2. Identification of regions
Monitoring for AAQ NEPM purposes is required for every region with a population of 25,000 or more. The AAQ NEPM gives a very broad definition of region, allowing each jurisdiction to determine its regions and their boundaries. The Peer Review Committee (PRC) accepted the following definition of region:
A region for the purposes of performance monitoring is a geographical area where the air quality (for a particular pollutant) is determined either entirely or in large part by the influence of a common collection of anthropogenic emissions sources.
NSW has defined regions for AAQ NEPM reporting based on the requirements of the Measure interpreted using the above definition and by referring to population data from the 1996 census. This includes considering the possibility that smaller urban centres may be sufficiently close together to generate a region with a total population greater than 25,000.
According to Clause 14(1) of the Measure:
the number of performance monitoring stations for a region with a population of 25,000 or more must be the next whole number above the number calculated in accordance with the formula:
1.5P + 0.5 = N
where P is the population of the region (in millions)
N = number of performance monitoring stations
Additional performance monitoring stations may be needed where the pollutant levels are influenced by local characteristics such as topography, weather or emission sources. Fewer performance monitoring stations may be needed where it can be demonstrated that pollutant levels are reasonably expected to be consistently lower than the stadards.
In the PRC AAQ NEPM Guideline Paper - PRC (2000b) - three types of regions were identified as follows:
Type 1 A large urban or town complex with a population in excess of 25,000 requiring direct monitoring and contained within a single airshed.
Type 2 A region with no one population centre above 25,000 but with a total population above 25,000 and with significant point source or area based emissions so as to require a level of direct monitoring.
Type 3 A region with a population in excess of 25,000 but with no significant point or area based emissions, so that ancillary data can be used to infer that direct monitoring is not required.
Moreover, PRC (2000b) considered the ABS 'urban centre' population data to provide a transparent basis for a preliminary assessment of regions for AAQ NEPM monitoring. The PRC Paper also notes that it is important that other issues:
such as local knowledge of region/airshed population, emission sources, topography and dispersion should also be considered. In applying the formula that guides the number of monitoring sites needed on the basis of population, the actual population in the affected airshed should be estimated by integrating up the ABS data as appropriate. The changes in population that can result from this integration may be substantial. In some instances it may raise the population above the lower threshold where monitoring needs to be considered. Moreover, a narrow application of the ABS population data should not be used as a justification for a lower level of monitoring than would result from a consideration of an airshed concept.
2.2 Urban centres in NSW
The 1996 Census, ABS (1996), counted some 6.04 million people in NSW. Following the guidelines in PRC (2000b) and using these data, there are fifteen urban centres with populations above the AAQ NEPM threshold of 25,000. In addition there are six centres with a population between 20,000 and 25,000. These centres are listed in Table 1
and shown in the map of NSW.
These data reflect the way that census data are collected. In particular, although the census lists it separately, Richmond-Windsor is usually considered part of Sydney and is not separately noted on Figure 1. Further, the Central Coast urban centre lies between Sydney and Newcastle. In this plan, there is no Central Coast region. Rather, the area in the Central Coast urban centre is divided between the regions associated with the urban centres of Sydney (to its south) and Newcastle (to its north).
2.3 Regions in New South Wales
Consideration of AAQ NEPM monitoring is required for each region with a population of 25,000 or more. Not all of the urban centres meeting this criterion reside in distinct airsheds. The most populated part of the state - running down the coast from the coastal plain of the Hunter River to the coastal ridge at Shellharbour - contains five of these urban centres, and one of the centres with a population between 20,000 and 25,000. Consideration of topography leads to the definition of three regions for this part of the state. These are called: Lower Hunter, Sydney, and Illawarra.
The area known as the Upper Hunter has significant emissions from coal-fired power stations. Within this area are the urban centres of Scone (3468), Aberdeen (1737), Muswellbrook (10,541), and Singleton (12,519). This is potentially a region containing more than 25,000 people and hence one requiring consideration of AAQ NEPM monitoring.
The topography of the area is not simple. In particular, a ridge about 10 km south of Muswellbrook separates Muswellbrook and Scone from the power stations around Lake Liddell. Singleton is some 25 km to the southeast of the lake. Indeed, the river itself flows around this ridge, running southwest from Muswellbrook to Denman where the Goulburn River joins it. It then resumes a coastal path to Singleton. Thus the area known as the Upper Hunter refers to the power stations and the nearest towns, Muswellbrook and Singleton rather than the natural river valley. The topography shows clearly that there is no region containing a population of 25,000 or more.
Further observational study is planned within the Hunter valley. NSW EPA will review the results of that work to reassess the current definition of two distinct regions in the area.
Monitoring is conducted within the area by industry. This monitoring is not suitable for AAQ NEPM purposes, but does provide information on the impacts of industry within the area. This monitoring shows that impacts from power station plumes are generally minor and local in effect.
Coffs Harbour is geographically close to Sawtell (population 13,240). Taken together these urban centres create a region with a population of 35,417. The remaining urban centres with populations between 20,000 and 25,000 are geographically distinct, with no other nearby urban centres. Further, consideration of urban centres with populations above 10,000 shows that there are none sufficiently close to others so as to constitute a region containing 25,000 people.
