The Agency often receives questions about cumulative impacts as it relates to air pollution and other factors. While there is not a universal definition of cumulative impacts, it often refers to the combined, incremental, and often long-term effects of multiple stressors caused by humans and nature, on people, communities, and ecosystems. For certain types of the Agency’s work - for example - the creation of our overburdened communities map, the Agency refers to the EPA’s general definition of cumulative impacts as “the totality of exposures to combinations of chemical and non-chemical stressors and their effects on health, well-being, and quality of life outcomes.” Because this definition is so broad, people often have very different ideas of what cumulative impacts means and includes in their communities.

The graphic below shows the Agency’s approach to cumulative impacts. Our Agency’s mandate, mission, expertise, and influence are in air quality, so our focus is on the light blue “Outdoor Air Pollution”, while the other topics in dark blue are covered by other agencies like local health jurisdictions and municipalities. Many of the factors listed in dark blue can increase the effects of air pollution, such as having a pre-existing health condition like chronic lung disease or limited access to healthcare due to socioeconomic factors. Other environmental stressors, such as water and soil pollution, can also impact health. These burdens add up and can make exposure to air pollution inequitable. Our approach uses data from the contributors in the diagram to develop our overburdened communities and focus topic priorities. Combined, these help us to prioritize discretionary air quality work so that we can do more to address air quality inequities in overburdened communities. This work often takes the form of applying for and administering grants that reduce air pollution in overburdened communities, conducting special air quality monitoring studies, engaging community in study results, and more.

This webpage describes general information about the Agency’s approach to cumulative impacts, for certain types of its work, and is intended to provide context on air pollution and overall health risks as well as how we identify overburdened communities. The Agency’s webpages do not use the term “cumulative impacts” in its regulatory context, including but not limited to as related to the National or State Environmental Policy Acts (NEPA or SEPA), which you can learn more about here:

• NEPA: https://ceq.doe.gov/publications/cumulative_effects.html
• SEPA: https://ecology.wa.gov/regulations-permits/sepa/environmental-review/sepa-guidance