Tom Beer, Michael Borgas, Willem Bouma, Paul Fraser, Paul Holper and Simon Torok
CSIRO Atmospheric Research
prepared for the 2006 Australian State of the Environment Committee, 2006
Air quality and air pollution are of community concern for a number of reasons, with reduced visibility being the most evident. While it is often difficult for people at ground level to realise that on a still, sunny day there can be a large amount of pollutants in the air, workers and residents in high-rise buildings, or air travellers coming in to land, will easily see the pollution haze.
Air pollution also causes soiling and corrosion; sandstone buildings discolour and fine details, such as gargoyles and stone fretwork, slowly disappear. In the vicinity of bushfires or intensive mining operations, washing that is hung out to dry may be badly soiled.
The greatest concern is the effect that air pollution has on environmental and human health. In 1998, the National Environment Protection Measure (NEPM) for Ambient Air Quality specified that the ‘desired environmental outcome of this measure is ambient air quality that allows for the adequate protection of human health and wellbeing’. In recent years, this major focus on human health effects has been specifically targeted at particulate matter (PM). The reason for this is that there has been considerable epidemiological evidence that established a link between particulate matter pollution and mortality (Dockery et al. 1993). Concern was initially directed at PM10, particulate matter with an aerodynamic diameter of 10 microns or smaller, but more recent work (Schwartz et al. 1996) has implicated the fine particulate matter with an aerodynamic diameter of 2.5 microns or smaller (PM2.5).
The health effects of air pollutants are determined by the cumulative dose that an individual inhales. The dose itself depends on a number of variables, one of which is the concentration of the pollutant in the ambient air.
Although greatest concern is directed at particulate matter, high levels of any of the ‘criteria pollutants’ cause air to be considered polluted. Listed in Table 2, air quality standards have been set under the NEPM for Ambient Air Quality (EPHC, 2004a). These standards—in the form of maximum permissible concentrations—were initially set in the NEPM for Ambient Air Quality in 1998. The goal of the NEPM is to achieve these standards (except for PM2.5) by 2008. The PM2.5 advisory reporting standards are to be reassessed during the next review of the NEPM.
There is also a NEPM for air toxics (hazardous and cancer-producing air pollutants) as well as a NEPM known as the National Pollutant Inventory (NPI) that provides an inventory of the total mass of pollutants emitted to the air (and water) by industrial and other sources.
|Pollutant||Averaging Period||Maximum concentration||Maximum allowable exceedences|
|Carbon monoxide||8 hours||9 ppm||1 day a year|
|Nitrogen dioxide||1 hour||0.12 ppm||1 day a year|
|1 year||0.03 ppm||None|
|Ozone||1 hour||0.10 ppm||1 day a year|
|4 hours||0.08 ppm||1 day a year|
|Sulphur dioxide||1 hour||0.20 ppm||1 day a year|
|1 day||0.08 ppm||1 day a year|
|1 year||0.02 ppm||None|
|Lead||1 year||0.50 μg/m³||None|
|Particles as PM10||1 day||50 μg/m³||5 days a year|
|Particles as PM2.5||1 day||25 μg/m³||None specified|
|1 year||8 μg/m³||None specified|
Source: From data in National Environment Protection Council (2005b, p.7)
The original Ambient Air Quality NEPM was varied in May 2003 with the inclusion of air quality advisory reporting standards for PM2.5.
The Ambient Air Quality NEPM also includes monitoring protocols that specify the methods used to measure the pollutants, and it offers instructions on locations for designated NEPM monitoring stations.
The indicators that accompany this commentary show the maximum concentrations of the criteria pollutants in Australian capital cities over time. In 2004, the Australian Government produced a State of the Air report based on data from each of the states and territories. This report (DEH 2004a, 27–164) provides detailed data and analyses of all of the criteria pollutants up to 2001, including information on the trends in the percentiles of the pollutants which enable one to examine the trend in selected extreme values.
Air pollution depends on an interplay of factors. The most important are the nature and quantity of the pollutants that are emitted, and the meteorological conditions. Pollutants are emitted every day at much the same rate in metropolitan airsheds, but air pollution is serious only on a few occasions. This also means that considerable variability in year-to-year results is probably indicative of climatic variability, as is evident in the ozone results for Sydney; however, the peak ozone levels experienced by most cities are close to or above the NEPM standard, with no evidence of a downward trend. It is particularly evident in Sydney (Figure 14).
