Use of particle bound polycyclic aromatic hydrocarbon (PAHs) diagnostic ratios to assess pollution sources: Universal or local application?

Particulate Matter (PM) influences both global climate and public health. For this reason, regulators have set stringent standards for ambient PM concentration. Most anthropogenic PM is emitted from combustion sources. Among other compounds, these combustion processes produce a range of particle bound PAH; the relative concentrations of these compounds may be characteristic of the source, fuel, and combustion conditions. This is particularly the case for diesel engines, one of the major sources of PM in urban locations. In light of this, 40 samples were collected in Sydney and an additional 20 samples were received from Hanoi, Vietnam. After soxhlet-extraction in an organic solvent, the extracts were concentrated and analysed by GC/MS using internal deuterated standards to quantify PAH. PAH diagnostic ratios could be a useful tool when assessing the proportion of ambient particles which may be due to diesel emissions. However, these ratios were dependant on the local fuel and fleet conditions. Background information on local fleet emissions was essential to ensure the selection of the proper ratio and to be able to adjust its range. The observed ratios of selected PAH were consistent with a major contribution from diesel vehicles to total PAH with a peak in winter and lower emissions in autumn. In Vietnam, results suggested that particle levels were mostly due to diesel emissions at kerbside and in the rural site but their influence was lower in the residential area where other major sources may be making a contribution. This is an abstract of a paper presented at the 14th International Union of Air pollution Prevention and Environmental Protection Associations World Congress 2007 (Brisbane, Queensland 9/9-13/2007).