The impacts of BC and PM<sub>2.5</sub> emissions from different source sectors (e.g. transportation, power, industry, residential, and biomass burning) and source regions (e.g. Europe, North America, China, Russia, Central Asia, South Asia, and the Middle East) to Arctic BC and PM<sub>2.5</sub> concentrations are investigated using a series of sensitivity runs with WRF-STEM modeling framework. The simulations are validated using aircraft observations over the Arctic during spring and summer 2008. Emissions from power, industrial, and biomass burning sectors are found to be the main contributors to the Arctic PM<sub>2.5</sub> with contributions of ~ 30 %, ~ 25 %, and ~ 20 % respectively. In contrast, the residential and transportation sectors are identified as the major contributors to Arctic BC with contributions of ~ 38 % and ~ 30 %. Anthropogenic emissions are the most dominant contributors (~ 88 %) to the BC surface concentration over the Arctic; however, the contribution from biomass burning is significant over the summer (up to ~ 50 %). Among all geographical regions, Europe and China have the highest contributions to the BC surface concentrations with contributions of ~ 46 % and ~ 25 % respectively. Further sensitivity runs show that among various economic sectors of all geographic regions, European and Chinese residential sector contribute up to ~ 25 % and ~ 14 % to the Arctic average surface BC concentration. For Arctic PM<sub>2.5</sub>, the anthropogenic emissions contribute >~ 75 % at the surface annually, with contributions of ~ 25 % from Europe and ~ 20 % from China; however, the contributions of biomass burning emissions are significant in particular during spring and summer. The contributions of each geographical region to the Arctic PM<sub>2.5</sub> and BC vary significantly with altitude. The simulations show that the BC from China is transported to the Arctic in the mid-troposphere, while, BC from European emission sources are transported near the surface under 5 km, especially during winter.