The US Environmental Protection Agency (EPA) estimates on-road vehicles emissions using the Motor Vehicle Emission Simulator (MOVES). We developed updated ammonia emission rates for MOVES based on road-side exhaust emission measurements of light-duty gasoline and heavy-duty diesel vehicles. The resulting nationwide on-road vehicle ammonia emissions are 1.8, 2.1, 1.8, and 1.6 times higher than the MOVES3 estimates for calendar years 2010, 2017, 2024, and 2035, respectively, primarily due to an increase in light-duty gasoline vehicle NH emission rates. We conducted an air quality simulation using the Community Multi-Scale Air Quality (CMAQv5.3.2) model to evaluate the sensitivity of modeled ammonia and fine particulate matter (PM) concentrations in calendar year 2017 using the updated on-road vehicle ammonia emissions. The average monthly urban ammonia ambient concentrations increased by up to 2.3 ppb in January and 3.0 ppb in July. The updated on-road NH emission rates resulted in better agreement of modeled ammonia concentrations with 2017 annual average ambient ammonia measurements, reducing model bias by 5.8 % in the Northeast region. Modeled average winter PM concentrations increased in urban areas, including enhancements of up to 0.5 μg/m in the northeast United States. The updated ammonia emission rates have been incorporated in MOVES4 and will be used in future versions of the NEI and EPA's modeling platforms.

中文翻译：

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美国空气质量对汽车氨排放的敏感性

美国环境保护署 (EPA) 使用机动车辆排放模拟器 (MOVES) 估算道路车辆排放量。我们根据轻型汽油车和重型柴油车的路边废气排放测量，制定了 MOVES 的最新氨排放率。由此得出的全国道路车辆氨排放量分别比 MOVES3 2010、2017、2024 和 2035 年估计值高 1.8、2.1、1.8 和 1.6 倍，主要是由于轻型汽油车氨排放量的增加排放率。我们使用社区多尺度空气质量 (CMAQv5.3.2) 模型进行了空气质量模拟，以使用更新的道路车辆氨排放量来评估 2017 日历年模拟氨和细颗粒物 (PM) 浓度的敏感性。 1 月份城市氨环境月平均浓度增加了 2.3 ppb，7 月份增加了 3.0 ppb。更新后的道路 NH 排放率使模拟的氨浓度与 2017 年平均环境氨测量值更加一致，将东北地区的模型偏差减少了 5.8%。模拟的城市地区冬季 PM 平均浓度有所增加，其中美国东北部的浓度增加了 0.5 微克/立方米。更新后的氨排放率已纳入 MOVES4 中，并将用于 NEI 和 EPA 建模平台的未来版本。