Asian Dust

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Asian Dust (also yellow dust, or yellow sand) is a seasonal meteorological phenomenon which affects much of East Asia sporadically during the springtime months. The dust originates in the deserts of Mongolia and northern China where high-speed surface winds and intense dust storms kick up dense clouds of fine, dry soil particles. These clouds are then carried eastward by prevailing winds and pass over China, North and South Korea, and Japan. Sometimes, the airborne particulates are carried much further, in significant concentrations which affect air quality as far east as the United States. Areas affected by the dust experience decreased visibility and the dust is known to cause health problems, such as sore throat and respiratory difficulties, in residents. The dust has been shown to increase the daily mortality rate in one affected region by 1.7%. The effects of the dust are not, however, strictly negative, as it is thought to enrich the soil of the regions where it is eventually deposited by contributing important trace minerals.

The dust is caused by desertification in northern China near the Gobi Desert. Although such storms have occurred from time to time throughout history, they became a pronounced problem in the latter half of the 20th century, as agricultural pressures on the Gobi region intensified.

In recent years, South Korea and the People's Republic of China have participated in reforestation efforts in the source region. However, this has not affected the problem in any significant way. In April 2006, South Korean meteorologists reported the worst yellow dust storm in four years. ^[1]

1 Local names
2 Composition
3 Historical reports
4 See also
5 External links

[edit] Local names

Asian dust is known locally by various names, each of which means "yellow dust" or "yellow sand":

"Hwang-sa" (황사, 黃沙/黃砂) in Korean
"Huangsha" （黄砂）in Chinese
"Kousa" (黄砂) in Japanese

[edit] Composition

An analysis of Asian Dust clouds conducted in China in 2001 showed them to contain high concentrations of silicon (24-32%), aluminum (5.9-7.4%), calcium(6.2-12%), and iron, although numerous other substances were also present. Concentrations of various constituent parts vary by location, as it is thought that heavier materials settle out of the clouds closer to the origin. An American study analyzing the composition of dust events over Colorado also points to the presence of carbon monoxide, possibly incorporated in the clouds as they passed over industrialized regions of Asia.

[edit] Historical reports

The first known record of an Asian Dust event in Korea was in 174 CE during the Silla Dynasty. The dust was known as "Woo-To (雨土)" and was believed at the time to be the result of an angry god sending down dust instead of rain or snow.

Specific records referring to Asian Dust events in Korea also exist from the Baekje, Goguryeo, and Joseon periods.