Air quality in megacities is recognized as the most important environmental problem. Aerosol pollution by combustion emissions is remaining to be uncertain. Measurements of particulate black carbon (BC) were conducted at the urban background site of Meteorological Observatory (MO) MSU during the spring period of 2017 and 2018. BC mass concentrations ranged from 0.1 to 10 μg m–3, on average 1.5±1.3 and 1.1±0.9 µg/m3 , in 2017 and 2018, respectively. Mean BC concentrations displayed significant

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... urnal variations with poorly prominent morning peak and minimum at day time. BC mass concentrations are higher at night time due the shallow boundary layer and intensive diesel traffic which results in trapping of pollutants. Wind speed and direction are found to be important meteorological factors affected BC concentrations. BC pollution rose identifies the North as the direction of the preferable pollution. A negative correlation between BC concentrations and wind speed confirms the pollution accumulation preferably in stable weather days. Relation of BC pollution to a number of agriculture fires is distinguishable by air mass transportation from South and South-Est of Russia and Western Europe. Mean season ВС concentrations at rural and remote sites in different world locations are discussed.