AAAR 39th Annual Conference

Plenary Sessions


Tiny critters, huge impacts: Ocean microbes, climate, and health

Kimberly A. Prather, Distinguished Chair in Atmospheric Chemistry, Scripps Institution of Oceanography, University of California, San Diego

In the 1990’s, major advances enabled real-time measurements of the size and chemical composition of atmospheric aerosols. Since then, numerous field and lab studies have led to an increased understanding and appreciation for the impact of atmospheric aerosols on human health and climate. One of the largest remaining gaps in our understanding involves how biological processes in the ocean influence the composition of the marine atmosphere. Given their role in seeding clouds and affecting climate, it is critical to understand the factors controlling the size and composition of marine aerosols. This plenary lecture will provide an overview of studies in the NSF Center for Aerosol Impacts on Chemistry of the Environment (CAICE; Over the past decade, CAICE scientists have successfully transferred the physical, chemical, and biological complexity of the ocean/atmosphere system into the laboratory at Scripps Institution of Oceanography. An overview will be provided of the key advances in CAICE studies and how this isolated ocean-in-the-lab approach has improved our understanding of the ocean on our atmosphere and climate. Finally, a discussion will be presented of recent studies investigating the factors controlling the ocean-to-atmosphere transfer of bacteria and viruses, including the SARS-CoV-2 virus that leads to COVID-19, and the implications for the health of residents living in and near coastal regions.

Professor Kimberly A. Prather is the Distinguished Chair in Atmospheric Chemistry at Scripps Institution of Oceanography and the Department of Chemistry and Biochemistry at University of California, San Diego. Professor Prather invented aerosol time-of-flight mass spectrometry (ATOFMS) that allows in-situ atmospheric measurements of the evolution of the size and chemical composition of individual aerosol particles. This instrument has been used in ground-based, shipboard, and aircraft studies worldwide to advance our understanding of the major sources, composition, and reactivity of atmospheric aerosols.

Professor Prather is the founding Director of the NSF Center for Aerosol Impacts on Chemistry of the Environment (CAICE), an NSF Center for Chemical Innovation. CAICE scientists have transferred the ocean-atmosphere system into the laboratory to investigate how phytoplankton, bacteria, and viruses in the ocean influence atmospheric chemistry, clouds, and climate. Recognition for her work includes being an elected member of the American Academy of Arts and Sciences, National Academy of Engineering, and National Academy of Sciences, and an elected fellow of AAAS and AGU. Some of her major awards include the AAAR Kenneth T. Whitby Award, ACS Frank H. Field & Joe L. Franklin Award for Outstanding Achievement in Mass Spectrometry, and the Haagen-Smit Clean Air Award.


Electronic Cigarette: The Knowns, Known Unknowns, and Unknown Unknowns

Yifang Zhu, University of California, Los Angeles Fielding School of Public Health

Electronic cigarettes (E-cigs) are battery-operated devices gaining increasing popularity as an alternative to tobacco cigarettes. The global e-cig market is projected to reach $48.9 billion by 2025, with more than 70% of the market in North America and Europe. The number of e-cig users has also increased markedly, especially among adolescents. Yet, little is known regarding the physiochemical characteristics or health-related effects for the large array of aerosols that are inhaled and exhaled by e-cig users. With the rapid increase in e-cig users worldwide, secondhand exposure to e-cig aerosols has also become a serious public health concern. Through a series of studies, we have systematically characterized mainstream and secondhand e-cig aerosols in chambers, in laboratory indoor environments, and in vape shops. We found that e-cig device voltage, puff duration, puff volume, and e-liquid ingredients are important factors determining physiochemical properties of e-cig aerosols. We also summarize the evidence on the effects of e-cigs on indoor air quality, chemical compositions of mainstream and secondhand e-cig aerosols, and associated respiratory and cardiovascular effects. The use of e-cigs in indoor environments leads to high levels of fine and ultrafine particles similar to tobacco cigarettes. Concentrations of chemical compounds in e-cig aerosols are generally lower than those in tobacco smoke, but a substantial amount of vaporized propylene glycol, vegetable glycerin, nicotine, and toxic substances, such as aldehydes and heavy metals, have been reported. Exposures to mainstream e-cig aerosols have biologic effects, but only limited evidence showing adverse respiratory and cardiovascular effects in humans. Long-term studies are needed to better understand the dosimetry and health effects of exposures to secondhand e-cig aerosols. Future studies also need to focus on identifying vulnerable populations and monitor places that may contribute to high levels of secondhand exposures.

