Yellow dust (More info from good old wiki!)
Asian Dust (also yellow dust, yellow sand, yellow wind, or China dust storms) 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 and Kazakhstan 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, as well as parts of the Russian Far East. Sometimes, the airborne particulates are carried much further, in significant concentrations which affect air quality as far east as the United States.
In the last decade or so, it has become a serious problem due to the increase of industrial pollutants contained in the dust and intensified desertification in China causing longer and more frequent occurrences, as well as in the last few decades when the Aral Sea of Kazakhstan started drying up due to a failed Soviet agricultural scheme.
Sulphur (an acid rain component), soot, ash, carbon monoxide, and other toxic pollutants including heavy metals (such as mercury, cadmium, chromium, arsenic, lead, zinc, copper) and other carcinogens, often accompany the dust storms, as well as viruses, bacteria, fungi, pesticides, antibiotics, asbestos, herbicides, plastic ingredients, combustion products as well as hormone mimicking phthalates. Though scientists have known that intercontinental dust plumes can ferry bacteria and viruses, "most people had assumed that the [sun's] ultraviolet light would sterilize these clouds," says microbiologist Dale W. Griffin, also with the USGS in St. Petersburg. "We now find that isn't true." 
Areas affected by the dust experience decreased visibility and the dust is known to cause a variety of health problems, not limited to sore throat and asthma in otherwise healthy people. Often, people are advised to avoid or minimize outdoor activities, depending on severity of storms. For those already with asthma or respiratory infections, it can be fatal. The dust has been shown to increase the daily mortality rate in one affected region by 1.7%.
Although sand itself is not necessarily harmful to soil, due to sulphur emissions and the resulting acid rain, the storms also destroy farmland by degrading the soil, and deposits of ash and soot and heavy metals as well as potentially dangerous biomatter blanket the ground with contaminants including croplands, aquifers, etc. The dust storms also affect wildlife particularly hard, destroying crops, habitat, and toxic metals interfering with reproduction. Coral are hit particularly hard. Toxic metals progagate up the food chain, from fish to higher mammals. Air visibility is reduced, including canceled flights, ground travel, outdoor activities, and can be correlated to significant loss of economic activity. Japan has reported washed clothes stained yellow.
Korea Times has reported it costing 3 million won, 6000 gallons of water, and 6 hours to simply clean one jumbo jet.