This interesting story from the NASA Earth Observatory:
"In early July 2009, a dust storm that had raged over Iraq for over a week, and earned the reputation as the worst in living memory, traveled eastward to Iran. Once the dust arrived, Tehran officials closed government offices and schools for two days, cancelled numerous domestic flights, and warned the elderly, children, and individuals in poor health to stay indoors, according to news reports.
Iranian state television reported that this storm brought the worst dust levels to the country in three decades."
Another reason to be glad we live in Texoma!