Source: DEH State of the Air Report (2004a, Table A4.15).
The concern here is twofold. Firstly, there is no clear decline in pollution levels and, in fact, there is considerable year-to-year variability. Secondly, when the NEPM standards were first declared, there was considerable community pressure to set more stringent standards. In particular, there was pressure to set the one-hour average for ozone at 0.08 ppm, rather than 0.10 ppm (National Environment Protection Council, 2005a, p. 3). If this more stringent value were to be used as the criterion, then the ozone situation would be of greater concern in every Australian urban area. Similarly, if Australia adopts an eight-hour standard, which is increasingly being adopted overseas, then the ozone situation in major cities in Australia is also likely to be of greater concern.
Ambient lead concentrations are about one-tenth of the NEPM standard and do not represent a health or pollution concern in Australian capital cities. The gradual phase-out, and since 1 January 2005 the total elimination, of lead in petrol accounts for the decline.
Nitrogen dioxide concentrations indicate emissions from industry as well as motor vehicle emissions. Ambient concentrations of nitrogen dioxide are below the NEPM one-hour and annual standards. The highest annual nitrogen dioxide reading of 0.021 parts per million (ppm), observed in Sydney during 1997, is below the standard of 0.03 ppm.
Since 1998, carbon monoxide has not exceeded the NEPM standard in any Australian city. The decline since 1998 is most probably a result of improved catalyst performance of newer vehicles arising from the introduction of Australian Design Rule (ADR) 37/01 in 1997, and a slight lowering of the average age of the motor vehicle fleet. At 31 March 2002 it was 10.5 years, compared with 10.7 years at 31 October 1997 (Australian Bureau of Statistics, 2002, p. 13).
Sulphur dioxide levels in Australian capital cities are well below the NEPM one-hour, one-day, and one-year standards. The lowering of sulphur levels in diesel (to 500 ppm in 2002 and 50 ppm in 2006) and petrol (to 150 ppm in 2005 and 50 ppm in 2008) will help to ensure that this continues.
Virtually every capital city has at least one occasion in the year when the PM10standard is exceeded, in many cases because of bushfires . The NEPM allows five exceedences per year of the 50 μg/m³ value precisely because of this difficulty with bushfires, and so all capital cities are within the NEPM standard.
Places such as Prince of Wales Bay in Tasmania (the PM10 monitoring station for Hobart) show exceedences of the PM10 standard when a type of PM10 measuring instrument known as HiVol sampler is used, but no exceedences when a type of PM10 measuring instrument known as TEOM is used. The reason for this is that the TEOM heats the sample, so volatile material is lost from the collecting filter; the HiVol data are, therefore, more representative than the TEOM data of actual PM10 measurement.
It is of concern that all four cities that report PM2.5 have peak levels that are above the advisory reporting standard (Figure 15). Effective control will require identification of the source of these fine particles. One way to identify such sources is to examine the observed PM2.5/PM10 ratio.
Source: DEH State of the Air Report (2004a, Table A4.56)
Because PM2.5 is a subset of PM10, the PM2.5/PM10 ratio has a value of one when all particles in a particular set of measurements are below 2.5 microns in size. In general, particles from combustion and from photochemistry tend to be fine, so that the PM2.5/PM10 ratio is large, whereas particles from erosion (such as the wear of vehicle tyres) are larger in size, so that the PM2.5/PM10 ratio is smaller. The limits in the annual average PM2.5/PM10 ratio are illustrated by data from 1996, when Brighton in Victoria reported 0.41 whereas Lidcombe in New South Wales reported 0.68 (DEH 2004a, p. 285). All subsequent annual averages have been within this range, the PM2.5 fraction constituting 0.41–0.68 of the total PM10, indicating that combustion, photochemistry, erosion and probably other sources all play a role in the production of urban particles.
Air toxics are air pollutants that have the potential to seriously affect the health of humans. In some cases they are known or suspected to be carcinogenic. A NEPM for air toxics was agreed in December 2004 to deal with benzene, formaldehyde, benzo(a)pyrene (as a marker for polycyclic aromatic hydrocarbons, PAH), toluene, and xylenes. Measurements of air toxics have been sporadic, but it is expected to improve, because the NEPM includes a national environment protection goal ‘to improve the information base regarding ambient air toxics within the Australian environment in order to facilitate the development of standards …’.
