Combustion-Related Organic Species in Temporally Resolved Urban Airborne Particulate Matter

Accurate characterization of the chemical composition of particulate matter (PM) is essential for improved understanding of source attribution and resultant health impacts. To explore this we conducted ambient monitoring of a suite of 15 combustion-related organic species in temporally resolved PM _2.5 samples during an ongoing animal exposure study in a near source environment in Detroit, MI. All of the 15 species detected were above the method detection limit in 8 hour samples. This study focused on two molecular classes: Polycyclic Aromatic Hydrocarbons (PAHs) and Hopanes measured in samples. Of the 12 PAHs studied, benzo[b]fluoranthene (169 pg m^-3), benzo[g,h,i]perylene (124 pg m^-3), and benzo[e]pyrene (118, pg m^-3) exhibited the three highest mean concentrations while 17α(H),21β(H)-Hopane (189 pg m^-3) and 17α(H),21β(H)-30-Norhopane (145 pg m^-3) had the highest mean concentrations of the 3 Hopanes analyzed in samples. Ratios of individual compound concentrations to total compound concentrations (∑ 15 compounds) showed the greatest daily variation for 17α(H),21β(H)-Hopane (11-28%) and 17α(H),21β(H)-30-Norhopane (8-20%). Diagnostic PAH concentration ratios ([IP]/[IP + BP] (range 0.30 - 0.45), [BaP]/[BaP+BeP] (range 0.26 - 0.44), [BaP]/[BP] (range 0.41 - 0.82), [Bb]/[Bk] (range 2.07 - 2.66), in samples reflected impacts froma mixture of combustion sources consistent with greater prevalence of petroleum combustion source emissions (gasoline, diesel, kerosene, and crude oil) compared to coal or wood combustion emissions impacts at this urban site. Results from this study demonstrate that short duration sampling for organic speciation provides temporally relevant exposure information.