Dr. Yifang Zhu is a professor of Environmental Health Sciences at UCLA Fielding School of Public Health where she serves as the senior associate dean for academic programs. Her research focuses on measuring and modeling particle emissions, transport, and transformation in both outdoor and indoor environments as well as assessing and mitigating the associated adverse health effects. Her scholarship and creativity has been recognized by several national awards, including the Walter A. Rosenblith New Investigator Award from the Health Effects Institute, the Faculty Early Career Development (CAREER) Award from the National Science Foundation, and the Haagen-Smit Prize from Atmosphere Environment. Dr. Zhu was appointed to California Air Resource Board’s Research Screening Committee in January 2014. She has also served as an editor for Aerosol and Air Quality Research, a guest editor for Aerosol Science and Technology, and is a member of the editorial board for Atmospheric Environment. She has been attending AAAR meetings for more than 20 years since she started her doctoral training with Dr. William Hinds in 1999. Over the years, she has served on the AAAR technical program committee as a working group chair and many times as a session chair and student poster competition judge. She is committed to grow the AAAR community by mentoring young aerosol scientists and to apply her knowledge, dedication, and leadership skills to AAAR for years to come.


Aerosols in Chemistry and the Chemistry of Aerosols

Murray Johnston, Professor of Chemistry and Associate Dean for the Natural Sciences, University of Delaware.

Aerosols provide a unique medium for studying chemical processes, while knowledge of chemical processes helps us understand and predict aerosol formation and growth in the atmosphere. In this presentation, the connection between aerosols and chemistry will be discussed, drawing from recent studies in our laboratory as well as the broader scientific community. From the “aerosols in chemistry” perspective, we will explore how chemical processes in aerosols may differ from those studied exclusively within a bulk phase or at an interface between two phases. Aerosols as media for performing chemical reactions provide the opportunity fine tune the interface-to-volume ratio and thereby control the relative reaction rates in the two regions. From the “chemistry of aerosols” perspective, we will explore how chemical processes contributing to growth of ultrafine particles, 100 nm in diameter and below, may change with particle diameter. The growth of smaller particles tends to be driven by interfacial processes while that of larger particles tends to be driven by volume processes, and the transition from one to the other occurs as particles grow. Finally, from both perspectives simultaneously, we will explore how aerosol processes can be exploited for chemical analysis – whether the motivation is molecular characterization of a bulk phase or airborne particulate matter.

Murray Johnston is Professor of Chemistry and Associate Dean for the Natural Sciences at the University of Delaware. He received his B.S. degree in chemistry from Bucknell University and Ph.D. degree in chemistry from the University of Wisconsin, Madison. Johnston’s research involves the development and application of mass spectrometry for laboratory and field studies of airborne particulate matter. He has received the Outstanding Scholar Award from the College of Arts and Sciences at the University of Delaware, the Delaware Section Award from the American Chemical Society, and the Benjamin Y. H. Liu Award from AAAR. He has served AAAR in several capacities including Board of Directors, Treasurer, Conference Chair, and President, and is a Fellow of AAAR. He has served on several journal editorial advisory boards including Aerosol Science and Technology, and two committees of the National Academy of Sciences involving aerosol detection.


Mechanisms of Nanoparticle Formation and their Health Effects

Angela Violi, University of Michigan

An important step in predicting the growth of soot nanoparticles is understanding how gas phase variations affect the formation of their aromatic precursors. Once formed, these aromatic structures begin to assemble into nanoparticles and, regardless of the clustering process, the molecular properties of the aromatic precursors play an important role.

This presentation is divided in two parts: first we report on a detailed study of compounds formed in flames discussing formation mechanisms and their relative importance according to the environment. Using a unique computational model based on Monte Carlo techniques (named SNapS2), we are able to predict the structure and chemical evolution of various polycyclic aromatic compounds (PACs) and nanoparticle. PACs predicted in various conditions show diverse chemical properties, including aliphatic chains, five-membered, and heteroaromatic rings. Using graph theory and network analysis, we investigated the complex reaction network generated by SNapS2 and determined that the growth pathways of many PACs center around a few stable structures that also promote oxygen addition reactions due to their morphology and long lifetimes.

In the second part of the talk, we will address the health effects of PACs and nanoparticles. Indeed, one of the main issues related to the health effects of pollutants is their ability to cross biological cells, i.e. the transport through a physiological cellular membrane. The behavior of nanoparticles in a biological matrix is a very complex problem that depends not only on the type of nanoparticle but also on its size, shape, phase, surface charge, chemical composition, and agglomeration state. We present a theoretical model that predicts the average time of entry of nanoparticles in lipid membranes, using a combination of molecular dynamics simulations and statistical approaches. The model identifies four parameters that separate the contributions of molecules characteristics (i.e., size, shape, solubility) from the membrane properties (density distribution). The robustness of the model is supported by experimental data carried out in lipid vesicles encapsulating graphene quantum dots as nanoparticles. The new model, named LDA, is applied to the permeation of PAHs through various cellular membranes. Given the high level of interest across multiple areas of study in modulating intracellular targets, and the need to understand and improve the effects of nanoparticles and to assess their effect on human health (i.e., cytotoxicity, bioavailability), this work contributes to the understanding and prediction of interactions of nanoparticles and environmental media that affect fate, transport and risk.

