Inhalation exposure and potential health risk estimation of lanthanides elements in PM 2.5 associated with rare earth mining areas: a case of Baotou city, northern China.

Particulate pollution, especially PM2.5 (particles with an aerodynamic equivalent diameter of 2.5 μm or less), has received increased attention in China recently. In this study, PM2.5 samples were collected in August 2013 and April 2014 from different regions of Baotou, the largest rare earth elements (REEs) processing city in northern China. The concentrations and distribution patterns of REEs in PM2.5 were analyzed, and the inhalation exposure to REEs associated with PM2.5 was assessed. The results showed that the REEs levels were 56.9 and 15.3 ng m-3 in August 2013 and April 2014, respectively. These values are much higher than those in non-REEs mining areas. The distribution patterns of REEs exhibited LREE enrichment. The Eu and Ce anomalies displayed slightly positive and negative values, respectively, which were in accordance with the background soil and ore. The average daily intake amounts of REEs for population through inhalation exposure of PM2.5 in Baotou were in the range of 5.09 × 10-7 to 2.25 × 10-5 mg kg-1 day-1 .