Chromium concentration levels on the Korean peninsula between 1991 and 2006

Concentrations of chromium (Cr) in air were measured at up to 61 monitoring stations in 15 major cities in Korea over a 16-yr period (1991–2006). The results indicated significant differences in the spatial distribution pattern of Cr due to the prominent effects of industrial activities in both highly industrialized areas and large-scale metropolitan areas. A comparison of Cr levels for the entire period showed that the highest mean from a strong industrial area in AS city (21.1 ng m−3) were >6 times higher than the lowest level (3.44 ng m−3) seen in DJ city. As expected, a comparison of the seasonal patterns showed a significant reduction in Cr levels during summer relative to other seasons with a few exceptions. An analysis of the long-term trends of Cr data indicated that the Cr concentrations decreased systematically until the late 90s. However, the patterns of most cites became more complicated afterwards, showing moderate gains in Cr levels. The overall results of this comprehensive study confirm the fact that the status of Cr pollution is clearly discernible not only between cities due to levels of man-made activities but also between periods with changes in environmental conditions.