Atmospheric Chemistry and Air Quality


UC Davis' aerosol mass spectrometer for measuring the size and composition of particles in the atmosphere.

Students in the atmospheric chemistry and air quality program at Davis study a wide range of questions regarding the emission, transformation, transport and deposition of air pollutants. Research projects include measurement and modeling of emission, deposition and dispersion on scales ranging from the microscale processes around individual plants to mesoscale flows over an entire state. The study of air quality problems is multi-disciplinary as is reflected by the diversity of training and departmental affiliation of the Graduate Group members associated with this specialty.

Select a faculty member's name below to visit their web page.

For further information, visit the Air Quality Research web site.

Cort Anastasio

Professor Anastasio's research explores the chemistry and composition of tropospheric aerosol particles and cloud/fog drops, typically using laboratory studies. Reactions in these particles and drops are an important component of the biogeochemical cycles of nutrients and pollutants that can alter atmospheric composition and affect climate and impact human health. Projects explore both the chemistry of anthropogenic air pollutants as well as the chemistry of the natural "background" atmosphere. Current research activities include: examining the photoformation of secondary organic aerosol in cloud and fog drops; exploring oxidant generation by airborne particles in a surrogate lung fluid; and quantifying the photochemical reactions of trace species in snow and their impacts on the atmospheric boundary layer.

Chris Cappa

Professor Cappa's research is focused on the study of physical, chemical and optical properties of atmospheric aerosols. His group uses state-of-the-art analytical techniques in the lab and the field to characterize how and why aerosol properties vary in both time and space.

Ann M. Dillner

Dr. Dillner conducts research on particulate matter air pollution in the atmosphere. A primary motivation for much of her work is visibility degradation by particulate matter at National Parks in the US and she is a part of the Interagency Monitoring for Protected Visual Environments (IMPROVE) program at UCDavis. Current and recent projects include studying the volatility and reactivity of organic particles after collection and before traditional analysis, developing a method utilizing FTIR to quantify particulate organic compound classes for use at a National Park in Arizona, characterizing and developing improved methods for particulate matter sampling for the IMPROVE network, developing a size distribution cluster technique to determine sources of elemental and trace metal particulate matter, characterizing bioaerosols and fine and ultrafine particles for health effects studies.

Ian Faloona

Professor Faloona works to bridge the traditional fields of geophysical turbulence and chemistry with emphasis placed on an interdisciplinary understanding of the physical and chemical principles that control trace gas concentrations and their fluctuations in the atmosphere and ocean. The turbulent planetary boundary layers that lie adjacent to the interfaces of the earth, ocean, and sky play host to a great variety of exchange processes that are critical to understanding the climate system. Scientific investigation into such processes is undertaken by Professor Faloona's group on aircraft, ocean vessels, towers, and in the lab using a wide array of optical and mass spectrometric analytical techniques. The ultimate objective is to use the data to learn about both chemical reactions rates and the meteorological mixing processes, which strongly control the ability of compounds to react with one another. His group pursues research topics in atmospheric and oceanic photochemistry, boundary layer and mesoscale meteorology, and biogeochemical trace gas fluxes. 

Yufang Jin

Professor Jin’s research interest in air quality is focused on wildfire emissions. She uses remote sensing techniques to improve the estimates of burned area, fuel loading, tree mortality, and combustion completeness, and thus reduce the uncertainties in fire emission estimate. Her group also performs landscape scale analysis to assess the effectiveness of forest management practices in fire hazard reduction. Her recent projects include a) building statistical models to simulate the interactions between fire, weather, fuels, and other human and environmental drivers; b) predicting future fire distributions in a changing climate under various management scenarios; and c) evaluating subsequent impacts on air quality and human health.

Michael Kleeman

Professor Kleeman's research is focused on the study of urban and regional air quality problems with an emphasis on the size and composition of atmospheric particles and gas-to-particle conversion processes. He uses a combination of measurements and model development to study new features of air pollution and their health effects.  Several recent studies have focused on ultrafine particles (Dp < 0.1 microns) - composition, sources, and population exposure. Professor Kleeman's research group collected ultrafine particle samples at multiple locations across California, analyzed their chemical composition, identified suitable chemical fingerprints, and quantified source contributions. His group then constructed a mathematical model of ultrafine particles for the entire state of California and compared predictions from that model to measurements at monitoring sites. Professor Kleeman has worked on a wide variety of problems including emissions characterization from major sources, atmospheric formation of secondary organic aerosol, health effects of aerosol exposure, agricultural contributions to air pollution, and climate effects on air pollution. On the experimental side, his group has developed novel techniques for organic and inorganic characterization of airborne particles. On the modeling side, Professor Kleeman was the first to perform source apportionment calculations for secondary pollutants inside regional chemical transport models.

Tran Nguyen

Professor Nguyen’s research focuses on the mechanisms of atmospheric oxidation and the composition-linked properties of organic aerosol particles. Atmospheric chemistry experiments in the group are conducted in large atmospheric chambers and in the ambient environment. Her group utilizes custom mass spectrometry tools to speciate and measure oxygenated volatiles and organic aerosol constituents.

Kyaw Tha Paw U

Professor Paw U studies the microscale processes near the ground and around plant canopies. His interests in air quality are focused on large aerosol physics and gas phase transport, emissions, and sinks, including measurements and modeling. Recent projects include estimating turbulent parameters and dispersion coefficients for a California regional air quality study, and determining by eddy-covariance the carbon exchange between the atmosphere and a 500-year old, 65 m high forest. His research group is measuring carbon dioxide fluxes, and is in collaboration with a group measuring biogenic hydrocarbon emissions from the forest canopy. Past projects have included fast-response eddy-covariance measurements of ozone exchange with grasslands. He and his graduate students have also developed the Advanced Canopy-Atmosphere Simulation Algorithm (ACASA), based on higher-order closure principles for turbulent transport. ACASA has been linked to the regional scale model MM5 and can provide regional scale estimates of carbon, water, other gaseous and particulate emissions, transport, and deposition.

Anthony Wexler

Professor Wexler employs theoretical, mathematical modeling, and experimental techniques to explore the role of aerosol particles in global climate, urban smog and human health. Experimental techniques include development and deployment of new instruments for sizing and analyzing individual particles. Mathematical modeling techniques include simulation of particle transport and deposition in human airways, and their transport and transformation in urban and regional smog. He employs both theoretical and experimental techniques to investigate new particle formation by homogeneous nucleation in the marine boundary layer. Dr. Wexler is in the departments of Mechanical and Aeronautical Engineering, Land, Air and Water Resources, and Civil and Environmental Engineering.

Qi Zhang

Professor Zhang conducts field measurements and laboratory studies with a main goal to understand the chemical and physical properties, sources, and lifecycle processes of aerosol particles and fog/cloud droplets in the atmosphere. We also perform integrated analyses of worldwide aerosol mass spectrometry datasets to improve understanding and modeling of aerosol chemistry and climatology. In addition, we develop instruments and data analysis techniques to study the chemistry of organics in airborne PM and droplets.