LA's notorious air pollution is dropping in part because the vehicle fleet is getting a lot cleaner. That's especially true on the affluent Westside, where people buy new cars more often. But a neighborhood in Mar Vista, near the Santa Monica Airport, is a startling exception. North Westdale has ultra-fine particles that cause asthma, heart attacks, strokes and various birth problems in about the same concentration as Boyle Heights, which is surrounded by freeways. Suzanne Paulson headed a joint study by UCLA's Department of Atmospheric and Oceanic Sciences and the Institute for the Environment and Sustainability.