ACOM Seminar: Wintertime ammonium nitrate aerosol pollution in urban areas: NOx and VOC control as mitigation strategies


Title: Wintertime ammonium nitrate aerosol pollution in urban areas: NOx and VOC control as mitigation strategies

Presenter: Caroline Womack, NOAA ESRL Chemical Sciences Division, Cooperative Institute for Research in Environmental Sciences, CU Boulder

Abstract: Wintertime particulate matter (PM2.5) pollution is a significant air quality issue in many areas of the world. In several areas in the western US, wintertime PM2.5 exceedances are frequent and often have large contributions from ammonium nitrate aerosol, formed from gas phase reactions of NOx, VOCs, and NH3. Using observations from the recent Utah Winter Fine Particulate Study in the Salt Lake Valley, we modeled the growth of ammonium nitrate aerosol using the parameter Ox,total, which describes both O3 production and HNO3 production, and demonstrates that the two are closely linked. We show that the traditional NOx-VOC framework for evaluating ozone mitigation strategies also applies to ammonium nitrate. Despite being nitrate-limited, ammonium nitrate aerosol pollution in Salt Lake City is responsive to VOC control and, counter-intuitively, not initially responsive to NOx control. We demonstrate simultaneous nitrate limitation and NOx saturation and suggest this phenomenon may be general. This finding may identify an unrecognized control strategy to address a global public health issue in regions with severe winter aerosol pollution.

Monday, February 11, 2019, 3:30 p.m Refreshments 3:15 p.m NCAR Foothills Laboratory FL2-1022 Live webcast:


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Announcement Timing: 
Monday, February 4, 2019 to Monday, February 11, 2019
Calendar Timing: 
Monday, February 11, 2019 - 3:30pm to 4:30pm

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