My current research interests involve the chemical processes most relevant to the air quality issues in UT and the Intermountain West, and their policy implications for reducing air pollutants in regional and global scale.  The Wasatch Front frequently experiences air quality events defined by significantly elevated levels of O₃ in summer and elevated fine particulate levels in winter months.   My research on atmospheric volatile organic compounds (VOCs), ozone and the chemical processing of nitrogen oxides aims to improve the scientific understanding of these winter fine particulate pollution episodes and summer ozone issues, and characterize the sources of key pollutants in Utah valleys.

Many urban areas in mountainous regions experience high levels of particulate matter less than 2.5 micron in diameter (PM_2.5) in winter months.  The confined topography, high pressure ridge that warms the air above, combined with urban emissions, create an environment that favors buildup of pollutants including PM_2.5 in winter months.  Fine particulate pollution episodes are closely associated with events of atmospheric stagnation, which limits vertical mixing and traps urban emissions for multiple days.  Secondary aerosols including ammonium nitrate and ammonium chloride dominate the total particulate mass during these pollution episodes in Northern Utah valleys.  However the scientific understanding of the chemical processes driving the particulate formation, the oxidant budget and the role of coupling between chemistry and transport during these pollution episodes are not well established.  Therefore, it is essential to study the chemical processes leading to the particulate nitrate formation, atmospheric chemical composition, spatial and vertical distribution and sources of precursors. Specific research  topics include atmospheric chemistry of nitrogen oxides, whose oxidation in the atmosphere leads to the nitric acid and particulate nitrate formation, relative importance of different chemical pathways for the nitric acid formation, atmospheric nighttime chemistry, secondary aerosol formation, influence of volatile organic compounds (VOCs) on oxidant budget and ozone availability during pollution episodes. 

I led a pilot study, Wintertime PM_2.5 Study in Salt Lake Valley,  to investigate the chemical and meteorological processes governing the fine particulate pollution in Salt Lake Valley in winter of 2015-2016 in collaboration with investigators from National Oceanic and Atmospheric Administration in Boulder, CO and local researchers.  The main findings of this study were the key role played by the nighttime and morning chemistry and the interaction between chemistry and mixing.  

This pilot study led to a larger scale Utah Winter Fine Particulate Study (UWFPS), a collaborative effort between the Chemical Sciences Division (CSD) of NOAA, Utah Division of Air Quality (UDAQ), University of Utah, United States Environmental Protection Agency (US EPA), United States Department of Agriculture, Utah State University, University of Toronto, University of Minnesota, University of Washington and BYU. The study took place in January and February 2017 and investigated key atmospheric chemical processes that drive high particulate matter events during wintertime Persistent Cold Air Pools (PCAPs) events in mountain valleys of northern Utah. The study involves detailed atmospheric chemical measurements of trace gases and aerosols from a NOAA twin otter aircraft to characterize the spatial distribution and temporal variation of the most important pollutants. Detailed ground-based measurements were conducted at University of Utah site, Lindon in Utah Valley, Logan and in Smithfield in Cache Valley.  The ground based observations provide continious, detailed measurements of the composition of the air to augment the aircraft study.  Please visit UWFPS site for details:

http://www.esrl.noaa.gov/csd/groups/csd7/measurements/2017uwfps/

https://deq.utah.gov/legacy/programs/air-quality/research/projects/northern-ut-air-polution/winter-fine-particulate-aircraft-study.htm

The final report is publically available.

https://esrl.noaa.gov/csd/groups/csd7/measurements/2017uwfps/UWFPS_Final_Report.pdf