Urban-Rural Inequality in Microplastic Exposure Exacerbates Health Risks for Rural Residents in Northern China

Abstract. Atmospheric microplastics (MPs) and plasticizers are emerging contaminants requiring systematic research on urban-rural exposure inequality. This study examined MPs and plasticizers in PM2.5 across urban-rural and indoor-outdoor environments in Northern China's Guanzhong Plain. The 24 h time-weighted exposure concentrations for MPs and plasticizers were 3.6 and 6.8 times higher, respectively, in rural areas than in urban areas. Polyethylene terephthalate (PET) exhibited the greatest disparity in urban-rural MPs exposure. Plasticizer exposure was overwhelmingly dominated by phthalates, with di(2-ethylhexyl) phthalate (DEHP) reaching exceptionally high concentrations in rural indoor air (≈ 600 ng m-3), far exceeding urban levels (10.4 times). Rural residents experienced consistently higher inhalation exposure to MPs and plasticizers, resulting in substantially elevated health risks, with non-carcinogenic and carcinogenic risks both 6.9 times higher than the urban populations. The volume-normalized oxidative potential (DTTv) was significantly higher in rural than in urban environments (10.8 vs. 1.79 nmol min-1 m-3) and strongly correlated with most MPs and plasticizer species (r > 0.7). Source apportionment revealed that contacting plastic products accounted for 51.7 % of the MPs and plasticizers exposure in rural areas, nearly double the urban value of 27.6 %. In contrast, transportation-related source contributed only 5.9 % in rural areas but 22.6 % in urban areas. These results demonstrate clear urban–rural inequality in MPs and plasticizers exposure and related health effects, highlighting the need for exposure-based and equity-aware assessment frameworks and interventions for air emerging contaminants, especially for disadvantaged rural areas.