Road vehicles make important contributions to a wide range of pollutant emissions from the street level to global scales. The quantification of emissions from road vehicles is, however, highly challenging given the number of individual sources involved and the myriad factors that influence emissions such as fuel type, emission standard, and driving behavior. In this work, we use highly detailed and comprehensive vehicle emission remote sensing measurements made under real driving conditions to develop new bottom-up inventories that can be compared to official national inventory totals. We find that the total UK passenger car and light-duty van emissions of nitrogen oxides (NOx) are underestimated by 24-32%, and up to 47% in urban areas, compared with the UK national inventory, despite agreement within 1.5% for total fuel used. Emissions of NOx at a country level are also shown to vary considerably depending on the mix of vehicle manufacturers in the fleet. Adopting the on-road mix of vehicle manufacturers for six European countries results in up to a 13.4% range in total emissions of NOx. Accounting for the manufacturer-specific fleets at a country level could have a significant impact on emission estimates of NOx and other pollutants across the European countries, which are not currently reflected in emission inventories.
Bibliographical noteFunding Information:
The authors thank Dr Gary Bishop from the University of Denver for access to and use of the FEAT instrument. The support from the UK Met Office DUKEMS project (DN424761 CR19-3 UK Emissions Modeling System) is gratefully acknowledged. Jack Davison was supported by NERC grant NE/S012044/1. We thank Adam Vaughan, Stuart Young, and Will Drysdale from the University of York for the collection of data using the FEAT instrument. Ricardo Energy & Environment’s remote sensing field team, especially Ben Fowler, Tom Green, and Les Phelps are thanked for collecting data using the Opus RSD 5000.
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