Vehicle Emissions as an Important Urban Ammonia Source in the United States and China

Kang Sun, Lei Tao, David J. Miller, Da Pan, Levi M. Golston, Mark Andrew Zondlo, Robert J. Griffin, H. W. Wallace, Yu Jun Leong, M. Melissa Yang, Yan Zhang, Denise Leonore Mauzerall, Tong Zhu

Research output: Contribution to journalArticlepeer-review

203 Scopus citations


Ammoniated aerosols are important for urban air quality, but emissions of the key precursor NH3 are not well quantified. Mobile laboratory observations are used to characterize fleet-integrated NH3 emissions in six cities in the U.S. and China. Vehicle NH3:CO2 emission ratios in the U.S. are similar between cities (0.33-0.40 ppbv/ppmv, 15% uncertainty) despite differences in fleet composition, climate, and fuel composition. While Beijing, China has a comparable emission ratio (0.36 ppbv/ppmv) to the U.S. cities, less developed Chinese cities show higher emission ratios (0.44 and 0.55 ppbv/ppmv). If the vehicle CO2 inventories are accurate, NH3 emissions from U.S. vehicles (0.26 ± 0.07 Tg/yr) are more than twice those of the National Emission Inventory (0.12 Tg/yr), while Chinese NH3 vehicle emissions (0.09 ± 0.02 Tg/yr) are similar to a bottom-up inventory. Vehicle NH3 emissions are greater than agricultural emissions in counties containing near half of the U.S. population and require reconsideration in urban air quality models due to their colocation with other aerosol precursors and the uncertainties regarding NH3 losses from upwind agricultural sources. Ammonia emissions in developing cities are especially important because of their high emission ratios and rapid motorizations. (Chemical Equation Presented).

Original languageEnglish (US)
Pages (from-to)2472-2481
Number of pages10
JournalEnvironmental Science and Technology
Issue number4
StatePublished - Feb 21 2017

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Environmental Chemistry


Dive into the research topics of 'Vehicle Emissions as an Important Urban Ammonia Source in the United States and China'. Together they form a unique fingerprint.

Cite this