Black carbon concentrations and diesel vehicle emission factors derived from coefficient of haze measurements in California: 1967–2003

Abstract

We have derived ambient black carbon (BC) concentrations and estimated emission factors for on-road diesel vehicles from archived Coefficient of Haze (COH) data that was routinely collected beginning in 1967 at 11 locations in the San Francisco Bay Area. COH values are a measure of the attenuation of light by particles collected on a white filter, and available data indicate they are proportional to BC concentrations measured using the conventional aethalometer. Monthly averaged BC concentrations are up to five times greater in winter than summer, and, consequently, so is the population's exposure to BC. The seasonal cycle in BC concentrations is similar for all Bay Area sites, most likely due to area-wide decreased pollutant dispersion during wintertime. A strong weekly cycle is also evident, with weekend concentrations significantly lower than weekday concentrations, consistent with decreased diesel traffic volume on weekends. The weekly cycle suggests that, in the Bay Area, diesel vehicle emissions are the dominant source of BC aerosol. Despite the continuous increase in diesel fuel consumption in California, annual Bay Area average BC concentrations decreased by a factor of ~3 from the late 1960s to the early 2000s. Based on estimated annual BC concentrations, on-road diesel fuel consumption, and recent measurements of on-road diesel vehicle BC emissions, diesel BC emission factors decreased by an order of magnitude over the study period. Reductions in the BC emission factor reflect improved engine technology, emission controls and changes in diesel fuel composition. A new BC monitoring network is needed to continue tracking ambient BC trends because the network of COH monitors has recently been retired. _________________________________________________________________________

High-resolution sampling and analysis of ambient particulate matter in the Pearl River Delta region of southern China: source apportionment and health risk implications

“…Diesel-powered vehicles produce very little CO initially (Rhys-Tyler et al, 2011). It is assumed that diesel vehicle tailpipe emissions are primarily responsible for motor-vehicle-related PM 2.5 concentrations in the Foshan urban airshed, consistent with international research (Kirchstetter et al, 2008;Kim et al, 2009;Wang et al, 2012;Targino et al, 2016). Therefore, CO is not associated with motor-vehicle-emitted particulate mat- Figure 6.…”

Characterization of macromolecular organic matter in atmospheric dust from Guangzhou, China

“…As yet, these isolation and characterization approaches have not been applied to dust, although hulis and BC in aerosol have been widely studied in the past (Havers et al, 1998;Krivácsy et al, 2000;Dinar et al, 2006;Taraniuk et al, 2007;Kirchstetter et al, 2008;Dutkiewicz et al, 2009;Sýkorová et al, 2009). In the present study, we isolated HAs, kerogen and black carbon (KB) and BC from dust collected in Guangzhou, China, and then characterized the chemical composition of the fractionated macromolecule organic matter using elementary analysis (EA), X-ray diffraction (XRD), organic petrographic examination (OPE), scanning electron microscopy (SEM), solid state 13 C cross-polarization and magic angle spinning nuclear magnetic resonance spectroscopy ( 13 C-CP/MAS NMR) and Fourier transformed infrared spectroscopy (FTIR).…”

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

“…Filter transmittance was judged at the time to be less useful for tracking atmospheric optics, in part because it did not fully capture in situ light scattering by hygroscopic particles (Burt 1961). More recently, archived CoH data have been reenvisioned as useful proxies for light absorption (Kirchstetter et al 2008).…”