The U.S. Environmental Protection Agency on Sept. 14 denied petitions from Delaware and Maryland asking the agency to address smog pollution blowing across their borders from coal-fired power plants in other states. The states sought action under the Clean Air Act’s “good neighbor provision” that requires the agency to control upwind states’ air pollution that impair the ability of downwind states to meet their ozone standards. The agency said it does not have enough evidence that the upwind states violate the provision, and that cost-effective control strategy is already being implemented in the identified sources under the Cross-State Air Pollution Rule. Delaware complained against emissions from sources in Pennsylvania or West Virginia. Maryland alleged that three dozen units in Indiana, Kentucky, Ohio, Pennsylvania and West Virginia were not operating their pollution control equipment efficiently during the ozone season.