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Date of Award

Fall 2023

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Studies

Degree Name

Master of Arts (MA)


Environmental Studies

First Advisor

Abel, Troy D.

Second Advisor

Salazar, Debra J.

Third Advisor

White, Jonah


Toxic air pollution in the United States has been regulated through the Clean Air Act (CAA) since the 1970’s. Yet, a growing body of research suggests that the CAA’s air pollution management system has several blind spots. The CAA’s inability to identify and remedy pollution hot spots across the country. These hot spots are areas where air pollution exists but are often entirely overlooked because of the extreme hyperlocal scale and the current methods for identifying areas of concern outlined in the CAA for the Environmental Protection Agency. Researchers find that these hot spots are more prevalent in minority and low-income communities.

Because of the expense to install and operate traditional stationary air monitors, it is impossible to place a monitoring site in every community. My research explores a potential alternative to the traditional stationary air monitoring system set up in the CAA that may identify pockets of elevated toxic pollution. Using Orthotrichum lyellii as a bioindicator measuring six toxic pollutants, I created maps of potential toxic metal pollution hotspots in the Duwamish River Valley (DRV). This area includes the neighborhoods of Georgetown and South Park separated by the Duwamish River. This industrialized and heavily polluted area in South Seattle was revealed to ultimately contain hot spots of toxic air pollution. This project relied on data collected by community youths. I then applied spatial mapping to illuminate the Duwamish River Valley’s pollution disparities. Through this sort of mapping, it is possible not only to locate potential polluters in an area but to also empower communities to take action and improve the health and safety of the air they breathe.




CAA, Clean air act, moss, Duwamish River Valley, toxic air pollution, air pollution, biomonitor, community science, South Seattle


Western Washington University

OCLC Number


Subjects – Names (LCNAF)

United States. Clean Air Act

Subject – LCSH

Orthotrichales--Washington (State)--Duwamish River Valley; Air--Pollution--Washington (State)--Duwamish River Valley; Environmental monitoring--Washington (State)--Duwamish River Valley; Environmental justice--Washington (State)--Duwamish River Valley

Geographic Coverage

Duwamish River Valley (Wash.)




masters theses




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