Emission inventory of heavy metals from on-road vehicles in Xiamen, China, from 2015 to 2060

Abstract

Reducing vehicle emissions to improve air quality has been widely adopted by policy makers. However, insufficient attention has been paid to non-exhaust particulate matter (PM) and the associated heavy metals (HMs) from on-road vehicles, which can cause adverse health effects. In this study, emission inventories of PM2.5 and PM10 and the associated HMs from on-road vehicles in Xiamen, China, were established from 2015 to 2060 under a business-as-usual scenario. In the base year 2021, the total emissions of HMs associated with primary PM2.5 and PM10 were 1.88 × 104 kg and 3.96 × 104 kg, respectively, with the dominant contributions from brake wear and road surface wear. The emissions of HMs were overwhelmingly dominated by light-duty passenger cars and heavy-duty trucks. Fe, Ba, Zn, Cu, Mn, and Ti together accounted for about 97% of the total HMs. High-density emission areas were concentrated in urban centers. From 2015 to 2060, an increasing trend in total HMs emissions was observed due to the superimposed effect of decreasing diesel exhaust and increasing non-exhaust brake wear and road wear. However, the trends of the individual HMs were different from each other. The U-shaped distribution patterns of the relative cancer and non-cancer risks of HMs were observed between 2015 and 2060. Vehicle electrification alone is not enough to effectively reduce the potential health risk of vehicle-related HMs in the future. Reducing HMs from brake wear should be encouraged to use in electric vehicle. Uncertainties in the emissions of HMs were quantified using the Monte Carlo simulation.