Professor Violi is the Arthur Thurnau Professor at the University of Michigan with appointments in the Departments of Mechanical Engineering, Chemical Engineering and Biophysics. Professor Violi’s research interests lie at the intersection of, nanoscience, combustion science and biomedical science. Her research involves the study, through modeling and simulation, of nanoparticle formation, the impact of these particles on the environment, and human health, as well as the design of nanomaterials for biomedical applications, such as control of bacterial communities. The common intellectual thread among those activities is the application of multiscale modeling approaches coupled with pertinent longer scale processes and systems. She has pioneered the development of computational nanoscience in the field of combustion in essentially single-handed fashion developing Multiscale Computational methods to study long time and large-scale phenomena.

In addition to the combustion field, Angela has made critical inroads into the previously uncharted territory of atomistic simulations of supramolecular complexes between nanoscale structures and biological systems. The molecular dynamics methods developed by Angela enabled accurate predictions of the structures and properties of chiral graphene quantum dots, as important nanomaterials with optical and electronic properties (Suzuki et al., ACS Nano 2016) and for applications in biology for the big problem of antibiotic-resistance (Wang et al ACS Nano. 2019, 13, 4278).

What sets Prof. Violi research apart is its comprehensive approach to complex phenomena; evidence of this is her extremely broad research portfolio and the impact that she has in the various fields. This statement is supported by the numerous invited presentations she has given over the years not only in the field of combustion, but also at multiple Gordon Conferences, at the ECI Nanotechnology in medicine in Austria, at AIChE meetings, and the International congress on health effects (PIC) in Korea and Umea, Sweden.

Angela is also dedicated and committed to students. She has also received the 2020 Thurnau professorship as testament to her commitment to students, excellence in mentoring and demonstrated impact and demonstrable impact on students’ intellectual development and lives.

The far-reaching impact of her research portfolio has been celebrated by numerous awards. Among the latest ones, Angela has received 2020 Aspire, Advance and Achieve Mentoring Award, U-M Women in Science and Engineering Program, the 2020 J. Cordell Breed award for women leaders, by the Society of Automotive Engineers, ASME George Westinghouse Silver Medal. In 2018 she became Fellow of the Combustion Institute.


Fine Particulate Matter: Interpreting Satellite Observations to Advance Understanding for Health Applications

Randall V. Martin, Raymond R. Tucker Distinguished Professor, Washington University

Exposure to fine particulate matter (PM2.5) is the leading global environmental determinant of longevity. However, ground-level monitoring remains sparse in many regions of the world. Satellite remote sensing of aerosol optical depth offers global data to address this observational gap. Global modeling plays a critical role in relating satellite observations to ground-level concentrations. The resultant satellite-based PM2.5 estimates indicate pronounced variation around the world, with implications for global health and insight into the association of PM2.5 with health outcomes. Sensitivity simulations with the GEOS-Chem model provide information on the sources of ambient fine particulate matter contributions that affect human health. These capabilities offer information about the effects of COVID-19 lockdowns on air quality. The Surface Particulate Matter Network (SPARTAN) is designed to evaluate and enhance satellite-based PM2.5 estimates. Advanced high-performance modeling offers increasingly fine resolution to connect across scales. This talk will highlight recent advances in combining satellite remote sensing, global modeling, and ground-based measurements to improve understanding of PM2.5 for health applications from global toward urban scales.

Randall V. Martin is the Raymond R. Tucker Distinguished Professor at Washington University. His research is at the interface of satellite remote sensing, global modeling, and measurements, with a focus on characterizing atmospheric composition to inform effective policies surrounding major environmental and public health challenges ranging from air quality to climate change. He received his BS in Engineering from Cornell University, MSc in Environmental Change and Management from Oxford University, PhD in Engineering Sciences from Harvard University, and postdoctoral training at the Harvard-Smithsonian Center for Astrophysics. His activities include serving as Co-Model Scientist for the GEOS-Chem global model of atmospheric composition, serving on multiple satellite science teams, and leading the global Surface Particulate Matter Network. His professional honors include a Steacie Memorial Fellowship, an AGU Ascent Award, and being named a Highly Cited Researcher.

Dates to Remember

September 18, 2021
Hotel Reservation Cutoff Date 

October 18 - 22, 2021
AAAR 38th Annual Conference
Albuqureque, New Mexico

Code of Conduct


Albuquerque Convention Center
401 2nd St NW

Albuquerque, New Mexico


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