Aerosol Scientist Spotlight: Nancy Lei

Ziying (Nancy) Lei, PhD

Assistant Professor, University of Tennessee-Knoxville

Interviewed by Lindsay Yee, Assistant Project Scientist, University of California, Berkeley

LY: How did you get involved in the aerosol science community?

NL: Growing up in China, I witnessed how air pollution could take away something as precious as a clear blue sky. I always wanted to do something meaningful—something that could help people breathe cleaner air and protect our planet. When I came to the U.S. to pursue my master’s degree in Civil and Environmental Engineering at The Ohio State University, I wasn’t sure how to turn that passion into action. Then, after reviewing my application, Dr. Andrew May reached out and asked if I was interested in aerosol research. That moment changed everything. I began studying the optical properties of black carbon aerosols, and it felt like stepping into an entirely new world. This research experience ignited my curiosity and set me on a path to explore the complexities of aerosol science. Since then, my passion for understanding aerosols has only deepened. What started as a drive to address air pollution has evolved into a broader mission—understanding how aerosols affect our environment, influence clouds, and ultimately impact global climate. Aerosol science isn’t just research to me; it’s a way to contribute to something bigger, something that bridges air quality, climate, public health, and the future of our planet.

LY: Which people or programs in our field have been the most influential to you and your path, or who have most influenced your ideas about aerosol science and technology?

NL: I have been fortunate to have incredible mentors who have shaped my path in aerosol science, especially my Ph.D. advisor, Dr. Andrew Ault, and my postdoc advisor, Dr. Sarah Brooks. They have been true role models, and their passion for research, dedication to their students, and enthusiasm for discovery have brought so much excitement into my own career. Dr. Ault taught me the power of detailed single-particle analysis using cutting-edge microspectroscopy techniques. I still remember the first time I saw individual particles through a microscope—it felt like discovering an entirely new world, something our eyes could never see on their own. He also gave me opportunities to lead novel and collaborative research, allowing me to apply my interdisciplinary background in meaningful ways.

When I started my postdoc, Dr. Brooks introduced me to field research, inviting me to join the DOE TRACER campaign, where the TAMU team built a van to chase thunderstorm air masses. Driving straight into storms to collect data felt like stepping into Twister, it was thrilling, chaotic, and an experience I’ll never forget. That DOE campaign deepened my passion for field research, showing me the importance of connecting lab studies with real-world atmospheric processes. Sarah also trained me in using a custom-designed ice nucleation array to study ice-nucleating particles (INPs) and how to operate a continuous flow diffusion chamber for real-time INP measurements. These experiences and the guidance from my mentors have been instrumental in my growth as an aerosol scientist and continue to inspire my research today.

LY: What is the most interesting research contribution you’ve made so far?

NL: I think the most interesting research contribution I’ve made so far is developing a novel method to measure aerosol acidity and discovering how aerosol acidity influences aerosol ice nucleation ability. Measuring aerosol acidity has been a challenge in atmospheric science, especially for individual submicron particles. For many years, there was no direct method to determine the pH of submicron atmospheric particles, despite the fact that pH plays a crucial role in multiphase reactions, liquid-liquid phase separation, gas-particle partitioning, and ultimately, aerosol climate and health effects. My research using polymer degradation provided an important first step toward addressing this critical gap. I was very excited to discover that more acidic aerosols freeze at lower temperatures due to the temperature-dependent dissociation of sulfuric acid. It has been incredibly rewarding to contribute to fundamental research that helps us better understand the complex behavior of atmospheric aerosols and their role in cloud formation.

Papers link: https://pubs.acs.org/doi/10.1021/acs.analchem.9b05766
https://pubs.acs.org/doi/10.1021/acsearthspacechem.3c00242

LY: What challenges were unexpected as you began and continue to grow your company/research group?

NL: One of the unexpected challenges I faced was building my research lab from scratch in such a short amount of time. When I started as a new faculty member, I was so excited to have seven students interested in joining my lab for research rotations, but honestly, I was also a bit overwhelmed. I was concerned about how I would compete with more established labs that has full of cool instruments. I was balancing the setup of a new experimental lab, managing lab renovations, preparing for teaching, writing proposals, and launching my own research program. Looking back, those first few months felt like a whirlwind. I was figuring out everything at once—how to be a mentor, how to build a supportive research environment, and how to balance all the moving parts of starting a lab. I’m incredibly grateful to the mentors and colleagues who shared their advice and encouragement during that time. It’s still a learning process, but now I see how much growth came from those early challenges. Building my lab has been one of the most rewarding experiences of my career, and it’s made me even more excited about the work we’re doing and the team we’re building together.

LY: Are there new research directions that you see as particularly important or interesting?

NL: I am particularly excited about aerosol-climate interactions, especially as extreme weather events become more frequent and winter periods continue to shorten. One of the biggest uncertainties in climate predictions remains aerosol-cloud interactions, largely due to the complex nature of aerosols and their evolving properties in the atmosphere. A key area of interest for me is measuring aerosol mixing state at the single-particle level. Understanding how different aerosol components interact within individual particles is crucial for improving climate models and accurately predicting their effects on cloud formation and radiative forcing. Advances in microspectroscopy and real-time high-resolution mass spectrometry provide exciting opportunities to explore these interactions in greater detail.

I am also very interested in biogenic aerosols in the southeastern U.S.. Over the past several years, sulfate concentrations have significantly decreased, altering the chemical composition of atmospheric aerosols in this region. To me, this shift presents an exciting opportunity to study the new dominant multiphase atmospheric chemistry of biogenic aerosols, particularly their role in secondary organic aerosol (SOA) formation and cloud microphysics. These research directions are critical for reducing uncertainties in aerosol-cloud interactions, improving climate models, and understanding how atmospheric chemistry is evolving in response to policy changes and environmental shifts. There is still so much to discover, and I’m excited to contribute to these emerging questions in aerosol science.