Atmospheric polycyclic aromatic hydrocarbons: Source attribution, emission factors and regulation

Abstract

Original article can be found at: http://www.sciencedirect.com/science/journal/13522310 Copyright Elsevier Ltd. DOI : 10.1016/j.atmosenv.2007.12.010There is an increasing concern about the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the environment as they are ubiquitous in ambient air and some of them are among the strongest known carcinogens. PAHs and their derivatives are produced by the incomplete combustion of organic material arising, partly, from natural combustion such as forest and volcanic eruption, but with the majority due to anthropogenic emissions. The PAH concentration varies significantly in various rural and urban environments and is mainly influenced by vehicular and domestic emissions. The review serves as a database to identify and characterize the emission sources of PAHs and hence various approaches including diagnostic ratio (DR) and principal component analysis (PCA) are discussed in detail. These approaches allow individual PAHs to be associated with their origin sources. The factors that effect PAH emission and estimated emission rate are also discussed in this paper. Although the levels of low molecular weight PAHs are high in vapor phase, most of the probable human carcinogenic PAHs are found to be associated with particulate matter, especially in fine mode particles in ambient air. Many countries have proposed a non-mandatory concentration limit for PAHs, whereas the health risk studies conducted in relation to PAH exposure, urge that these pollutants should be given a high priority when considering air quality management and reduction of impacts. r 2007 Elsevier Ltd. All rights reserved

GC-MS analyses and chemometric processing to discriminate the local and long-distance sources of PAHs associated to atmospheric PM2.5

“…BaP MEQ (BaP mutagenic equivalent concentration) are calculated using mutagenic equivalency factors from Durant et al (1996) reflects the pronounced seasonal variations of PAH levels inversely following the ambient temperature, with higher concentrations during the cold periods. In general, summertime levels of PAHs tend to a minimum because of the increased photooxidation of the most reactive congeners, whereas wintertime levels are higher due to enhanced sorption on particles, the less intensive oxidation mechanisms, and the increase of domestic heating (Ravindra et al 2008a). Moreover, the lower height of the mixing layer and frequent thermal inversions during the cold periods may trap pollutants closer to the ground.…”

“…Ratios between concentrations of individual congeners have been frequently used as diagnostic of specific sources in combination with the use of factor analysis (Ravindra et al 2008a and references therein). Nevertheless, some limitations and weakness of PAHs source identification using these tools have been pointed out recently (Galarneau 2008;Dvorská et al 2011;Katsoyiannis et al 2011).…”

“…The first factor (41 % of the total variance) mainly links (loadings >0.6) Chry, BbF, BkF, BeP, and BaP, and secondarily (loadings, 0.4-0.6) BaA and IP. As some of these congeners were suggested as tracers for stationary emission sources (Ravindra et al 2008a), natural gas home appliances (Rogge et al 1993;Lee and Kim 2007), coal combustion processes (Wan et al 2006;Ravindra et al 2008a, b), and combustions of oil (Mantis et al 2005), this factor reflects a mix of stationary sources. The second factor (28 %) is made up of lighter congeners Fluor, Pyr, BaA, and secondarily links Chry and BghiP.…”

“…The second factor (28 %) is made up of lighter congeners Fluor, Pyr, BaA, and secondarily links Chry and BghiP. High factor loadings of lighter congeners along with BghiP were associated to traffic from both gasoline and diesel engines (Boström et al 2002;Ravindra et al 2008a;Callén et al 2008). The third factor (17 %) is mainly composed by the heaviest congeners (DBahA and BghiP) and secondarily by IP; its interpretation is not straightforward.…”

“…In urban and near-city environments, motor vehicles and domestic heating are the main emission sources, although other common anthropogenic sources are oil refining, waste incineration, various industrial activities, asphalt production, road dust, shipping, flying, agricultural burning of biomass, and wildfires (Ravindra et al 2008a).…”