Airborne cadmium in the major monitoring locations in Korea between 1991 and 2004

Air quality monitoring data for cadmium (Cd) collected in 13 cities in Korea over a 14-year period (1991–2004) have been analyzed. In the course of this study, variation of Cd was examined over time and with location to learn about its sources, transport, and removal processes and to help improve air quality control. The results of this study indicate that the spatial distribution of Cd is clearly distinguishable between different cities and that such a pattern is sensitively reflected by such a factor as the level of industrialization. Comparison of the Cd data sets between different cities indicated that its concentration levels observed in highly industrialized cities approached or exceeded 10 ng m−3, while those of urban background cities were found to lie in a narrow range of 1–3 ng m−3. As such, Cd values determined from the polluted areas were notably higher than the relatively clean ones, at least by several times. The Cd data collected from all study sites were also evaluated with respect to temporal behavior. Inspection of seasonal patterns generally showed the occurrences of the highest Cd value during spring (and winter) and the lowest one during summer. When the long-term pattern of Cd was assessed across all study years, the results differed greatly between different cities in relation to their pollution status. Although Cd concentrations tended to decrease rather abruptly in highly industrialized cities, its patterns for most cities were too variable to project a definitive trend. The results of this analysis thus suggest that Cd concentration levels in most urban areas of Korea are fairly comparable with those commonly seen in the urban background areas of western countries. Considering that most urban areas are affected by various pollution sources and that Cd concentrations have been reduced significantly through the years, more deliberate efforts are needed to further control Cd concentrations in the atmosphere.