CBE Colloquia - Towards Understanding of Aerosol Sources, Composition, Toxicity in a Changing World
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Climate change and air pollution are two major environmental issues confronting the world today, and they are intricately related. Aerosols play a critical role in both. Exposure to fine particulate matter pollution (PM2.5) ranks among the top ten global health risks. Organic aerosols dominate ambient PM2.5 and have important impacts on air quality, climate, and human health. A major fraction of organic aerosols are secondary organic aerosols (SOA), formed from atmospheric oxidation of a multitude of volatile organic compounds followed by gas-particle partitioning. With continued shifts in emissions, changes in climate, and increases in the frequency and intensity of wildfires, the sources, composition, and properties of aerosols are constantly evolving, posing a critical need to investigate these changes across different scales to better understand their impact on climate and human health in a changing world. Towards this end, we conducted integrated laboratory studies, ambient field measurements, and cellular toxicity experiments to investigate the fundamental chemical processes driving aerosol formation and composition, as well as the health effects of aerosols. We present new insights into how changing NOx and SO2 emissions from human activities impact biogenic (natural) aerosol formation, as well as understanding of aerosol formation from wildfire emissions. Through integrated detailed chemical characterization and in vitro assays, the toxicity of different types of organic aerosols is elucidated. We also introduce the Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT), the first advanced, high-time-resolution, long-term measurement network in the United States for the characterization of aerosol chemical composition and physical properties on spatiotemporal scales not previously possible.
Dr. Nga Lee “Sally” Ng is the Elizabeth W. Gilloon Professor of Environmental Science and Engineering at the California Institute of Technology. She earned her doctorate in Chemical Engineering from the California Institute of Technology and was a postdoctoral scientist at Aerodyne Research Inc. She previously held the Love Family Professorship in the School of Chemical & Biomolecular Engineering, School of Earth & Atmospheric Sciences, and School of Civil & Environmental Engineering at the Georgia Institute of Technology. Dr. Ng’s research focuses on understanding the chemical mechanisms of aerosol formation and composition, as well as their health effects. Her group combines laboratory chamber studies and ambient field measurements to study aerosols using advanced mass spectrometry techniques. Dr. Ng serves as the inaugural Editor-in-Chief of ACS ES&T Air. Her research contribution has been recognized by a number of awards, including the Sheldon K. Friedlander Award and the Kenneth T. Whitby Award from the American Association for Aerosol Research (AAAR) and the Ascent Award from the American Geophysical Union (AGU). Dr. Ng is currently leading collaborative efforts to establish the Atmospheric Science and mEasurement NeTwork (ASCENT) in the United States.