Sonoma Technology scientists examined PM2.5 concentrations measured at 48 near-road monitoring sites across the U.S. in 2017, identified roadway contributions to PM2.5, and forecasted how fleet-turnover could affect near-road concentrations over time. Results will help inform agencies as they identify transportation projects of local air quality concern (POAQC).
This work was completed as part of Sonoma Technology's work on the Transportation Pooled Fund.
The results of this study were published in Transportation Research Part D: Transport and Environment.
The abstract of the article is below:
Transportation projects must undergo a transportation conformity hot-spot analysis if they are designated as projects of local air quality concern (POAQC). We examined concentrations of particulate matter 2.5 µm in aerodynamic diameter or smaller (PM2.5) measured in 2017 from 48 near-road monitoring sites across the U.S. Annual average PM2.5 increments, the difference between near-road and background PM2.5, were between 0.1 ± 0.2 µg/m3 and 2.0 ± 0.2 µg/m3 for sites without noted confounding factor(s). The highest PM2.5 increment from monitors ten or more meters from the roadway was 1.4 ± 0.2 µg/m3. Using modeled national average exhaust emissions, and associated near-road contribution to PM2.5, the upper bound of 2.0 ± 0.2 µg/m3 is projected to decrease 30% from 2017 to 2040, for the types of highways assessed here, assuming a roadway with 8% heavy-duty diesel vehicles and constant traffic volumes. These results can help inform transportation conformity POAQC designations.