Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: Towards Understanding of Aerosol Sources, Composition, and Toxicity in a Changing World

Abstract: Aerosols play a critical role in air pollution and climate change, which are two major environmental issues confronting the world today. Exposure to fine aerosols (particles with a diameter smaller than 2.5 μm, 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 geographical scales to better understand their impacts 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 the impacts of changing NOx and SO2 emissions from human activities on biogenic (natural) aerosol formation, composition and properties of aerosols from wildfires, and the prevalence of previously unrecognized contributions to ambient aerosols from aged biomass burning emissions. Through integrated detailed chemical characterization and in vitro assays, the toxicity of different types of organic aerosols are elucidated. We also introduce the Atmospheric Science and Chemistry mEasurement NeTwork (ASCENT), a new advanced, high-time-resolution, long-term measurement network in the U.S. for the characterization of aerosol chemical composition and physical properties on spatiotemporal scales not previously possible. Lastly, we present exciting new opportunities in elucidating the complex interplay of biogenic and biomass burning aerosols in response to changes in climate and human emissions, understanding air quality impacts of non-traditional sources including carbon capture and storage, and engineering high-throughput physiologically-relevant cellular platforms for aerosol toxicity screening. The ASCENT infrastructure will facilitate the integration of in-situ observations and remote-sensing measurements, and will enhance satellite-based observations, leading to the establishment of a global, integrated, long-term atmospheric research infrastructure for studying aerosols, trace gases, and clouds, and providing high-quality data for advancing research in climate, environmental change, and air quality.

Bio: Dr. Nga Lee "Sally" Ng is the Love Family Professor in the School of Chemical & Biomolecular Engineering, School of Earth & Atmospheric Sciences, and School of Civil & Environmental Engineering at the Georgia 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. 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 Editor-in-Chief of ACS ES&T Air. Dr. Ng's research contributions have 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), the first advanced aerosol measurement network in the United States.

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.