A report by the Union of Concerned Scientists (UCS) suggests that most states are doing a fair to poor job of controlling emissions of hazardous diesel exhaust of school buses. According to the report, “Pollution Report Card: Grading America’s School Bus Fleets,” all states rely on high-polluting school buses, though a small minority of them are “ahead of the curve.” The report, which is based on a statistical analysis of each state’s bus fleets, said only six states and the District of Columbia earned good grades. The others received overall grades of “B-” or worse, based on estimated emissions of particulates, smog-forming pollution and greenhouse gases. The UCS recommended that governments step forward to help school districts replace older buses in their fleets with new, cleaner-burning vehicles. As part of that effort, the UCS recommended the formation of a federal Green School Bus grant program that would enable school districts to buy natural gas or advanced, low-emission diesel buses without tapping funds for the classroom. The report can be found on the Web at www.ucsusa.org.