Although a lot of the pollution that plagues the Southeast comes from local sources, we also get imports from other locations.
This week smoke from forest fires as far away as Alaska are blowing into the Lower 48 states. The recent record-setting warm conditions have increased the length of the fire season there by up to 35 days since 1950, according to Climate Central. There are as many as 600 fires burning in Alaska and Canada now, and the smoke is drifting south. You can read an article about the fires at Gizmodo here.
Meanwhile, dust from the Sahara is drifting westward. A Greek forecast for the dust near the ground arriving in the Southeast was tweeted by Dr. Marshall Shepherd of UGA. An article from KVUE in Austin TX describes some of the climatic consequences of the dust here.
Of course, the dust from these sources is nothing compared to the massive dust storms in the 1930s Dust Bowl era. One of my friends posted a letter written on June 30, 1935 from a farmer in Eva, OK on the conditions there. You can read it at http://www.loa.org/images/pdf/Henderson_Dust_Bowl.pdf from the Library of America “Story of the Week”.