Air monitoring at a PM_2.5 hot spot caused by diesel truck emissions

The University of Tennessee and Oak Ridge National Laboratory conducted an air monitoring study at the Watt Road interchange on I-40 in Knoxville, TN, to illustrate the hourly, day-of-week, and seasonal patterns of PM_2.5 resulting from diesel truck emissions on the interstate and at the truck stops. Most of the PM_2.5 concentrations occurred during the night when the largest contribution of emissions was from idling trucks rather than trucks on the interstate. A nearby background air monitoring site was used to identify the contribution of regional PM_2.5 emissions, which also contributed significantly to the concentrations measured at the site. The average PM_2.5 concentration at the Ramp Site attributable to idling trucks was 5.9 μg/cu m, while the concentration attributable to exhaust emissions from vehicles on the interstate was only 1.7 μg/cu m. In both cases, the PM_2.5 concentrations were well below NAAQS and should not be a significant "hot-spot" problem. This is an abstract of a paper presented at the AWMA's 99th Annual Conference and Exhibition (New Orleans, LA 6/20-23/2006).