## 3 Results and Discussion
### Human Health Risks Assessment  
The assessment of Hazard Quotients (HQ), Hazard Indexes (HI), and Total Hazard Indexes (THI) for adults revealed all values are below 1 (Figure 3a-c). This indicates no significant non-carcinogenic health risk from PTEs absorbed via ingestion and inhalation routes in atmospheric deposition in and around IAREEM areas. The ranking of elements by non-carcinogenic risk is Pb \(>\) As \(>\) Cr \(>\) Cd \(>\) Cu \(>\) Ni \(>\) Mo for adults. However, HQingestion values for Pb and As exceed 1 for children in mining regions containing heavy rare earth elements (Figure 3e), suggesting potential adverse health effects from exposure to atmospheric deposition containing Pb and As. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Location** & **Period** & **Landuse** & **As** & **Cd** & **Cr** & **Cu** & **Mo** & **Ni** & **Pb** & **Reference** \\ \hline Ganzhou, China & 2019–2020 & Rare earth mine & 23.64 & 2.85 & 58.24 & 76.68 & 5.67 & 26.43 & 121.04 & This study \\ \hline Wuhai, China & 2018–2019 & Coal mine & 408.78 & 1.97 & 45.97 & 27.40 & & 25.41 & 38.93 & [40] \\ \hline Shanghai, China & 2011–2012 & Rural region & 47.60 & 1.53 & & & & 150.60 & [43] \\ \hline Taihu lake, China & 2016–2018 & Woodland & & 9.42 & 71.60 & 139.60 & & 45.98 & 223.60 & [14] \\ \hline Yinchuang, China & 2019–2020 & Urban & 28.00 & 0.74 & 82.60 & 46.50 & 2.72 & 35.10 & 48.80 & [41] \\ \hline Kandy, Sri Lanka & 2017–2018 & Urban & 10.12 & 68.60 & 103.00 & 123.60 & & 87.60 & 234.40 & [42] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of atmospheric deposition (mg kg\({}^{-1}\)) of metals for concentration between the REE and other regions. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Element \({}^{*}\)** & **Mean** & **Min** & **Max** & **Median** & **Std \({}^{1}\)** & **Skew** & **CV \({}^{2}\)** & **Reference \({}^{3}\)** \\ \hline As & 23.64 & 3.18 & 251.87 & 8.15 & 52.39 & 3.94 & 2.22 & 70.00 \\ Cd & 2.85 & 0.45 & 13.30 & 2.35 & 2.46 & 3.36 & 0.86 & 0.13 \\ Cr & 58.24 & 10.31 & 303.11 & 45.03 & 55.84 & 3.82 & 0.96 & 78.00 \\ Cu & 76.68 & 26.08 & 319.85 & 60.54 & 71.44 & 2.75 & 0.93 & 26.00 \\ Mo & 5.67 & 1.09 & 18.96 & 4.53 & 4.47 & 1.99 & 0.79 & 0.73 \\ Ni & 26.43 & 5.37 & 143.39 & 20.69 & 26.58 & 3.90 & 1.01 & 33.00 \\ Pb & 121.04 & 32.40 & 654.10 & 73.88 & 136.23 & 3.27 & 1.13 & 26.00 \\ \hline \hline \end{tabular} \({}^{*}\) Units are mg kg\({}^{-1}\). \({}^{1}\) Standard deviation, \({}^{2}\) coefficient of variation, \({}^{3}\) the data in references [39].  
\end{table} 
Table 5: Statistical analysis of trace element concentration of atmospheric deposition. Figure 2: The regional distribution of seven potentially toxic elements (PTEs) in atmospheric deposition. Each dot in the legend symbolizes a sampling site. The color of each dot categorizes PTE concentrations into five distinct groups, based on quartile divisions. In terms of carcinogenic risk, the values for CRingestion, CRinhalation, and combined exposure were all below \(1\times 10^{-4}\), indicating that the carcinogenic risk for adults from PTEs in atmospheric deposition is within acceptable limits. Regarding carcinogenic risk, the values for CRingestion, CRinhalation, and CR were less than \(1\times 10^{-4}\) (Figure 4a-d). The ranking of elements by non-carcinogenic risk followed the order of Pb > As > Cr > Cd > Cu > Ni > Mo  
Figure 3: Non-cancer Hazard Quotients (HQ) and Hazard Indexes (HI) of PTEs via ingestion and inhalation exposure pathways calculated for adults (**a–d**) and for children (**e–h**). In detail: (**a**) HQ of each element through ingestion; (**b**) HQ of each element through inhalation; (**c**) HI of each element through ingestion and inhalation; (**d**) HQ and HI of combined elements through ingestion and inhalation. Figure 3e–h is similar to Figure 3a–d. The red dotted line reflects the safety threshold for potential non-carcinogenic risks. Dark solid circles represent outliers. (Figure 4c,g).