4.3 Project design for PAHs
In winter some parts of Sydney and a number of larger towns in the Great Dividing Range suffer from visibly high levels of smoke associated with solid fuel heating and still weather conditions. The study set out to determine the types and indicative concentrations of PAHs in ambient air in these problem areas with a focus on the predicted winter seasonal peak.
Twenty-two representative sites in the urban areas of Sydney, Newcastle and Wollongong, and selected country regional centres were sampled for PAHs. There were six sites in Sydney, three in or near Newcastle, seven in and around Wollongong plus Nowra to the south, and five sites in the Great Dividing Range (Armidale, Cooma, Lithgow, Tumut, as well as Orange for a shorter sampling period). The last five sites in the Great Dividing Range are all high in altitude, making them very cool in winter with widespread use of solid fuel heaters.
At all sites except Orange, measurements were made once every six days using a high-volume sampler which draws air through a filter paper at a fixed flow rate for 24 hours per sample. (In Orange, sampling occurred over a different period and for 16 hours. The results for this site are therefore reported separately from the others.) The filter papers were then weighed, their contents extracted with solvent and the individual PAHs separated and measured by gas chromatography-mass spectrometry to derive the types of PAHs present and their mass.
The study analysed 11 PAHs present in particulate form, which is how they are usually found after solid fuel combustion. As gaseous PAHs could not be measured using the available technique, the results may underestimate contributions from some mobile sources, such as diesel engines.
A total of 268 samples was collected across the sites between August 1997 and February 2001. The majority of the samples were in winter (201), with the balance spread between summer (47), autumn (6) and spring (14).
Values presented as `Total PAHs' in this report are the totals of the following 11 PAHs found as particles:
Page last updated: 26 February 2011