As the drought has dragged on, the soot has left the Sierra Nevada covered for weeks at a time. Dust clouds dot the rural roads here, and there is often a stripe of gray haze at sunset. Residents routinely avoid the outdoors in the summer or when they see (or, worse, feel) the film in the air. Sometimes, the air has been so thickly clouded with pollution that it is difficult to see across the California State University football stadium here