Abstract
Particulate matter (PM) air pollution in the urban environment is mainly related to the presence of potential sources throughout the year. Road transport is one of the most important sources of PM in the urban environment, because it directly affects pedestrians. PM measurements were performed in the city of Žilina, Slovakia, at various road-traffic-related measurement stations over the course of several years. This paper evaluates changes in the concentration of the fine fraction (PM(2.5)), the ultrafine fraction (PM(1)), and the coarse fraction (PM(2.5-10)) over time. PM concentrations were measured by reference gravimetric method. Significant changes in PM concentrations over time due to the diversification of pollution sources and other, secondary factors can be observed from the analysis of the measured data. PM samples were subjected to chemical analysis inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of elements (Mg, Al, Ca, Cr, Cu, Fe, Cd, Sb, Ba, Pb, Ni, and Zn). The seasonal variation of elements was evaluated, and the sources of PM(2.5), PM(1), and PM(2.5-10) were estimated using principal component analysis (PCA) and positive matrix factorization (PMF). PM(2.5) (maximum concentration of 148.95 µg/m(3) over 24 h) and PM(1) (maximum concentration of 110.51 µg/m(3) over 24 h) showed the highest concentrations during the heating season, together with the elements Cd, Pb, and Zn, which showed a significant presence in these fractions. On the other hand, PM(2.5-10) (maximum concentration of 38.17 µg/m(3) over 24 h) was significantly related to the elements Cu, Sb, Ba, Ca, Cr, Fe, Mg, and Al. High correlation coefficients (r ≥ 0.8) were found for the elements Mg, Ca, Fe, Al, Cd, Pb, and Zn in the PM(1) fraction, Cd, Pb, and Zn in PM(2.5), and Ba, Sb, Fe, Cu, Cr, Mg, Al, and Ca in PM(2.5-10). Using PMF analysis, three major sources of PM (abrasion from tires and brakes, road dust resuspension/winter salting, and combustion processes) were identified for the PM(2.5) and PM(1) fractions, as well as for the coarse PM(2.5-10) fraction. This study reveals the importance of non-exhaust PM emissions in the urban environment.