Production and usage of organophosphate esters (OPEs) as primary substitutes for brominated flame retardants have surged in recent decades and exacerbated health risks in both indoor and outdoor environments. This study systematically explores the geospatial distribution, dynamic indoor-outdoor exchange fluxes, and health risks of the OPEs in China by a novel model framework combining an atmospheric transport model and an indoor exposure model. The results indicate that coastal urban clusters in Eastern and Southern China, characterized by intensive industrial activities and high population density, are core areas of OPE contamination by both indoor and outdoor sources with total outdoor concentration of five major OPE homologues peaked above 240 ng/m3 in 2019. Indoor-outdoor OPE transport exhibits significant spatial heterogeneity in urban areas, revealing strong contribution of indoor OPE pollution to its outdoor contamination in Northern China and weak contribution in Southern China, driven by indoor and outdoor emissions and levels, physical-chemical properties, and climate conditions determining the frequency of ventilation and open architectural designs.
Mao et al. (Tue,) studied this question.