The air toxics NEPM-specified monitoring and investigation levels are given in Table 3.
|Pollutant||Averaging period||Monitoring investigation level|
|Benzene||Annual average||0.003 ppm|
|Benzo(a)pyrene||Annual average||0.3 ng/m³|
|Formaldehyde||24-hour average||0.04 ppm|
|Toluene||24-hour average||1 ppm|
|Annual average||0.1 ppm|
|Xylenes||24-hour average||0.25 ppm|
|Annual average||0.2 ppm|
Source: National Environment Protection Council (2004, p. 15)
Emission data on all of these air toxics are available from the National Pollutant Inventory. Benzene emissions are dominated by motor vehicle emissions in all capital cities except for Darwin and Hobart. In Darwin, benzene emissions from bushfires (including prescribed fires) dominate, whereas in Hobart, emissions from domestic fuel burning emit almost as much benzene as motor vehicles. Except for these two cities, the reduction of benzene in petrol to a maximum of one per cent by 2006 should reduce concentrations of benzene.
Australian measurements of benzene and other air toxics (Environment Australia 2001; National Environment Protection Council 2003, pp. 28–29, 86) provide only one report of an annual average for benzene. In New South Wales, ambient levels of benzene in high traffic areas are between 0.0009 and 0.028 ppm, and in residential areas they are between 0.0004 and 0.0012 ppm.
Australia State of the Environment 2001 noted that Australia has the highest per capita number of hay fever sufferers in the world (Manins et al. 2001, pp. 89–90). A main source is ryegrass pollen—a form of pollution (in terms of human health), albeit a natural and non-gaseous contamination of the ambient air. In 2001, it was noted that, outside of Melbourne, monitoring was poor. This continues to be the case, and because of this lack of data there is no indicator for this variable.
Regional air quality issues are similar to those described for criteria pollutants for urban areas, where NEPM standards are listed. The distinctive aspects of regional air quality are the particular regional distributions, often due to localised industrial emissions, and potential consequences for agriculture and horticulture. Meteorological conditions of inland regional Australia (bushfires, daytime convective conditions and night calms) also play a distinctive role in regional air quality.
The regional air quality indicators are similar to urban indicators, but with more limited measurements that are focused on vulnerable locations from industrial emissions or wood-burning activity.
Australia’s regions have carbon monoxide levels well below NEPM standards. This is true even in the Illawarra region in New South Wales, where the largest industrial source can interact with air transported from the Sydney airshed. A slight decline, mainly at Geelong in the Port Phillip region in Victoria, may be due to reductions in refining emissions in Corio Bay. Other regional levels appear to be fairly stable, despite increasing emissions from rural burning.
Australian regions outside of urban airsheds are not significantly affected by ozone except for interregional transport of smog generated from urban emissions. The Illawarra and Lower Hunter regions in New South Wales and Latrobe Valley in Victoria are affected. Australia State of the Environment 2001 indicated the Illawarra was the main concern up to 1999, and the updated indicators have this concern persisting to 2001. One to two days per year in the Illawarra are expected to exceed NEPM standards. This is comparable with or exceeds the outer suburban sites of Rolling Green (Perth) and Helensvale (Brisbane), which are also affected by regional transport of urban smog. Regional ozone impact is also linked to bushfire incidence.
Overall, lead levels for Port Pirie, South Australia are marginally above the NEPM standard, but with excess levels at Ellen Street, which is very near the site boundary of the industrial emissions (Figure 16). The indicator levels have not changed significantly over the years 1995 to 2002, so concerns remain. Other regional centres, particularly Mount Isa (EPHC, 2004b, pp. 153–158) and Burketown in Queensland (NPI database), are subject to high emissions and are likely to exceed NEPM levels near the site of emissions, but no concentration measurements are available. Burketown in Queensland emits 36 000 kilograms of lead per year, which is just a little less than in Port Pirie (49 000 kilograms), though there are substantial year-to-year fluctuations, with emissions as high as 110 000 kilograms recorded in 2003.
Source: Environment Protection Authority, Government of South Australia, www.environment.sa.gov.au/reporting/atmosphere/pdfs/port_pirie.pdf (accessed 8 December 2004)
Nitrogen dioxide continues to be a minor concern in regions outside of urban airsheds. Like ozone, urban smog with significant levels of nitrogen dioxide can be transported to regions, but the indicators continue to show levels significantly lower than the NEPM standard, consistent with the reports in Manins et al. (2001, pp. 118–120).
