Fig. 1: Pollution generated per kilometre by used vehicle fleets.

a–c, Exported cars (orange) generate at least 13–24% more CO₂ per kilometre (a), similar average but (through overdispersion) higher median fine particulate matter pollution (b) and at least 53% more nitrogen oxides per kilometre than scrapped (green) or on-road (blue) vehicle fleets (c). d–f, Both exported car and light goods vehicle (LGV) fleets also have larger observed engine capacities (d) and worse fuel efficiency (e) despite being similar ages to on-road fleets and much younger than contemporary scrapped vehicles (f). Boxes show IQRs, whiskers are 1.5× IQR, sample size (millions) shown on upper x axes, summary data supplied in a Figshare repository²⁵.