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Based on the collected urban motor vehicle activity ownership and traffic flow of highways, combined with the mileage and source profiles of VOCs, using the emission factor method, we established high-resolution emission inventories from 2016 to 2019 for urban and 2016-based highway motor vehicles, respectively, in Henan Province, China. The results showed that gasoline vehicles, particularly minibuses and ordinary motorcycles, were the main contributors of CO, VOCs, and NH 3 , whereas heavy-duty and light-duty diesel trucks emitted SO 2 , NO x , and PM. Vehicles with China 1, China 3, and China 4 emission standards contributed significantly to pollutant emissions in the fleet. The temporal variation in traffic flow was consistent with the changes in freight and passenger traffic, with higher coefficients of variation for highways from August to October and the lowest in November. The weekly and daily changes in urban trunk roads showed distinct weekend effects and clear double-peak features, respectively. High-value emission areas were concentrated in urban centers with dense transport networks and high traffic volumes and on roads radiating outward from urban areas. The Lianhuo Expressway and the Beijing-Hong Kong-Macau Expressway were high-emission roads. Light-duty gasoline vehicles made the largest contribution to the ozone formation potential (OFP) of VOCs from motor vehicles. Five species, such as ethylene and propylene, contributed significantly to VOC emissions and OFP. The average annual growth rate of vehicle ownership from 2016 to 2019 was 5.7%. Compared with 2016, VOC emissions increased by 2.8% in 2019, whereas emissions of other pollutants showed decreasing trends of different degrees, with decreases of 76.3%, 51.7%, 50.3%, 43.1%, 16.7%, and 5.9% for SO 2 , PM 2.5 , PM 10 , NH 3 , CO, and NO x , respectively. The emission reduction percentage of each pollutant in 2019 under the control policies relative to the baseline scenario ranged from 15.6% to 82.4%.

Based on the best available activity data at a city level from top down and bottom up methods, a 2013-based emission inventory of NH 3 was established for the Henan Province using an emission factors method. The 3 km×3 km spatial gridded distribution was carried out by using GIS technology. The results showed that the total amount of atmospheric NH 3 emission in Henan Province in 2013 was 1035.3 kt, and the average emission intensity reached levels of 6.4 t/km 2 . Livestock and nitrogen fertilizer applications were the top two emission sources, accounting for 52.71% and 31.53% of the total emissions, respectively. Beef, laying hen, and goats were the main contributors in the livestock category, accounting for 34.98%, 16.63%, and 14.02% of the total emissions, respectively. There were different characteristics between emission source contributions and emission intensities in each city. Nanyang, Zhoukou, Shangqiu, and Zhumadian were the prefecture-level cities with large emissions, accounting for 11.53%, 9.84%, 9.62%, and 9.57% of the total amount in Henan Province, respectively. The NH 3 emission intensities of Puyang and Louhe were larger than those of other cities, reaching up to 10.7 t·km -2 and 10.2 t·km -2 , respectively. The spatial distribution revealed that emissions in the middle eastern region were relatively higher; whereas, the western region emissions were relatively low. The areas with high emissions were concentrated in the plains and densely populated areas.