Using the case of Ulaanbaatar, Erdenet, and Darkhan cities from Mongolia, the study aimed to assess the contamination level and health risk assessment of heavy metals (As, Cr, Pb, Ni, and Zn) in urban soil. A total of 78 samples was collected from a variety of functional areas. The geoaccumulation index (Igeo) and integrated pollution index (IPI) were used in pollution assessment, while the health risk was scored using a hazard quotient (HQ) and health index (HI) for non-carcinogenic heavy metals, as well as a lifetime average daily dose (LADD) for carcinogenic heavy metals. The results show that the concentration of heavy metals in the soil samples taken from Darkhan city, which presented “uncontaminated” values in terms of Igeo for all metals, was relatively lower than other cities within the contamination assessment. Furthermore, the Igeo value signified “uncontimated to heavily contaminated” soil in the Ulaanbaatar and Erdenet cities. Typically, as for the IPI that observed similar trends with Igeo, the mean IPI values in Ulaanbaatar, Erdenet, and Darkhan were 1.33 (moderate level of pollution), 1.83 (moderate level of pollution), and 0.94 (low level of pollution), respectively. In terms of the assessment of potential health risk, there was a particular or different level of ingestion, dermal contact, and inhalation exposure pathway for human health. Among these three different pathways, the ingestion was estimated by the main contributor for health risk. Each value of HQ and HI indicated that soil heavy metals of studied cities were at a safe level (<1) or had the absence of a significant health risk there. In addition, the potential health risk for children was greater than for adults, where heavy metal values of HI for children had a high value compared to adults. We estimated carcinogenic risks through the inhalation exposure, and as a result, there were no significant risks for human health in the studied cities from three elements (As, Cr, and Ni).

The aim of the present study was to evaluate human health and potential ecological risk assessment in the ger district of Ulaanbaatar city, Mongolia. To perform these risk assessments, soil samples were collected based on reference studies that investigated heavy element distribution in soil samples near the ger area in Ulaanbaatar city. In total, 42 soil samples were collected and 26 heavy metals were identified by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) methods. The measurement results were compared with the reference data in order to validate the soil contamination level. Although there was a large difference between the measurement results of the present and reference data, the general tendency was similar. Soil contamination was assessed by pollution indexes such as geoaccumulation index and enrichment factor. Mo and As were the most enriched elements compared with the other elements. The carcinogenic and noncarcinogenic risks to children exceeded the permissible limits, and for adults, only 12 out of 42 sampling points exceeded the permissible limit of noncarcinogenic effects. According to the results of the ecological risk assessment, Zn and Pb showed from moderate to considerable contamination indexes and high toxicity values for ecological risk of a single element. The Cr and As ranged as very high ecological risk than that of the other measured heavy metals.

The capital city in Mongolia comprises two types of dwellings: apartments and Gers. The Ger is a traditional Mongolian house. Residents of Ger districts in Ulaanbaatar use coal as a source of fuel for daily activities such as heating and cooking in winter due to lack of central heating systems. After coal burning, the ash deposited at the bottom of the oven converts into a powder containing heavy metals that are toxic to human health. Through questionnaires at sites where concentrations of heavy elements were identified in our previous study, we examined the heavy metal exposure pathways of coal ash, which has potentially adverse effects on the health and quality of life of Ger district residents. Survey results indicate that residents have to store the coal ash in packing bags and metal garbage cans near their household fences for at least two weeks because of poor waste management. Owing to the weak seals of the packaging material and open metal cans that contain the coal ash, it is easily transported into surrounding areas by the wind. Adults come into contact with contaminated soil when they are cleaning areas outside and inside the fences, and children are exposed when they play outside the fences. Such activities enhance the dermal exposure as well as inhalation and ingestion pathways of the contaminants for adults and children.