Spatial variability and trends in ambient air concentrations of metals in Cracow, Poland.

Even though the air quality has been improving since the beginning of the 1980s, Cracow still belongs to the most polluted cities in Poland. The air pollution originates mainly from industry, small-size emission sources and transport. Metals in ambient air have been monitored since 1992 by 4 stations located within the city. The aim of the study was to determine the city areas where the national limits of heavy metals in suspended particles are exceeded and to assess the trends for the years 1992-1999. The monthly mean and maximum values of lead, zinc, chromium, copper, cadmium, nickel and iron were used in the analysis. Between 1992 and 1999, the level of most monitored metals in suspended particles was much below the national standards. Only the concentration of lead exceeded the limits by 50% in the area with the station monitoring traffic air pollution. However, the substantial variability in concentrations of monitored metals observed within the city was most pronounced around the metallurgical plant. Nowadays a new factor prevails: heavy traffic has resulted in a substantially enhanced concentration of lead across the city.