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Project Number:
Spatial Mapping of Ozone Formation near San Antonio
Lead PI:
Ezra Wood
Institution(s) Represented:
Drexel University - Ezra Wood
AQRP Project Manager:
Gary McGaughey
TCEQ Project Liaison:
Mark Estes
Awarded Amount:

Ozone (O3) is the main component of smog and causes adverse effects on human health, especially to sensitive groups such as children and the elderly. Unlike "primary" pollutants which are emitted directly from vehicles and industrial processes, ozone is formed in the atmosphere from photochemical reactions involving volatile organic compounds (VOCs) and nitrogen oxides ("NOx"). In order for San Antonio to comply with the new National Ambient Air Quality Standard for ozone of 70 ppb, regulators will need to make science-based decisions on effective mitigation strategies, including emission reduction programs. Such decisions will require knowledge of the amount of ozone that is transported into the city from upwind regions (usually located southeast of San Antonio), the absolute rates of ozone formation in and around San Antonio, the relative importance and interaction of emissions from various sources (e.g., upwind oil and gas activity and urban emissions from the city itself), and when and where ozone formation occurs under "NOx-limited" or "VOC-limited" conditions. In contrast to Houston and Dallas, little is known about ozone formation in San Antonio. This research project will address this major shortcoming and elucidate the mechanisms and rates of ozone formation that affect air quality in San Antonio using novel measurements of peroxy radicals aboard a mobile supersite during a 3-week field project during late spring of 2017. Instantaneous ozone production rates P(O3) will be quantified aboard the Aerodyne Mobile Laboratory using new but tested measurements of total peroxy radicals. These measurements will be used to "map" the rate of ozone formation upwind, downwind, and inside of the urban core of San Antonio. Measurements of organic nitrates will also be used to investigate the role of alkanes and organic nitrate formation as a terminator of ozone chemistry.
The main goals of the project are to quantify how much ozone is produced inside the city compared to upwind, and to quantify the role of alkanes in ozone formation.

Work Plan:
Technical Report(s):
Final Report: