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You are here: Home > Environmental issues > Air > Air toxics > Dioxins, organics, polycyclic aromatic hydrocarbons & heavy metals > 4.4 Results

4.4 Results

Table 7 (an average of the Sydney, Newcastle and Wollongong sites plus all other sites, except Orange) and Table 8 (Sydney sites) summarise and compare the winter and summer data for each sampling region or point.

Figures 5 and 6 also present these results graphically. The concentrations are reported in nanograms per cubic metre (ng/m³). A nanogram is 1 x 10^-9 grams or 0.000000001 grams.

Table 7: Total PAHs (24-hour averages: ng/m³) winter and summer-Sydney, Newcastle and Wollongong sites (average of each group) and all other sites (except Orange)

	Nowra	Sydney (average of all sites)	Wollongong (average of all sites)	Newcastle (average of all sites)	Tumut	Cooma	Armidale	Lithgow
WINTER
Average	0.92	4.47	1.71	2.68	7.16	7.68	8.62	23.8
Max.	1.67	17.5	9.62	13.0	14.7	17.7	24.0	52.3
Samples	6	52 (6 sites)	59 (7 sites)	31 (3 sites)	14	13	5	14
SUMMER
Average	-	0.62	0.62	0.56	0.82	0.33	0.28	0.69
Max.	-	1.39	1.79	2.82	2.55	0.59	0.32	1.42
Samples	Nil	14 (4 sites)	8 (2 sites)	11 (3 sites)	4	4	2	4

As the results for all seven Wollongong sites are similar, they are reported as a group average. This is also the case with the Newcastle results. There is greater variability in the results across the six Sydney sites.

The seven samples collected in Orange (all in winter and over a shorter sampling period than other sites) averaged 10.9 ng/m³ with a maximum of 30.7 ng/m³. These results were higher than the levels in Armidale, Cooma and Tumut but lower than those in Lithgow.

Table 8: Total PAHs (24-hour averages: ng/m³) winter and summer-Sydney sites

	Richmond	Lindfield	Rozelle	Blacktown	Sydney CBD	Earlwood
WINTER
Average	1.56	3.59	3.97	4.29	7.17	7.35
Max.	3.07	13.2	11.4	14.3	14.3	17.5
Samples	8	12	8	10	4	10
SUMMER
Average	0.22	-	0.80	0.67	-	0.97
Max.	0.29	-	1.39	0.92	-	1.30
Samples	4	Nil	4	4	Nil	2

Figure 5: Seasonal variations in PAHs (24-hour averages: ng/m³)-Sydney, Newcastle and Wollongong sites (average of each group) and all other sites (except Orange)

Figure 6: Seasonal variations in PAHs (24-hour averages: ng/m³)-Sydney sites

Given the study's focus on winter and the limited data from other seasons, only general comparisons are possible between seasons. Overall, the average winter PAH values were between 2 and 10 times higher than the summer samples at coastal urban sites, but between 8 and 35 times higher in the colder Great Dividing Range locations.

Average winter PAH concentrations in Lithgow were high: two to three times those in other Great Dividing Range towns. From observations in the field this is suspected to be a result of the greater use of coal for heating and cooking during the colder months and localised meteorological conditions.

Although there were only a few measurements in autumn (Armidale: 1; Tumut: 5) and spring (Lithgow: 8; Tumut: 6), they were much lower than winter levels of PAHs, consistent with the interpretation that the major source in the colder months is the burning of solid fuels, mostly for home heating.