In August and September, accumulated smoke and smog from seasonal agricultural burning and charcoal production in southern Africa gets "recycled"across many southern Africa countries, including Angola, Democratic Republic of Congo, Zimbabwe, and Zambia. At that time of year, a semi-permanent area of high atmospheric pressure takes up residence over that part of the continent, and the air re-circulates in a counterclockwise spin around the high. Air does escape from this spin-cycle at time...