You are here:
Sensitivity of Particulate Matter Concentrations to Revised Estimates of Onroad Ammonia Emissions
Citation:
Sonntag, D., J. Bash, C. Toro, G. Burke, B. Murphy, K. Seltzer, H. Simon, S. Benish, K. Foley, A. Eyth, C. Allen, J. Godfrey, M. Shephard, AND K. Cady-Pereira. Sensitivity of Particulate Matter Concentrations to Revised Estimates of Onroad Ammonia Emissions. CMAS, Virtual, Virtual, November 01 - 05, 2021.
Impact/Purpose:
In urban areas, mobile sources are important sources of ammonia (NH3) emissions that contribute to secondary formation of particulate matter. Recent studies have suggested that mobile ammonia emissions are underestimated in national and state emission inventories.[1],[2] In this study, we compared roadside[3],[4] and tunnel[5] ammonia measurements from light-duty gasoline and heavy-duty diesel vehicles to ammonia emission rates from EPA’s latest version of the MOtor Vehicle Emission Simulator (MOVES3). The roadside and tunnel comparisons suggest that the ammonia emission rates for onroad vehicles are underestimated in MOVES3. [1] Sun, K., et al. (2017). Vehicl/e Emissions as an Important Urban Ammonia Source in the United States and China. Environ Sci Technol, 51 (4), 2472-2481. DOI: 10.1021/acs.est.6b02805. [2] Emery, C., et al. (2020). Investigating Sources of Ammonia Uncertainty in Modeling the Salt Lake City PM2.5 Nonattainment Area. Prepared for Utah Division of Air Quality. Prepared by Ramboll US Corporation. May 2020. [3] Bishop, G. A. and D. H. Stedman (2015). Reactive Nitrogen Species Emission Trends in Three Light-/Medium-Duty United States Fleets. Environ Sci Technol, 49 (18), 11234-11240. DOI: 10.1021/acs.est.5b02392. [4] Haugen, M. J., et al. (2018). Evaluation of Heavy- and Medium-Duty On-Road Vehicle Emissions in California’s South Coast Air Basin. Environ Sci Technol, 52 (22), 13298-13305. DOI: 10.1021/acs.est.8b03994. [5] Preble, C. V., et al. (2019). Control Technology-Driven Changes to In-Use Heavy-Duty Diesel Truck Emissions of Nitrogenous Species and Related Environmental Impacts. Environ Sci Technol, 53 (24), 14568-14576. DOI: 10.1021/acs.est.9b04763.
Description:
In urban areas, mobile sources are important sources of ammonia (NH3) emissions that contribute to secondary formation of particulate matter. Recent studies have suggested that mobile ammonia emissions are underestimated in national and state emission inventories.[1],[2] In this study, we compared roadside[3],[4] and tunnel[5] ammonia measurements from light-duty gasoline and heavy-duty diesel vehicles to ammonia emission rates from EPA’s latest version of the MOtor Vehicle Emission Simulator (MOVES3). The roadside and tunnel comparisons suggest that the ammonia emission rates for onroad vehicles are underestimated in MOVES3. From the evaluated roadside and tunnel data, we developed revised MOVES ammonia emission rates by vehicle class, model year, vehicle age, and operating mode for light-duty gasoline and heavy-duty vehicles for use in this study. We explored the effect of the revised onroad ammonia emission rates on US air quality using Community Multiscale Air Quality (CMAQ) simulations for the calendar year 2017 that were performed as part of the EPA’s Air QUAlity TimE Series Project (EQUATES) to develop modeled meteorology, emissions, air quality and pollutant deposition for 2002 through 2017. Modeled datasets covering the Conterminous US (CONUS) were estimated using 12 km horizontal grid spacing, MOVES3 onroad emissions, Weather Research and Forecasting Model (WRFv4.1.1) meteorology, and CMAQv5.3.2 air quality modeling. A sensitivity simulation was performed with ammonia emissions from onroad non-diesel (primarily gasoline) vehicles scaled by a factor of 2.08 and onroad diesel vehicles scaled by a factor of 1.54; the factors were based on national-level MOVES output for calendar year 2017 using MOVES3 and the revised emission rates. All other model inputs and parameters were held constant. We explored the impact of these changes on PM2.5 concentrations. These updates increased three-month average PM2.5 by up to 0.5 ug/m3 in winter with regional impacts spread across the Eastern US and in some Western urban areas. Three-month average PM2.5 concentrations increased by up to 0.2 ug/m3 in summer with changes focused in major urban areas. [1] Sun, K., et al. (2017). Vehicle Emissions as an Important Urban Ammonia Source in the United States and China. Environ Sci Technol, 51 (4), 2472-2481. DOI: 10.1021/acs.est.6b02805. [2] Emery, C., et al. (2020). Investigating Sources of Ammonia Uncertainty in Modeling the Salt Lake City PM2.5 Nonattainment Area. Prepared for Utah Division of Air Quality. Prepared by Ramboll US Corporation. May 2020. [3] Bishop, G. A. and D. H. Stedman (2015). Reactive Nitrogen Species Emission Trends in Three Light-/Medium-Duty United States Fleets. Environ Sci Technol, 49 (18), 11234-11240. DOI: 10.1021/acs.est.5b02392. [4] Haugen, M. J., et al. (2018). Evaluation of Heavy- and Medium-Duty On-Road Vehicle Emissions in California’s South Coast Air Basin. Environ Sci Technol, 52 (22), 13298-13305. DOI: 10.1021/acs.est.8b03994. [5] Preble, C. V., et al. (2019). Control Technology-Driven Changes to In-Use Heavy-Duty Diesel Truck Emissions of Nitrogenous Species and Related Environmental Impacts. Environ Sci Technol, 53 (24), 14568-14576. DOI: 10.1021/acs.est.9b04763.