Adults

Based on the distance of the place of residence from the oil spill site, we defined the area as high and low exposure. The first survey was conducted in both high and low exposure areas, which include the entire Taean County. However, the second and third surveys were conducted only in the high exposure area (coastal area of the four townships), where the residents generally participated in the clean-up activity for a long period. The fourth and fifth surveys were conducted in high and low exposure areas.

Children

The study area included four townships comprising 83 small villages. There were 13 elementary and 4 middle schools. The surveys were conducted four times biennially in elementary and middle school students. Each time, written informed consent was obtained from the participants or their parents with their assent.