The Congressional Research Service argued in report October 25 that the U.S. Court of Appeals for the District of Colombia’s decision to remand regulations designed to reduce power plant pollution that crosses state lines could make it more challenging for some areas to comply with air quality standards for fine particulate matter. The report, 2006 National Ambient Air Quality Standards for Fine Particulate Matter (PM2.5): Designating Nonattainment Areas, finds that certain areas could face difficulty due to the Environmental Protection Agency’s delay of air toxics standards for boilers, its proposed two-year compliance delay for cement kiln air toxics standards, and its decision to delay mercury air toxics standards for new coal-fired power plants.