Mount Isa in Queensland continues to experience one-hour daily maximum sulphur dioxide levels that exceed the NEPM. In 2001 there were 42 days with levels above the standard; however, the introduction of a sulphuric acid plant in 2001 has significantly reduced emissions, so that fewer days might now exceed the NEPM. Kalgoorlie, Western Australia, also has major emissions of sulphur dioxide, which were reduced significantly by commissioning of a sulphuric acid extraction plant in 1997. The indicator shows that air quality has improved and the NEPM standards are now close to being met. Past measurements (Manins et al. 2001, pp. 107–110) have shown Port Pirie to be outside of the NEPM standards. Current emissions at Port Pirie suggest that local air quality in some regional areas remains outside of the NEPM standards. Other regions at risk from high sulphur dioxide emissions appear to be maintaining air quality.
Regional areas have significant emissions of particles from industries, mining, domestic burning and bushfires. The indicators show monitoring at selected sites, including Lower Hunter and Illawarra in New South Wales, which are affected by industrial emissions, inland New South Wales and Western Australia, which are affected by domestic wood burning and bushfires, and industrial sites in Queensland and Western Australia (Table 4). Emissions associated with mining are generally increasing. Associated with this activity, Dampier in Western Australia has experienced conditions well outside of the PM10NEPM. Finer PM2.5 particle concentrations from wood burning activity are above the advisory reporting standard in Beresfield in the Hunter Valley, and Bunbury in inland Western Australia. Generally, semi-rural regions with high levels of domestic wood burning and frequent temperature inversions at night are expected to have poorer air quality due to fine particles.
|Albion Park NSW||61.6||63.6||48.8||62.5||58.7|
|Wagga Wagga NSW||69.8|
|South Gladstone Qld||65.2||66.7|
|NEPM 24-hour standard||50||50||50||50||50||50||50||50|
Source: DEH (data supplied direct to DEH), (2001, Table A4.41)
Launceston shows significant exceedences of the PM standard when measurements are made with a HiVol sampler. Measurements using the TEOM method are not available for Launceston. As discussed previously the TEOM method heats the sample so that volatile material is lost from the collecting filter, so the HiVol data are more representative than the TEOM data.
Benzene concentrations in regional airsheds are expected to be below urban levels because the dominant emissions are from motor vehicles, whose numbers are small in non-urban regions (Figure 17). Monitoring reported in the Australia State of the Environment 2001 indicates this to be true for the Illawarra region. The exception is the emission of benzene in the Pilbara, Western Australia. This emission is equivalent to nearly ten per cent of all motor vehicle emissions for Australia. It is likely that natural gas processing operations in the region are the source (Government of Western Australia Department of Environment 2004).
Source: NPI database, 2004–05 data
Other issues for regional air quality include odour from agricultural activity and waste treatment. The data for these, if collected, are done so at the local government or state government level, so national-level data are not available. There is also some general concern about a range of air toxics from regional industries, but there are no data available to be able to report the trends. In parts of regional Australia, bushfires will be responsible for intermittent poor air quality.
National approaches to the improvement of air quality have arisen through programmes administered through:
- the National Environment Protection Council, which operates under the umbrella of the Environment Protection and Heritage Council
- the Department of the Environment and Heritage, which includes the Australian Greenhouse Office.
Other government departments deal with specific aspects of air quality. The Department of Health and Ageing works with the enHealth council to deal with issues related to health and air quality (EnHealth Council 2005). The National Industrial Chemicals Notification and Assessment Scheme, which is also part of the Department of Health and Ageing, examines priority chemicals such as benzene, including their effects on air quality in their assessments. The Department of Transport and Regional Services deals with motor vehicle emissions.
Relevant National Environment Protection Measures are the Ambient Air Quality NEPM, the National Pollutant Inventory, the Diesel Vehicle Emissions NEPM, and the Air Toxics NEPM.
Because motor vehicles play such an important role in the emission of air pollutants , the emissions of new vehicles are controlled under Australian Design Rules (Department of Transport and Regional Services 2005). Those related to motor vehicle emissions are ADR 36, 37, 70, 79 and 80. The ability of vehicles to meet the requirements of the Australian Design Rules depends, in turn, on the fuel used in the vehicles.
