Abstract for presentation at 14th IUAPPA World Congress

The contribution of secondary organic aerosol (SOA) to PM in Australian cities is very poorly quantified. SOA is produced by the oxidation of volatile organic compounds (VOCs) of biogenic or anthropogenic origin, to produce semi-volatile compounds that partition to existing particles. Recent work has suggested that oligomers may subsequently form by heterogeneous reactions after initial partitioning from the gas to particle phase. Hence the correct mixture of VOCs and oxidants such as sunlight, ozone and oxides of nitrogen will result in SOA formation. Since these combinations exist in Australian cites (and non-urban areas) the presence of SOA in PM in Australian cities can be predicted although current capabilities make it difficult to quantify.
The extent of the SOA contribution to PM in Australian cities may effect compliance to air quality standards, particularly the revised PM NEPM. In addition, recent epidemiological research suggests that human morbidity and mortality may be related to the fine fraction of PM (PM_2.5); however, the mechanism for this relationship is still not understood. SOA is certainly a potential candidate.
Currently no accurate cost-effective methods for the identification and quantification of SOA exist, either internationally or within Australia. Our knowledge of SOA formation stems mostly from smog chamber experiments. This presentation reports on the progress of the Department of Environment and Heritage funded Clean Air Research Program Project “Development of tools for the identification and quantification of SOA in Australian cities", particularly the potential for using aerosol volatility as such a tool.