Research indicates that ethnic minority groups experience disproportionate exposure to air pollution caused by vehicular transportation. It is well known that differential exposure to air pollution causes increased health risks in vulnerable communities. Disparities in air pollution exposure are significant since they exacerbate comorbidities, increasing the risk of diseases like COVID-19. This study examined the relationship between exposure to Transportation-Related Air Pollution (TRAP) and census tract racial demographics in Seattle, WA. We hypothesized that communities with greater percentages of non-white residents are more likely than white-dominated communities to experience greater exposures to TRAP, because of historical factors such as “redlining”, segregation, and discrimination. This is because they are forced to live in less desirable areas and are unable to resist polluting infrastructure in their neighborhoods. We used the Environmental Protection Agency’s Environmental Justice Database to relate diesel particulate matter (PM), a proxy for TRAP, to census tract demographics, from the 2020 U.S. census. We measured diesel PM concentrations at systematic distances along three North/South transects through Seattle, roughly corresponding with the location of Interstate 5 (I-5). Measurement locations were taken sufficiently far from I-5 so as to not be affected by I-5. We found no correlation between the percent non-white population and diesel PM concentration, thus rejecting our hypothesis. There are several reasons for our unsupported hypothesis: first, our transect did not adequately sample majority non-white neighborhoods. Second, diesel PM is only one proxy for air pollution, and may be distributed relatively evenly throughout our study area irrespective of racial demographics. An analysis of other pollutants may support our hypothesis. While it is optimistic that we failed to find disproportionate exposures to diesel PM in our study area, continued analysis of differential exposure to various forms of pollution is critical to identifying and addressing environmental injustice.

The quality and accessibility of greenspaces are positively correlated with urban quality of life. The presence of greenspaces increases mental and physical health, economic activity, air quality, and other critical facets of well-being. In this study, we tested the hypothesis that household income is an indicator of the quality and accessibility of greenspaces in Seattle. Specifically, individuals living in higher average household income areas experience higher quality and accessibility of greenspaces than individuals living in lower income areas. We utilized data from the American Community Survey on King County’s annual average household income, along with geographic information on public parks from the City of Seattle GIS database to relate park accessibility and quality to household income by census tracts. We defined accessibility as the number of parks present in a given tract. A Park Quality Index was used to assign a quality score to each park, allowing us to calculate an average park quality rating for each census tract. Park quality was determined by acreage and the presence of natural and man-made elements. We found a weak positive correlation between average household income and park quality but no correlation between income and the number of parks available in a census tract. While our findings showed only weak support for one part of our hypothesis, we believe the lack of support is in part due to the fact that census tracts are too large a scale for analysis. With growing evidence for micro-segregation by race (and by extension, income) within census tracts in Seattle, it is likely that lower income neighborhoods within larger census tracts do in fact experience reduced access to high quality greenspaces. Future research should investigate this question at the scale of neighborhood or city block in order to further investigate what is likely to be an environmental justice issue in Seattle.

Air pollution is not evenly distributed geographically or demographically. For historical reasons related to race and class, ethnically diverse neighborhoods often have a higher rate of negative health effects related to air pollution, as compared to predominantly white communities. In this study, we explore the relationship between the demographic indicator, "percent people of color," to exposure to air pollution and subsequent cancer risk in the Seattle/Tacoma area. Our analysis utilizes data from the Environmental Protection Agency’s Environmental Justice Screening and Mapping Tool, with the independent variable being the air toxics cancer risk, based on the National Air Toxics Association (NATA) calculated Cancer Risk from inhalation of air toxics and measured in percentiles of risk per million people. Our dependent variable, the percent people of color population, was collected from the 2015-2019 American Community Survey, a subset of the US Census, and is defined as everyone who does not identify as non-hispanic white. We performed our analysis using a disproportionate stratified random sample of census tracts from the King-Snohomish County dividing line in the north to the intersection of I5 and Highway 512 in the south, bounded by 122.05’ W on the east margin and the eastern shoreline of Puget Sound on the west margin. For each selected tract, we recorded percent people of color and NATA Air Toxics Cancer Risk National Percentiles. Our data reveals a positive linear relationship between cancer risk percentile and percentage people of color in the population. These findings highlight the importance of recognizing and addressing the lasting effects of racism on health, and the need for continued work towards securing environmental justice.