Organophosphate esters in vehicle interior dust from Chinese urban areas: What are the influencing factors of the occurrence?

Organophosphate esters (OPEs) are a class of semi-volatile organic compounds frequently used to various products as flame retardants and plasticizers. As emerging pollutants, OPEs have attracted significant attention due to their potential impacts on human health and ecosystems. This study investigated the occurrence of OPEs in vehicle interior dust across 36 cities in China. The primary aims were to explore the correlations among OPE pollutants, identify potential emission sources, and examine the key factors influencing their distribution. The OPE concentrations ranged from 5450 ng/g to 63,700 ng/g, with the content of three categories of OPEs as follows: ΣChlorinated-OPEs (median: 17420 ng/g) > ΣAlkyl-OPEs (median: 3880 ng/g) > ΣAryl-OPEs (median: 1490 ng/g). In northern China, the aggregate concentration of OPEs in vehicle interior dust demonstrated higher levels compared to those in the western and mid-southeastern region, with the later two appeared to be comparable to each other. Coastal and inland cities displayed variations in OPE levels, with different representative OPEs. The occurrence of OPEs in vehicle interior dust was closely associated with regional economic development levels, motor vehicle parc, and road density. In contrast to other urban areas, first-tier cities showed the highest aggregate levels of OPEs in vehicle interior dust, with a significant increase observed specifically in the concentrations of Alkyl-OPEs and Aryl-OPEs.