School of Civil and Environmental Engineering

Ph.D. Thesis Defense Announcement

Modeling of factors impacting atmospheric formic acid, ozone and PM2.5 dynamics

By:

Ziqi Gao

Advisor: 

Dr. Armistead G. Russell (CEE)

Committee Members:  

Dr. Jennifer Kaiser (CEE), Dr. Rodney J. Weber (EAS) Dr. Nga L. Ng (CHBE), Dr. Cesunica Ivey (CEE, UC Berkeley)

Date and Time:  Thursday April 13, 2023 11:00am

Location: Mason 2119 / Zoom: https://gatech.zoom.us/j/97269030665

Complete announcement, with abstract, is attached.

Elevated concentrations of air pollutants have been linked to an increased risk of respiratory diseases, cardiovascular diseases, lung cancer, and mortality rate. Multiple atmospheric processes, such as emissions, chemical reactions, transport, and deposition, can affect ozone formation, particulate matter (PM2.5), and organic acids. Although the government has set many regulations to reduce the emissions of pollutant precursors, the actual impacts of these regulations are highly sensitive to external factors such as local meteorology, source distributions, and large-scale climatic patterns, such that emissions reductions could be ineffective or could even result in worse air pollution. The effectiveness of the regulations can be evaluated after isolating the impacts of external factors. This can help policymakers make future regulations to mitigate air pollutant concentrations more effective and efficient.
This work applied several models, ranging from chemical transport, box, and empirical models, to assess the impact of existing national and state emission reduction regulations on emissions and air pollutants concentrations. These models were also used to evaluate and quantify the impact of the main drivers and processes (e.g., emissions, meteorological impacts, chemical reactions, etc.) that impact air quality and predict potential air pollution concentrations in future years. In looking at the impact on both anthropogenic and biogenic emissions, we found that 1) A bi-directional emission-deposition process has more impact on formic acid formation than photooxidation reactions, 2) Emissions largely control peak ozone and PM2.5concentrations as well as PM2.5chemical composition trends, though meteorology impacts daily variability and can lead to increases in annual peak ozone concentrations despite emissions reductions. 3) In the future, meteorological impacts will significantly impact all air pollutant concentrations with the emissions reduction and affect the attainment of pollutant standards. Thus, while historical and future air pollution regulations can (or, in some cases, have) attain pollutant standards, meteorology, and climatic effects may endanger consistent attainment.