What impact will the I-5 Rose Quarter Improvement Project have on air quality and greenhouse gas emissions?

The Environmental Assessment, released on February 15, 2019 and using the U.S. Environmental Protection Agency’s air emissions modeling tool, found that air quality and greenhouse gas emissions will slightly improve with the project compared to not building it. Once the project is built, the reduction in emissions and improved air quality will be due to the improved traffic flow, less idling on the highway, and reduced congestion.

An Environmental Peer Review panel of national technical experts, convened in May 2020, evaluated the air quality, greenhouse gas, and noise technical analyses that were conducted for the Environmental Assessment. The Peer Review Report supported ODOT’s findings for air quality, greenhouse gas, and noise impacts for the project. It also provided recommendations to incorporate into the project’s future design and construction phases, such as the requirement of low-emission construction equipment including electric vehicles.

We have also heard concern about air quality specifically at Harriet Tubman Middle School. The Environmental Assessment included a specific assessment of highway emissions near the school. The analysis showed that over time, with or without the project, there will be a large decrease in highway emissions because of improved fuel efficiencies in motor vehicles. The difference in emissions between constructing the project and not is minimal, however constructing the project would decrease emissions slightly more. The addition of a new sound wall between I-5 and the school would provide a dispersion barrier for air pollutants coming from traffic on I-5, thereby further improving air quality at the school.