For dust, Madison's air ranks as the 24th most polluted, out of 277 cities.
Last Saturday during a thaw, I could see dust fallout on the surface of Lake Mendota. The Lake has been ice-covered for only a few weeks, so you can see how rapidly dust accumulates.
The dust floated on meltwater, and blew into a row along the edge of this icy pool.
One of the largest contributors to dirty air is construction in Madison--our largest industry.