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On-road black carbon instrument intercomparison and aerosol characteristics by driving environment
Citation:
Holder, A., G. Hagler, T. Yelverton, AND M. Hays. On-road black carbon instrument intercomparison and aerosol characteristics by driving environment. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 88:183-191, (2014).
Impact/Purpose:
The purpose of this study was to assess the spatial variation of black carbon and ultrafine particles in the on-road environment and identify dependency on road type or driving conditions.
Description:
Large spatial variations of black carbon (BC) concentrations in the on-road and near-road environments necessitate measurements with high spatial resolution to assess exposure accurately. A series of measurements was made comparing the performance of several different BC instruments (Single Particle Soot Photometer, Photo-Acoustic Soot Spectrometer, and Aethalometer) for high time resolution mobile measurements, capable of mapping spatial gradients. All instruments were highly correlated at high time resolution. However, the Single Particle Soot Photometer (SP2) BC concentrations were lower than the other measurements, which was attributed to BC size modes outside of the SP2 measurement range. BC and ultrafine particle (UFP) concentrations were two-fold higher on the highway compared to surrounding roads with lower traffic counts. Most BC particles were uncoated, with a geometric mean diameter of approximately 120 nm, which is smaller and less coated than aged urban BC. Concentrations were much lower during stop-and-go traffic than during free flowing traffic on the highway, providing evidence that transit time is not a good predictor of BC or UFP exposure.
