Seoul tower is difficult to see — even close up — due to haze enveloping parts of Korea from sand and other particles blowing across the Korean peninsula from the Gobi Desert.

Seoul tower is difficult to see — even close up — due to haze enveloping parts of Korea from sand and other particles blowing across the Korean peninsula from the Gobi Desert. (Greg L. Davis / S&S)

SEOUL — It arrives with spring’s warm temperatures, an unwanted aerial guest that turns a blue sky brown.

Strong spring winds sweep tons of dust and dirt off stark plains in China’s and Mongolia’s Gobi Desert, carrying it over South Korea, Japan, the Pacific Ocean and, eventually, all the way to the United States.

In South Korea, the phenomenon is known as whangsa, or “yellow sand.”

It’s generally regarded as a nuisance, coating cars, streets and windows in a fine dust.

Pictures from Beijing in years past show fuzzy brown images, thick like snow.

But it’s also a health hazard, doctors say, irritating eyes and lungs.

The dust contains heavy metals such as lead, cadmium, copper and aluminum, which aggravate asthma and bronchitis and can cause other health problems, such as pinkeye.

The dust can severely affect people with respiratory illnesses and asthma, said Lt. Col. Lee Hee-choon, a physician and chief of clinical preventive medicine for Yongsan Garrison’s 18th Medical Command.

Last year, military health clinics saw increases of people with pinkeye, as the dust gets past the skin, the body’s first line of defense.

“People need to … limit their time outside,” Lee said.

The dust also carries mold and germs. South Korea’s Rural Development Administration is studying the effects of one germ type and six types of mold that may be harmful to plants, said Ko Hyun-kwan, a researcher.

Melting snow in the areas where the yellow sand originates should wet the ground, reducing the dust this year, said Chon Young-shin, a researcher with the Korea Meteorological Administration.

But generally, those areas are getting drier, she added.

Last year was one of the worst for yellow sand, Chon said. The People’s Daily, a Chinese newspaper, reported last year that on some days visibility in Beijing was reduced to less than 300 feet.

The dust clouds can cause difficulties for military flight operations.

They can start around ground level and extend 10,000 feet upward, said Air Force Lt. Col. John Shattuck, director of operations for the 607th Weather Squadron at Yongsan Garrison.

Satellites can track the clouds before they arrive in South Korea, Shattuck said. Typically, they take about two days to reach that country, he said.

During a bad storm, visibility can be reduced to a half-mile, Shattuck added, prompting a warning to operations units.

Lighter storms can reduce visibility to four or five miles.

So far this year, however, no bad storms have affected South Korea.

But “the season has just started,” Shattuck said. “The potential is still there.”

By May, the storms usually taper off. But for a few months, the meteorological conditions are just right to push the sand, Shattuck said.

Capt. Paul Yuson, weather flight commander for 51st Fighter Wing, said hourly observations are taken and an advisory may be issued if the dust or sand is severe.

“We treat yellow sand like we treat any other surface phenomenon like fog or smoke,” Yuson said.

This year, South Korea will set up five monitoring stations in China to record density of the yellow dust, Chon said.

The information will be available instantly to researchers, she said.

The yellow dust phenomenon dates back hundreds of years. During the Yi Dynasty in Korea in the 14th century, people saw the coming of the yellow dust as a sign that their king was bad.

The South Korean government has suggested tree-planting campaigns in China to help alleviate the problem.

The Korean National Institute of Health has issued these suggestions to minimize exposure to yellow sand:

• Wear a protective mask and glasses rather than contact lenses when outside.• Don’t go outside unnecessarily.• Keep windows closed.• Take a shower and brush your teeth after being outside.• Wash vegetables and fruit thoroughly.

— Choe Song-won contributed to this report.

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