exposure models.
Details
- Title: Subtitle
- Observation, modeling, and analysis of air quality at the urban regional interface
- Creators
- Megan Brittany Christiansen
- Contributors
- Charles O Stanier (Advisor)Gregory R Carmichael (Advisor)Elizabeth A Stone (Committee Member)R Bradley Pierce (Committee Member)Thomas M Peters (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Chemical and Biochemical Engineering
- Date degree season
- Autumn 2022
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.006666
- Number of pages
- xviii, 137 pages
- Copyright
- Copyright 2022 Megan Brittany Christiansen
- Language
- English
- Description illustrations
- illustrations, graphs, tables, maps
- Description bibliographic
- Includes bibliographical references.
- Public Abstract (ETD)
Ozone pollution at the Earth’s surface increases the effects of asthma and heart disease in humans and damages the life cycle of plants and crops. Additionally, particles have adverse effects on the respiratory system of humans. Particles and ozone precursors, nitrogen oxides and volatile organic compounds, have natural and man-made sources, such as motor vehicles, power plants, soil, vegetation, and biomass burning.
Spring and summertime ozone pollution remains a challenging air quality problem along the coast of Lake Michigan. Production of ozone over Lake Michigan combined with onshore daytime lake breeze airflow increases ozone concentrations preferentially at locations within a few kilometers of the shore. A field campaign was developed to provide a more detailed dataset to supplement the existing measurement network. The overall goal of the campaign was to better understand the ozone formation and transport over the lake to the shoreline. Three distinct high ozone periods were identified where most episodes occurred following a lake breeze. Model sensitivity analysis shows a decrease in ozone concentrations in rural areas with a decrease in man-made nitrogen oxides and volatile organic compounds emissions.
Tuberculosis is a leading cause of death by infectious disease and Vietnam is one of the 30 high burden countries. Air pollutants, such as particulate matter (PM), are likely to contribute to the risk of developing many pulmonary diseases. The annual average of PM in Hanoi is higher than the national standard and 91 days in 2018 exceeded the standard with some more than a factor of 4 higher. There are limited ground station observations and the global models have too low a resolution to resolve spatial variation in Hanoi. An additional five PM sensors were deployed during a tuberculosis study in 2018 and a preliminary analysis supports the high variability in the downtown area. Future work in Hanoi will be to develop a high resolution spatial map over Hanoi of air pollutants in support of health exposure model development.
- Academic Unit
- Chemical and Biochemical Engineering
- Record Identifier
- 9984363058002771
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