in overburdened communities. (8) The burden of proof that a proposed action will not harm communities should fall on polluting industries and on the Federal Government in its regulatory role, not the communities themselves. (9) Pollutants currently regulated by the Federal Government, including for example criteria air pollutants, may have additive and synergistic negative effects on human health and the environment when combined. (10) Cumulative impacts are the public health and environmental risks and impacts caused by the combined past, present, and reasonably foreseeable future releases of environmental pollution in a specific geographic area. Cumulative impact assessment considers sensitive populations and other social factors that may heighten vulnerability to environmental pollution and associated health risks. (11) Cumulative impact assessments built into permitting decisions are one critical tool for preventing increased environmental and public health degradation in overburdened communities. At its most basic, cumulative impact assessment requires studying the impacts of having multiple pollution sources and stressors combined together on public health and the environment. While the effects of a single pollutant from a single source may be less significant when analyzed in isolation, the cumulative impacts of multiple pollutants from multiple sources in combination with each other and with other social vulnerabilities degrade public health and the environment substantially. Cumulative impact assessments should be incorporated into pollution permitting decisions such that Federal regulators are required to deny permits that threaten public health and the environment. (12) The general failure of the Federal Government to consider and regulate potential cumulative impacts in pollution permitting decisions has resulted in the inequitable distribution of pollution across regions and overburdening of certain communities. (13) Federal Government inaction has forced some State and local governments to act on