Here's mud in your eye (and ears and throat)You may want to think twice before you head out to enjoy the outdoors this spring. Meteorologists are predicting three to four more episodes of the Asian dust phenomenon in April and May, similar to the one that occurred March 21-23.
If you were in Korea during that veritable dust bowl, you could not have missed what has gone down as the worst of its kind. The thick yellow haze that enveloped the peninsula forced kindergartens and elementary schools to close for two days. The poor visibility shut down air traffic. Semiconductor manufacturers and precision instrument makers went on a state of high alert to fend off the microscopic granules that threatened their delicate wares.
According to the Korea Meteorological Administration, on March 21, the dust reached a peak concentration of 1,407.3 micrograms of sub-10-micron particles per cubic meter (a micron is 1/1000th of a millimeter). That is three times higher than the dust storms of last year, and nearly 10 times the environmental standard of 150 micrograms per cubic meter.
Asian dust, also known as yellow sand, yellow dust or Asian sandstorms, begins in the inland deserts of Gobi and Taklamakan in northern China. Convection currents of warm and cold air force dirt and other particles into high altitudes, usually around three to five kilometers in the atmosphere. There the dust blows eastward at some 30 meters per second, crossing the Yellow Sea and inundating Korea.
Although the phenomenon has occurred more often in recent years - from six days in 1999 to 10 days in 2000, and a whopping 27 days in 2001 - it is not something new. The oldest recorded Asian dust event in Korea goes back to the year A.D. 174 during the Silla Kingdom. Since then, historical documents have recorded days of what sound like the apocalypse: "yellow rain," "red snow," "dust rain," "dust fog" and "blood rain that soaked the leaves red," all thought to refer to Asian dust storms.
But the rapid industrialization and deforestation of China is exacerbating the phenomenon, increasing the area where the dust originates and the amount of dust. The Xinhua News Agency of China reported that the most recent yellow sandstorm dumped 30,000 tons of dust on Beijing.
The desertification of China has accelerated in the last couple of decades. According to the Ministry of the Environment, around the 1960s, about 1,560 square kilometers of land turned into desert each year. But more recently, that has grown to 2,460 square kilometers, an area about four times the size of Seoul. Because of recent droughts, nearly 90 percent of Mongolia is also on the verge of turning into desert.
While about 30 percent of the Asian dust settles in China and Mongolia close to the area it originates, another 20 percent is transported to surrounding regions within those countries. But that leaves a hefty 50 percent that travels longer distances, to Korea, Japan and the Pacific Ocean.
The time it takes for the dust to arrive in Korea depends on the speed of the high altitude air currents, from as little as one day to as long as eight. When the original sandstorm is large, the dust can travel so far across the Pacific Ocean that it can be seen as haze in North America.
The increased amount of dust in the air means more than just the inconvenience of having to wash your dusty car. The tiny particles pose health hazards, according to doctors and scientists.
In fact, the number of deaths reported on days of yellow sand is higher than the daily average. Deaths attributed to cardiovascular and respiratory problems rise dramatically, according to a study by a team of Korean doctors and a meteorologist. The research traced the rate of deaths among Seoul residents from March to May, 1995-1998, comparing the days of Asian dust events and nondust days.
During the period studied, the death rate on yellow sand days was 1.7 percent greater than on normal days, everything else being equal. Deaths related to cardiovascular illnesses, asthma and other respiratory illnesses shot up 4.1 percent, and the death rate in people over 65 years old went up 2.2 percent.
"The fact that a single factor caused such a change in the rate of deaths indicates that yellow dust is very harmful," said Kwon Ho-jang, a professor of preventive medicine at Dankuk University School of Medicine, one of the joint authors of the study.
Blame the airborne specks. Upon inhalation, the tiny particles can enter the lungs, causing pneumonia or thrombosis, aggravating cardiovascular conditions. During the study period, the amount of particulate matter up to 10 microns in diameter was an average of 101.1 micrograms per cubic meter, compared to an average of 73.3 micrograms per cubic meter on days without the yellow sand.
The best thing to do during an Asian dusting, of course, would be to stay at home and keep all doors and windows closed. "Dust that is less than 10 micrometers can be inhaled through the nose and the mouth and reach the lungs," says Paik Jae-joong, M.D., at the National Medical Center. During a dust storm as severe as the one last month, everyone, not just the young, the elderly and those at high risk, should refrain from going outside, he advises.
Wearing a mask over the mouth and nose when venturing outside will help the problem somewhat, as it can act as a barrier to some of the larger dust particles. Thoroughly washing hands and feet in running water and gargling upon returning home can minimize further contact with the dust as well.
Eye problems are also a common complaint during the duststorms. "Rubbing your eyes when they have been exposed to the dust will irritate them, potentially leading to conjunctivitis and keratitis," says Ju Cheon-gi, professor of ophthalmology at Kingman St. Mary's Hospital. He advises rinsing the eyes and the nose in lukewarm running water after coming home.
by Kim Hoo-ran