Thus in New South Wales there are fourteen regions in total - thirteen from the urban centres with population greater than 25,000, plus Coffs Harbour-Sawtell.
2.3.1 Sydney region
Sydney lies within its own region which has a contiguous population of around 3.8 million. The region and its population density are shown in Figure 2
. As can be seen from the map, the Sydney region extends from the southern boundary of the Wollondilly shire in the south to the northern boundary of the Hawkesbury and Wyong shires, and so includes the southern part of the Central Coast urban centre.
2.3.2 Lower Hunter region
Newcastle, its satellite towns, the northern parts of the Central Coast urban centre, and Maitland all lie in a single region to be termed the Lower Hunter. Maitland is some 20 kilometres to the north-west of Newcastle along the axis of the Hunter River. There are no topographic features that could lead to it being regarded as belonging to a different region. Note, however, that significant topography lies between the Hunter River and Cessnock, thus Cessnock is excluded from the region.
The coastal plain associated with the Hunter River extends south down the coast to include both Lake Macquarie and Tuggerah Lake. On this basis, the northern part of the Central Coast urban centre is included in the Lower Hunter region. This region has a population of around 460,000 people, the population density is given in Figure 3.
It should be noted that the EPA is currently undertaking work intended to clarify the extent to which the Lower Hunter and Sydney airsheds are interconnected. This will be used to refine this aspect of the monitoring plan in future.
2.3.3 Illawarra region
Wollongong and Port Kembla lie in a distinct region termed the Illawarra which has a population of around 220,000 people. Population density in the region is shown in Figure 4. The region is characterised by a coastal plain bounded by a steep escarpment to the west.
2.3.4 Remaining regions
All the remaining urban centres considered are located within separate airsheds and are therefore treated separately.
2.4 Region types
Within New South Wales, the Sydney, Lower Hunter and Illawarra regions are clearly of Type 1. They are already the subject of direct monitoring and will continue to be. As discussed above, the Central Coast population centre is included in the Sydney and Lower Hunter regions at present.
The situation in the rural population centres other than these will be discussed in greater detail in Section 3. However, in summary, Wagga Wagga, Albury-Wodonga, Tamworth, Orange, Dubbo, Bathurst and Canberra-Queanbeyan are all subject to the influences of smoke generated from wood burning for domestic heating and are thus also of Type 1.
Coffs Harbour-Sawtell and Port Macquarie, while significant population centres, are both located on the coast where mild winters prevail. Thus, apart from motor vehicle emissions, neither have significant domestic, commercial or industrial sources. Both are therefore Type 3.
The situation with Lismore is not clear. While it has a relatively dispersed population and mild winters, burning for agricultural purposes may be of significance. In the absence of specific information, Lismore is classified as Type 1. This will be reviewed in light of the results of campaign monitoring of PM10 within New South Wales.
For the Tweed Heads area, which is contiguous with the Gold Coast, it could be argued that it falls into Type 3, and it is not proposed to undertake direct monitoring here. The region is not densely populated and has no major industrial, domestic or commercial sources. Even so, it is part of a continuous airshed with the Gold Coast which will be monitored as part of the Queensland monitoring plan. The data acquired through the Queensland monitoring will be used to infer concentrations in the subregion of Tweed Heads and review this classification.
These classifications are summarised in Table 2.
2.5 Rural population centres with population between 20,000 and 25,000
Formally, regions with a population of less than 25,000 need not be assessed for AAQ NEPM monitoring. NSW believes that comment should be made regarding urban centres with a population between 20,000 and 25,000.
Four of the five NSW urban centres with populations between 20,000 and the 25,000 lie within their own region. These are Nowra/Bomaderry, Armidale, Goulburn and Broken Hill. Of these, only Broken Hill has significant industrial sources of emissions. In the absence of significant industrial sources, the only parameter remaining of potential concern is PM10. For Broken Hill the possible additional pollutant is lead. However, industrial monitoring shows concentrations are currently below the standard and falling as mining and associated industrial activity winds down.
Particulate monitoring (by high-volume sampler on a six-day cycle) in Nowra over a number of years has shown concentrations that never exceed the AAQ NEPM standard. Indeed, they rarely reach half the standard.
The EPA has, over a number of years, collaborated with the local council in Armidale to operate a nephelometer to measure fine particles. Armidale City Council with assistance from the EPA continues this work now. At present the population of the Armidale airshed is well below the 25,000 threshold. Should the population of Armidale grow, the need for AAQ NEPM monitoring will be re-assessed.
Similarly, Goulburn currently shows a slowly declining population. The need for AAQ NEPM monitoring will be reassessed should the population increase. Broken Hill shows a strongly declining population and it is not expected that AAQ NEPM monitoring is warranted either now or in the future.
NSW does not intend to undertake AAQ NEPM monitoring in any of these centres as part of this Plan.
Table 2: Regions classified by type
Page last updated: 26 February 2011