Onsan-eup
Onsan-eup belongs to Ulju-gun, Ulju-gun, Korea. Onsan-eup is located in Onsan Industrial Park, which has heavy chemical industrial parks and non-ferrous metal companies. Due to the industrial complex, the concentration of pollutants such as SO2, NO2, O3, CO and PM10 was higher than other areas in this area, and since March 18, 1986, is. According to Choi Bong-wook and his colleagues, the highest concentrations of pollutants were found in Ulsan and Onsan areas, especially in Wonsan.