Long-term trend of NO2 in major urban areas of Korea and possible consequences for health

- Long-term variations of NO2 are investigated using the data from seven major urban areas in Korea.
- The pollution status of NO2 is explored in association with dynamic changes in environmental conditions.
- The observed reductions after 2000 reflect the direct effects of implementation of administrative efforts.

Long-term trend of the atmospheric NO2 was analyzed using ambient monitoring data collected from seven major cities in Korea over two decades (1989-2010). In light of the notable environmental policies initiated since June 2000, these NO2 data were also evaluated after dividing the entire study period into period I (1989-1999) and period II (2000-2010). Accordingly, the mean concentrations of NO2 in five out of seven cities in period II were higher by 1-26% than period I. This recognizable increase in period II is likely to reflect the effect of increasing consumption rates in primary energy (e.g., petroleum and LNG). An examination of the seasonal trend of NO2 consistently indicates the highest concentrations occurred during winter because of the combined effects of the anthropogenic emission and meteorological conditions. A health risk assessment of our data indicated that the NO2 exposure (to adults, children, and infants) increased from period I to period II. Also, the long-term trends of NO2 were analyzed based on the seasonal Mann-Kendall test and the Sen's slopes. It revealed that NO2 levels of most cities had the linearly increasing trends during period I. However, decreasing trends appeared during period II to reflect the direct effect of implementation of administrative efforts including the fuel switching control policy.