The Department of the Environment and Heritage continued work on fuel quality standards that, together with complementary vehicle emission standards, are predicted to cut vehicle emissions of some pollutants by up to 60 per cent in the period 2000 to 2020. Since the Fuel Quality Standards Act 2000 came into force, fuel sulphur levels have reduced significantly. In 1999, diesel sulphur content was around 1300 ppm on average.
Under the Fuel Quality Standards Act 2000 this sulphur content was reduced to 500 ppm in December 2002, and will further reduce to 50 ppm from 1 January 2006, and to 10 ppm from 1 January 2009. Sulphur levels in premium unleaded petrol will reduce from the current level of 150 ppm to 50 ppm from 1 January 2008.
Epidemiological evidence continues to indicate that there is a relationship between particulate matter and morbidity (illness) and also, of far greater concern, between particulate matter and mortality (death rates). Numerous overseas studies, and Australian studies in Brisbane and Sydney, have confirmed such a relation. The results for Melbourne were different: in Melbourne, the statistics indicate that short-term mortality is also related to nitrogen dioxide and ozone. Removing sulphur from petrol and diesel is a first step towards reducing particulate matter emissions from motor vehicles. A woodheater replacement programme is an important step in reducing particulate matter emissions from woodheaters, which are a source of both PM10 and PM2.5 exceedences during winter in Launceston, Armidale, Canberra and parts of Melbourne. Action needs also to be taken on a number of fronts such as making woodheaters perform better (for example, through standards and auditing) and targeted education that is backed by enforcement action.
This commentary has noted that, in general, the criteria pollutants of concern in Australian capital cities are ozone and particulate matter. Other criteria pollutants seldom exceed the NEPM standards. The promulgation of lower sulphur levels in fuel in the future and the introduction of stricter motor-vehicle emission limits with ADR 79 and ADR 80 from 2006 onward are attempts to make sure that the situation remains benign. The main pressure is the continued increase in population with a concomitant increase in the number of vehicles per head of population. This means that the projections of annual vehicle kilometres travelled show a steady increase. The controls on carbon monoxide, nitrogen oxides and volatile organic compounds indicate that total motor vehicle emissions in 2020 are liable to be below those of 2006 (Figure 18), but this is unlikely to be the case with total particulate matter emissions. This is of concern because of the perceived strong links between particulate matter and mortality.
Source: Department of Transport and Regional Services, Urban Pollutant Emissions from Motor Vehicles: Australian Trends to 2020, draft June 2003, Canberra.
The conclusions of the 2001 report that are applicable to this report are that concentrations of sulphur dioxide, nitrogen dioxide and lead are not of concern in any urban area.
The favourable news for this report is that since 1998 carbon monoxide has not exceeded the NEPM standard in any Australian city, most probably as a result of vehicle emission controls that were introduced in 1997.
These vehicle emission controls appear to have been successful in stabilising maximum ozone concentrations (and thus smog concentrations) in most urban areas, but the situation in Sydney has got worse. Even for those cities where the maximum ozone concentrations have stabilised, the levels are very close to the NEPM standard, which implies that small changes in emissions (for example, an increase in vehicle numbers) or meteorological conditions (such as slightly warmer temperatures) could exacerbate smog in Melbourne, Brisbane and Perth.
Since the 2001 report, there has been increasing concern over the role of particulate matter in causing health effects. Although urban areas are within the NEPM standard, it is of concern that all four cities that report PM2.5 have had peak levels that exceed the advisory reporting standard.
There are insufficient measurements of air toxics in urban Australia, but it is to be hoped that the implementation of the air toxics NEPM will start to address this issue.
In rural and regional Australia, levels of most pollutants are well below actual or proposed standards. Sulphur dioxide emissions and lead remain a concern in a few limited localities. The data from the National Pollutant Inventory indicates that benzene may be of concern in the Pilbara. Despite the probable existence of such rural air pollution hotspots, there is insufficient monitoring to identify such hotspots on the basis of measurements, and insufficient monitoring of air toxics at such sites.
Dust and other particles, including woodsmoke, continue to be of concern in some regions and localities. The wood-heater replacement programme, which ran until June 2004, was an important step to address the issue in areas such as Launceston. A new programme is being implemented in Launceston to reduce emissions of particulates by industry. Targeted community education programmes are being run in Launceston and in parts of Hobart.
Australia has the highest per capita number of hay fever sufferers in the world, but monitoring is poor with the exception of Melbourne. Monitoring of odour is also poor.