A team of 32 experts, convened by the Nature Conservancy and the Cary Institute of Ecosystems Studies, recently evaluated air pollution’s effects in the Northeast and Mid-Atlantic regions of the United States and identified the conservation implications. This report summarizes their findings about the significant air pollution impacts to several major ecosystem types, evaluates the use of air pollution loading limits to conserve biological resources and presents a Call to Action for advancing critical loads and expanding national air pollution monitoring.