Description of Columns in Data_paper Dataset This file provides an explanation of the columns included in the dataset titled Data_paper. It should be noted that emission factors (EFs) and VSP values are given to two significant figures. Ą Vehicle: A unique identifier for each measured vehicle. To comply with GDPR regulations, all vehicles have been anonymised; only technical information is retained. Ą The number of repeats: The number of valid measurement instances recorded for the given record. Ą Repeat: Repeat number for the cases with more than one measurements. Ą Euro: The emission standard category assigned to the vehicle by the manufacturer (e.g., Euro 3, Euro 4). Ą Year: The year in which the vehicle was first registered. Ą VSP (Vehicle Specific Power) (kWh/ton): A calculated metric based on vehicle speed and acceleration. VSP is widely used as an indicator of real-world vehicle emissions. Ą NOx EF (g/km): Real-world distance-based emission factor for nitrogen oxides (NOx), expressed in grams per kilometre. Ą NO2 EF (g/km): Real-world distance-based emission factor for nitrogen dioxide (NO2), in grams per kilometre. Ą NO EF (g/km): Real-world distance-based emission factor for nitric oxide (NO), in grams per kilometre. Ą CO EF (g/km): Real-world distance-based emission factor for carbon monoxide (CO), in grams per kilometre. Ą NO EF (g/kg fuel): Real-world fuel-based emission factor for nitric oxide (NO), in grams per kilogram of fuel burned. Ą NO2 EF (g/kg fuel): Real-world fuel-based emission factor for nitrogen dioxide (NO2), in grams per kilogram of fuel burned. Ą CO EF (g/kg fuel): Real-world fuel-based emission factor for carbon monoxide (CO), in grams per kilogram of fuel burned. Ą PM EF (g/kg fuel): Real-world fuel-based emission factor for particulate matter (PM), in grams per kilogram of fuel burned. Ą Observation: The number of valid measurement instances recorded for the given record. Ą Price (GBP): The estimated retail price of the vehicle in Great Britain Pounds, Ł. Note1. Negative values in the measured emission factors occur when the concentration of a pollutant in the vehicle’s exhaust plume is lower than that of the surrounding ambient air. This indicates that the vehicle’s emissions control system is effectively removing pollutants from the air, an outcome that, while currently uncommon, is expected to become more prevalent as emission standards tighten. Such observations have been reported in nearly all studies employing vehicle emission remote sensing systems, see for example: Bernard, Y., Tietge, U., German, J. and Muncrief, R., 2018. Determination of real-world emissions from passenger vehicles using remote sensing data. The Real Urban Emissions Initiative: London, UK. and HUANG, Y., ORGAN, B., ZHOU, J. L., SURAWSKI, N. C., HONG, G., CHAN, E. F. C. & YAM, Y. S. 2018. Remote sensing of on-road vehicle emissions: Mechanism, applications and a case study from Hong Kong. Atmospheric Environment, 182, 58-74. Note2. Negative Vehicle Specific Power (VSP) values occur when a vehicle is decelerating or coasting, such as during braking or going downhill. These values are normal in emission datasets and represent periods of low or near-zero engine load and emissions. For more information, the reader is invited to see Jiménez-Palacios, J.L. (1999) ‘Evaluation of vehicle power demand and exhaust emissions using an instantaneous fuel consumption model’, Transportation Research Part D: Transport and Environment, 4(3), pp. 193–217. https://doi.org/10.1016/S1361-9209(99)00004-8.