Yellow sand: an annual rite of spring Published April 12, 2007 By Senior Airman Brok McCarthy 51st Fighter Wing Public Affairs OSAN AIR BASE, Republic of Korea -- Every year between March and May, servicemembers stationed in the Republic of Korea may notice a yellowish haze in the air. Yellow sand, as it is called, is blown in from the deserts of China and Mongolia. "Yellow sand is made up of very fine particles of sand as well as other things collected from the air while it's being blown toward Korea," said Maj. Deborah Carr, 51st Medical Group public health flight commander. "It can decrease visibility, but it can also cause eye and respiratory problems in some people. The elderly and very young tend to be particularly sensitive." Yellow dust is measured in dust concentration micrograms, (ug)/m3, on a scale that goes from zero to 1,000 plus. U.S. Forces Korea has created recommendations for outdoor activity based on the current level of dust in the air. To see what the recommendations are, click here. Yellow sand sweeps into Korea every year because of the transitional season that increases winds over the China/Mongolia Gobi Desert region, said Capt. Michael Buchanan, 51st Operations Support Squadron weather flight commander. "The transition season creates conditions over the Gobi Desert that are similar to Shamal, high winds in Saudi Arabia responsible for creating sand storms," he said. "During this time of year, the ROK is dominated by northwesterly winds originating in Mongolia. The yellow dust is carried by these winds until it settles over the ROK." "We expect yellow sand levels to be higher than normal this year due to a drought in China and Mongolia," Major Carr said. "It's a good idea for people to pay close attention to the current conditions and follow the activity recommendations." Regardless of the yellow sand levels, Major Carr recommended people stay indoors if they are being bothered by the sand or stay outside only as long as necessary if they need to go outside. She also said that cloth masks don't do much to keep from inhaling the yellow sand due to the small size of the particles. People can expect to see yellow sand subside mid-May due to Changma setting up, causing winds to come from a southerly direction rather than a northerly, Captain Buchanan said. Changma is the weather system that is mostly responsible for Korea's monsoon season in June and July. To find out the current yellow sand health alert level, people on Osan can tune into Channel 12. Everyone else can find the current conditions on the USFK Web site by clicking here.