This paper presents two years (2010-2012) of measurement results for organic (OC) and elemental (EC) carbon obtained at the Siberian background station ZOTTO (61 º N; 89 º E). Overall, the obtained results have shown that in spite of the remoteness of the ZOTTO station from industrial areas, the aerosols of boreal forests contain organic and elemental carbon in quantities that are well above background values. In winter and autumn the high aerosol carbon content arises from long-range transport (~1000 km) of air masses from large cities of South and South-West Siberia. In spring and in summer high levels of contamination are caused by regional forest fires and burning of agricultural land in the steppe zone of the Russian-Kazakh border sector. Background concentrations of carbonaceous particles were observed in no more than 20 % of the whole observation period. In summer season the variations of the background concentrations of organic carbon are closely correlated with air temperature, indicating a biogeni