Cars and light trucks are no longer themajor source for smog and ozone pollution in most major U.S. cities, according to a report released by the American Automobile Association (AAA) yesterday. The study says cars and light trucks, which include sport utility vehicles (SUVs) and minivans, account for less than 24 percent of the emissions that lead to ground-level ozone problems in 25 major cities, excluding New York and Los Angeles.