In this study PM samples were collected at two semi-residential sites in UB (Figure 1). Population growth, caused mainly by rural to urban migration has led to major increases in the capital city’s air pollution emissions. Much of the population growth has been in the city’s low-income ger (traditional Mongolian residence) districts such as Zuun ail where coal and wood are burned for heat. Specified the long winters, coal use for cooking and heating is widespread and the principal cause of air pollution.

Previous work (from 2008 to 2009) [4] mainly focused on sampling in the same location.

Sampling was done using a “Gent” type stacked filter sampler [5] .

A portable particle analyzer, known as an optical particle counter (OPC, Model 1.108, GRIMM Inc.), specifically designed for PM_2.5 and PM₁₀ ambient air sampling in the present study. Collecting fraction samples of particulate matter in the coarse particles (PM₁₀) and fine particulates (PM_2.5) size have been monitored using the GRIMM sampler.

The research to collect air particulate matter two extract fraction samples has the special work tapes, and fractions uses were collected GENT air pump system for sampling, and polycarbonate filter with 2 mm thick, 8 mm to filter PM_{10 - 2.5} large particles and 0.4 mm hole filtration to filter less than PM_2.5 micron diameter air particulate matter.

At the Zuun Ail and NRC measurement point coarse and fine particle concentrations were collected to provide measurements during the period of September 2012 to August 2013. PM_{10 - 2.5} and PM_2.5 fraction measurement samples determined the amount of PM air pollution in UB. The results are shown in Table 1.

Particulate matter concentrations were found to be extremely high at times with average PM₁₀ concentrations measured at 276.1 µg/m³ and PM_2.5 concentrations measured at 123.5 µg/m³ in the Zuun Ail respectively (the Guidelines recommends 10 µg/m³ for fine, and 20 µg/m³ for coarse).

Fine particle average annual concentration was measured at 123.5 µg/m³ and 117.5 µg/m³. MNS 4585:2007 specified in (25 µg/m³) 4.9 greater than, (50 µg/m³) again 4.7 greater than, WHO Air Quality Guidelines from size (10 µg/m³) 12.35 greater than, 11.75 greater than recommended standard respectively (Table 1).

There is high air pollution from October through May and extremely high air pollution from January through March. Fine particle concentration peaked during the winter (December, January, March). The monthly average concentration of PM₁₀ is relatively higher 576.9 µg/m³ than 549.9 µg/m³. The average concentration of the other months is from January to May. The average monthly maximum in 2012-2013 from June through October had uniformly low concentration levels. Air pollutant concentration at the surface is strongly influenced by the characteristics of the source emission and the meteorological conditions of the atmosphere [6] .

According to Figure 2, depending on the ambient temperature during the cold seasons, air pollution increased from December to March. The PM generated from coal consumption grew and thus caused the incomplete combustion of coal around Zuun Ail households. Also there is high air pollution in March (large particulate matter 294.9 µg/m³). This may be the result of dust as shown in Figure 3.

Three meteorological and 12 hour radio-sound data weather charts were used to characterize the atmospheric conditions in UB during the measurement period of September 2012 to August 2013.

At both Zuun Ail and NRC sites fractions of 20 chemical elements in the ambient air PM_2.5 samples and PM_{10 - 2.5}. Si, Al, Ca, Fe, Ti were found in the soil-derived components, such these are considered as high-grade (Table 2).

Near the NRC site there was fine particulate pollution (PM_2.5) and the samples contained a high level of BC and sulfur (S) and the products of combustion. The combustion was from the small scale stoves and also the smoke from the thermal plant. It shows high concentration levels of elements (Table 2). The results of the samples show there are basic elements Al, Si, Ca, Ti and Fe which constitute soil and these dominate in both fine and coarse particles in the atmosphere. Airborn soil originating from crystal matter is dominated by Al and Si along with Ca, Ti and Fe. However, this is not only caused by the dust from the soil, the wind, but most of these elements are especially fine particles of combustion products that are related to human activities and the fine fraction contains elements. In addition, Na, Mg, P, Mn elements were contained in all the samples and in a mixture of the soil. Ni, Cu, Zn and Pb are also contained in all samples, but heavy elements were detected in the relatively large number of samples and those are usually contained in soil and generate from motors of vehicles, emission of vehicle brake parts, and garbage combustion. There are two distinct coal combustion source types present in the UB combustion characteristics.

Figure 5 is made by EMF analysis using the elemental analysis results in the air samples. Through the analysis of positive matrix factoring, Soil, Combustion-1 (furnace), Combustion-2 (power plant, small size stove, BC), Dust (buildings and roadwork and other) and Vehicles, there are five patterns of pollution sources that have been identified. The average mass contributions of each of the sources to ambient coarse particle concentration are shown in Table 3 and the source profiles are presented in Figure 5.

Table 3 presents the comparison of the estimated average source contribution obtained from EMF analysis for the fine PM using the same chemical composition data sets of all the samples. In the case of fine PM, several differences were noted.

Around the NRC there may have been a lot of pollution from the soil. This profile contains S and BC as well as other soil components [7] . Air pollution related to human activities indicates similar results showing in the two locations. In the location around Zuun Ail and it is surrounding areas, there is re-development of ger districts and new

buildings, and around the location of NRC there is construction in progress. In proximity to this point there are dusty road passes. For the vehicles near the NRC there is an east route and central road of the city that passes on either side (Table 3). The motor vehicle (mixed diesel and gasoline engine exhaust) source profile is characterized by the high BC and S [3] . This source is also mixed with the crustal elements, Mg, Al, Si, and Fe, suggesting the vehicular exhaust is mixed with re-suspended road dust.