A ROK Drop favorite Robert Neff has an published in the Korea Times that explains how the yellow dust problem that has been plaguing Korea has actually been worse in centuries past than what has been seen recently:
For the past several days, the air quality in Korea has been horrible _ filled with dust and pollution. Many blame desertification in China due to its rapid industrialization but this phenomenon is not new _ it is one that has plagued the Korean Peninsula for hundreds of years.
Historical records from the Three Kingdoms period indicate dust storms occurred at least as far back as 174 A.D. One powerful dust storm in the early sixth century left the capital of Baekje shrouded in darkness as if it were night and a couple of decades later, Silla suffered one that lasted for five days. Perhaps the strangest of these weather phenomena took place in 644 when a red-tinged snow fell in Pyongyang.
The Annals of the Joseon Dynasty provide even more examples.
In November 1412, a horrendous dust storm mixed with fog blanketed the land. The visibility was so bad that people could not even see the person standing in front of them and the sudden spring-like weather melted the ice on the rivers. [Korea Times]
Mr. Neff provides more examples of the bizarre weather created by the yellow dust at the link. What I found of interest was that if this same bizarre weather happened today people would be claiming it is because of global warming.