Statistical analysis of the seasonal and regional characteristics of PM(particulate matter) and Gas species concentration in urban Gwangju and National background sites, Korea (2015-2017) The aim of this study is to investigate the simply and meaningful statistical results with only particulate matter (PM), gas species (O3, NO2, SO2, and CO) and meteorological data from four sites (three national background sites and one urban site), which are Baengnyeong-do, Jeju-Island, Ulleung-do, and urban Gwangju, in 2015 to 2017, Korea. Specifying the characteristics of seasonal and regional PM and gas concentrations is an important factor at national level. This is because it functions as a reference material for evaluating the national PM mass concentration. Nowadays, statistical analysis is essential. Therefore, a better and clear seasonal and regional characteristics analysis for PM have to be conducted. In this study, seasonal and regional characteristics were examined for four regions during 2015-2017 using ANOVA, correlation, and k-means clustering analysis. As a result, characteristics of urban Gwangju areas and national background sites were somewhat different, and the occurrence of PM events considered to be the long-ranged transported effect in spring and winter could be distinguished.