Department of the Environment and Heritage, April 2004
ISBN 0 6425 4990 7
- State of the air: National ambient air quality status and trends report 1991-2001 - Community summary (PDF - 178 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part A (PDF - 899 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part B (PDF - 1,140 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part C (PDF - 402 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part D (PDF - 2,738 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part E (PDF - 1,471 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part F (PDF - 1,269 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part G (PDF - 2,318 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Part H (PDF - 613 KB)
- State of the air: National ambient air quality status and trends report 1991-2001 - Appendices (PDF - 763 KB)
This national report describes current and historic air quality in major urban airsheds in Australia. The report presents an analysis of national air quality based on 2001 data, and examines the trends and tendencies over the past decade or so, with emphasis on the period from 1991 to 2001.
The report uses the National Environment Protection (Ambient Air Quality) Measure (AAQ NEPM) standards or advisory reporting standards as yardsticks for assessing air quality. The intention is not to assess compliance, as it is recognised that the AAQ NEPM standards did not apply over this period.
The report will enable a better assessment of air quality in Australia and comparison of air quality across major cities. It will inform decisions on air quality by jurisdictions, and provide baseline data for researchers in the field.
The report establishes a scientific baseline on which future monitoring and reporting of air quality can build, noting that monitoring and reporting in compliance with the AAQ NEPM formally commenced in 2002. In addition, the report presents comprehensive air quality statistics, establishes methods for analysis, and outlines procedures and formats for presenting annual air quality data in a nationally consistent manner. In this context, the report provides a methodology that could be adapted as a model for future national status and trends reports.
The National Environment Protection Council (NEPC), in 1998, set health-based ambient air quality standards for six pollutants, namely, carbon monoxide (CO), nitrogen dioxide (NO2), photochemical oxidants as ozone (O3), sulfur dioxide (SO2), lead (Pb) and particles as PM10. In May 2003, the NEPC varied the AAQ NEPM to include advisory reporting standards for particles as PM2.5.
In this report data provided by jurisdictions have been analysed, and NEPM-related annual statistics generated and compared against the national standards for an assessment of national air quality. The 10-year goal of the AAQ NEPM specifies that by 2008 the short-term standards for CO, NO2, O3 and SO2 can be exceeded on only one day per year, and the PM10 standard can be exceeded on only five days per year. The second-highest (for CO, NO2, O3 and SO2) or the sixth-highest (for PM10) daily maximum concentration in a calendar year therefore is used as an important indicator of assessments against the standards. In addition to the NEPM-related statistics, percentiles have been used as indicators in describing air quality and site-specific trends.
The desired environmental outcome of the AAQ NEPM is to achieve the goal as assessed in accordance with the monitoring protocol by 2008. Jurisdictions are required to report annually on progress towards achieving the goal.
In total, the report covers 79 sites where one or more of the seven AAQ NEPM pollutants are monitored. Almost all of these sites are in major urban areas, mostly in the capital cities. However, with the making of the AAQ NEPM, data from the smaller regional centres are also becoming available.
Air quality in 2001 and trends for sites for which data have been provided are summarised for each pollutant. These findings must be interpreted with care, bearing in mind the limitations of the pre-NEPM data, data availabilities and in many cases the short trend periods.
The data for 2001 have been used to prepare a model national summary of the status of air quality against AAQ NEPM standards for a given year. At a glance, in 2001, NEPM standards were exceeded only for O3, PM10 and SO2. The advisory reporting standards for PM2.5 also were exceeded. The standards and goal for CO, NO2 and Pb were met at all sites. During the last decade, there has been a dramatic downward trend in Pb and significant decreases in CO, SO2 and to a lesser extent in NO2 levels, but O3 and particle levels have remained relatively high (at or above the levels of the NEPM standards). Major urban centres, including the capital cities, are now reporting levels well below the NEPM standards for Pb, SO2, CO and NO2. Ozone, PM10 and PM2.5 are the pollutants of concern, having peak concentrations at or above the NEPM standards and no consistent downward trend.
The improvements in air quality are, to a large extent, a result of the effective implementation of regulations, in particular, of the national strategies on unleaded petrol and motor vehicle emission controls, and the advances in industrial technologies. In recent years there have been some extreme pollution events, associated with drought-related bushfires and dust storms that are outside the control of environmental agencies.
A brief pollutant-specific summary across all sites follows. In this summary, the highest of the second-highest station daily maxima is referred to as the 'highest second daily maximum'.
- The highest second daily maximum non-overlapping 8-hour concentration in 2001 is about 70% of the NEPM standard.
- Overall, the direction of trend or tendency is downward for all indicators at all sites.
- The highest second daily maximum 1-hour concentration in 2001 is close to 70% of the NEPM standard.
- Trend results do not show a consistent pattern. Although a downward trend or tendency is observed at most sites (with the biggest decrease in the early 1990s), others show an upward tendency, at least for some indicators. Nevertheless, concentration levels are low.
- The highest second daily maximum 1-hour and 4-hour concentrations in 2001 are close to 150% of the NEPM standard. Peak levels experienced by most jurisdictions are close to or above the NEPM standards.
- Trend analysis carried out at 26 sites shows results varying from jurisdiction to jurisdiction and from site to site. Although some show downward trends or tendencies, others, particularly the sites in NSW, mostly show a statistically non-significant upward tendency.
- Sulfur dioxide levels can be high at specific sites outside capital cities, such as in the industrial towns of Mt Isa and Kalgoorlie. Mt Isa reports frequent exceedences. If only the monitoring sites in capital cities are considered, the highest second daily maximum 1-hour concentration in 2001 is about 40% of the NEPM standard.
- Trends from measurements at most sites, particularly the industry-influenced sites, show decreasing concentrations over the last decade.
- The 2001 peak levels are at or below 10% of the NEPM standard.
- Monitoring data from peak sites in capital cities show a dramatic downward trend in ambient Pb levels over the last two decades.
- The 2001 peak levels are above the NEPM standard at most sites. But, only Launceston records more than the five allowable exceedences.
- Due to relatively short data periods, trend results are not conclusive. No significant trends are detected, but the tendencies appear to be mostly downward.
- The 2001 peak PM2.5 levels are above the advisory reporting standards at the four jurisdictions (NSW, Victoria, Queensland and WA) that provided data.
- Due to monitoring at a limited number of sites and the short data periods at most of these sites, trends cannot be estimated with confidence. Nevertheless, data indicate a statistically non-significant upward tendency at most of the NSW sites and at the two Queensland sites, and mostly a downward tendency in WA and Victoria.
This report has achieved a number of important milestones; in particular, it has:
- been instrumental in the generation of a database of national air quality measurements which could be extended to include future data;
- demonstrated that individual annual reports of each jurisdiction can be usefully complemented by a national analysis of the current status of air quality;
- provided site-specific estimates of trends and tendencies of air quality across the nation over the last decade. These trend analyses could be used as benchmarks for future analysis of air quality data; and
- identified data quality issues that highlight the value of national consistency being achieved through the AAQ NEPM.
These results provide a framework for future work and directions, and should assist the development of sound national and local air quality management strategies and policy responses.