Low-income communities and communities of color that bear the brunt of polluted air, water, and soil in the United States know that the harm they face comes from more than a single source. These communities, known as environmental justice (EJ) communities, experience a host of overlapping stressors—that is, physical, chemical, and biological agents as well as nonchemical factors, such as socioeconomic conditions—that have an adverse effect on health. For example, they may be breathing high levels of air pollution from local industry while at the same time less likely to visit a doctor to treat their aggravated asthma because of language barriers or lack of health insurance. Stated another way, the same amount of pollution can result in more harm to people who are experiencing additional stressors. Cumulative impacts is a way to describe the combination of multiple environmental and sociodemographic stressors experienced by EJ communities, which contribute to persistent health inequities and disparities in environmental health threats.

In 2017, NRDC and its environmental justice (EJ) partner groups in Chicago (the Southeast Environmental Task Force, the Southeast Side Coalition to Ban Petcoke, and the Little Village Environmental Justice Organization) and Newark, New Jersey (the Ironbound Community Corporation) began to explore how describing environmental burdens in a cumulative framework could advance advocacy to protect public health in their respective cities. This issue brief describes some of the history, motivation, and evidence behind the cumulative impacts framework and provides a case study of how a cumulative impacts mapping analysis might be leveraged to promote policies that protect low-income communities and communities of color that are disproportionately burdened by environmental and social stressors.

As we move forward, science and policymakers must catch up with what EJ communities already know and account for cumulative impacts when creating environmental policy.