Annual air pollution level of major primary pollutants in Greater Area of Bucharest

In the international context of incomplete information on air pollution in East Europe, we made a review–image of the air pollution problem in Bucharest metropolitan area, Romania, by assessing concentrations, variability, and compliance with the EU regulations of the primary pollutant levels (PM10, PM2.5, SO2, CO, and NOx) from eight sampling stations for six years of continuous sampling (2005–2010) and analyzing for factors affecting the seasonal and spatial variations of PM levels. Investigation of temporal and spatial variation of PM10 and PM2.5 concentrations, as well as their relationships with the measured gaseous air pollutants and with meteorological variables includes correlation analysis, trend analysis, multiple linear regression analysis, and atmospheric back–trajectory analysis. Starting with systematic exceedances of the limit values in 2005 for PM10 and NOx, we observed negative trends for all main pollutants at majority of sites. Exception appears in the background levels where no major improvement was seen. SO2 and CO were found in compliance with the EU regulations in 2010, but PM10 and NOx still remain a problem. Over the years, PM2.5 represents a significant fraction (70–80%) of PM10, irrespective the type of monitoring site. PM levels are higher than those registered for other cities over the Western, Central, and Northern Europe. Combustion–related PM10 fraction varies from 73% (cold season) to 59% (warm season) and is higher with 22–26% than in similar polluted area in Southeast Europe. The contributions are site dependent but the background sites experience comparative combustion–related PM10 contributions to that of sites within Bucharest ring. Wind speed and temperature are the main factors that influence the PM levels; atmospheric pressure and humidity play a secondary role. Pollution events in Bucharest area are mainly caused by local anthropogenic emissions and not by advections from long distances.