In South Korea, the following are found from data available for the last approx. 100 years: The occurrence frequency of kosa in the period from the latter half of 1930s to the first half of 1940s was almost the same level or more than that in the period after the latter half of 1990s, the frequency was in a decreasing trend in around the period from the latter half of 1940s to 1950s, and it has been in an increasing trend thereafter, with the occurrence of kosa increasing in the season from the late autumn to the early spring.
韓国では、過去約100年間のデータから、1930年代後半から1940年代前半にかけて、黄砂の発生頻度が1990年代後半以降と同程度かそれ以上であったこと、1940年代後半から1950年代頃までは減少傾向で、それ以降増加傾向であり、晩秋から早春にかけての発生頻度が増えている。