Denver residents who live along Interstate 70 have been convinced for years they breathe more pollution than people living in other parts of the city.
Now first-of-its-kind research from a University of Colorado Boulder doctoral student proves some neighborhoods are more polluted than others, and it illustrates how redlining and other racist housing practices pushed people of color into those neighborhoods.
Alexander Bradley, a doctoral student studying atmospheric chemistry, used satellite imagery showing air pollution by census tract and old maps of redlined Denver neighborhoods to connect polluted air to the disproportionately impacted neighborhoods of Globeville, Elyria-Swansea and Commerce City.
“Pollution is not equally distributed for people of different racial and ethnic groups in Denver,” Bradley said. “Where people live is dictated historically by racist practices such as redlining and race-restricted neighborhood covenants.”
Bradley’s research was published Wednesday in the journal Environmental Science & Technology. The ability to use satellite imagery to pinpoint air pollution by neighborhoods and compare pollution levels within the same city is relatively new.
The study looked at levels of nitrogen dioxides and particulate matter because those were the pollutants measured by the satellites Bradley used in his research. Maps showed intense levels of those pollutants hanging over Commerce City and north Denver and then dissipating as the researchers shifted their focus further away from those areas.
They used maps from the 1930s and 1940s that showed which neighborhoods were redlined, a practice of excluding certain communities from being eligible for bank loans because of the races and ethnicities of the people who lived there.
“That’s important because I think that every city has a story of why people live where they do, and that affects who is affected most by pollution,” Bradley said.
Joost du Gouw, a CU Boulder professor who is Bradley’s doctoral adviser and one of the report’s authors, said the scientists were not sure whether air pollution was different across Denver. That’s because the city’s air quality is impacted by wildfires, oil and gas drilling and agriculture — all things that are outside the city’s boundaries and could blow anywhere.
But the data confirmed that Commerce City and north Denver bear the brunt of the pollution, he said.
“The districts that were redlined almost 100 years ago still have the highest levels of pollution,” du Gouw said.
A high percentage of the polluted air comes from the cars and trucks whizzing down I-70, Bradley said. The neighborhoods also are close to interstates 25 and 76.
Nearby industrial sources such as the Suncor Energy oil refinery also have a big impact on air pollution, du Gouw said.
But there are solutions, both scientists said.
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A push to increase the use of electric vehicles and improve public transportation would reduce harmful emissions along the interstates. And laws that force industrial polluters to clean up would improve the air for people who live in north Denver and Commerce City, they said.
The findings were published just as a slate of air quality bills are expected to be filed this week at the Colorado legislature. Those bills will attempt to reduce emissions, increase enforcement of major polluters and change how air-pollution permits are issued.
While the scientists did not release their findings in anticipation of looming political battles over air quality, the research could be helpful for those who are pushing for improvement, du Gouw said.
“Change is not driven by scientists, but it comes when people ask for change and when the evidence is strong,” he said. “What we can bring to the table is strong evidence for these disparities and why they are occurring. This evidence can hopefully be useful to justify change.”
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