SEOUL, March 3 (Reuters) - South Korea closed schools on Monday and its factories producing memory chips stepped up safeguards, as a choking pall of sand mixed with toxic dust from China covered most of the country and other parts of Asia.
The annual "yellow dust" spring storms, which originate in China's Gobi Desert before sweeping south to envelop the Korean peninsula and parts of Japan, are blamed for scores of deaths and billions of dollars in damage every year in South Korea.
It issued a yellow dust warning at the weekend. On Monday, school districts in southeastern regions urged parents to keep kindergarten and elementary school children at home.
"We advised the closure because kindergarten, primary school students have weaker immune systems," said Min Eyu-gi, an education official in Busan.
An official with the Meteorological Administration said the first major storm of the season, which has also hit parts of Japan, was dissipating.
But forecasts from China said cold air and little rainfall would lead to more storms from Wednesday through March 11, Xinhua news agency reported.
Taiwan mostly avoids the toxic clouds but skies in Taipei on Monday were overcast, with the government telling people to wear surgical masks and avoid exercising outdoors.
In Japan, car drivers and train operators were asked to be on alert because the sandstorms had greatly reduced visibility.
The sand storms have been increasing in frequency and toxicity over the years because of China's rapid economic growth and have added to increased tensions with neighbours South Korea and Japan over recent years.
The dust picks up heavy metals and carcinogens such as dioxin as it passes over Chinese industrial regions, before hitting North and South Korea and Japan, meteorologists say.
Dry weather and seasonal winds in China hurl millions of tonnes of sand at the Korean peninsula and Japan from late February through April or May, turning the skies to a jaundiced hue.
The state-sponsored Korea Environment Institute said the dust kills up to 165 South Koreans a year, mostly the elderly or those with respiratory ailments, and makes as many as 1.8 million ill.
Annual economic damage to South Korea from the storms is estimated at up to 5.5 trillion won ($5.82 billion), according to the institute.
Hynix Semiconductor Inc, the world's second-biggest maker of memory chips, said it has had to step up its filtration systems and make employees take longer air showers to make sure the dust does not contaminate its production lines and damage chips, made using technology that operates on a microscopic level.
South Korean retailers, however, have spotted an opportunity, offering special scarves, hats and other accessories for the yellow dust season. ($1=944.5 won) (Additional reporting by Lee Jiyeon and Rhee So-eui in Seoul; Ralph Jennings in Taipei; Ian Ransom in Beijing and Teruaki Ueno in Tokyo, Editing by Jonathan Thatcher and Jerry Norton)
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