Assessment of mobile source air toxics in an Environmental Justice Denver community adjacent to a freeway.

Air pollutant concentrations are often higher near major roadways than in the surrounding environments owing to emissions from on-road mobile sources. In this study, we quantified the gradient in black carbon (BC) and air toxics concentrations from the I-70 freeway in the Elyria-Swansea environmental justice neighborhood in Denver, Colorado, during three measurement campaigns in 2017-2018. The average hourly upwind-downwind gradient of BC concentrations from the roadway was 500-800 ng/m, equal to an increment of approximately 30-80% above local background levels within 180 m of the freeway.