Compliance with air quality standards

Background

• Background
• Particulate matter less than 2.5 micrometres in size (PM2.5)
• Impact of wood heaters on air quality
• Particulate matter less than 10 micrometres in size (PM₁₀)
• Ozone
• Carbon monoxide CO
• Nitrogen dioxide NO₂

Measuring air quality in the ACT

The ACT’s air quality monitoring network has only two National Environment Protection (Ambient Air Quality) Measure (AAQ NEPM) compliant monitoring stations at Monash and Florey. The Monash station is situated in the Tuggeranong Valley, the Florey station in Belconnen (Figure A2). A third station at Civic does not satisfy AAQ NEPM compliance requirements and is not reported here. The Florey station was established in February 2014 to comply with AAQ NEPM monitoring requirements for the ACT’s growing population. 

A2: Air quality monitoring stations in the ACT

The National Environment Protection Council (NEPC) sets ambient air quality reporting standards and goals through the AAQ NEPM. This AAQ NEPM prescribes targets for pollutants in ambient air, as well as the methods that should be used to monitor the pollutants. The ACT EPA reports annually against the AAQ NEPM standards and goals. Compliance with the AAQ NEPM standards ensures that the ACT is achieving the national environment protection standards for ambient air quality and that monitoring of AAQ NEPM pollutants is being undertaken appropriately.

The pollutants included in the AAQ NEPM are: 

• carbon monoxide (CO) 
• lead 
• nitrogen dioxide (NO₂) 
• ozone 
• sulfur dioxide 
• particulate matter less than 10 micrometres in size (PM₁₀) 
• particulate matter less than 2.5 micrometres in size (PM_2.5). 

The ACT monitors the levels of CO, NO₂, ozone, PM₁₀ and PM_2.5 in ambient air. The ACT does not monitor sulfur dioxide due to the lack of heavy industry in the region, and lead levels have not been monitored since the phase-out of leaded petrol in 2002.

To comply with the AAQ NEPM, the ACT Government must demonstrate that air quality meets the specified standards (Table A1). The PM_2.5 standard came into effect in February 2016. Before this date, the PM_2.5 standard was advisory only. For PM₁₀, the ACT Government has set a lower annual standard of 20 μg/m³, as opposed to the NEPM standard of 25 μg/m³. Poor air quality arising from fire (both unplanned and controlled burns), or pollution events such as dust storms, are excluded from AAQ NEPM compliance assessments. 

Table A1: National Environment Protection (Ambient Air Quality) Measure standards and goals

Notes: μg/m³ = micrograms per cubic metre; PM_2.5 = particulate matter less than 2.5 micrometres; PM₁₀ = particulate matter less than 10 micrometres; ppm = parts per million.

Information on air quality monitoring and annual results can be found in the ACT Air Quality Reports.Environment Protection Authority, 2019, ACT Air Quality Report 2018, ACT Government, Canberra.

Condition and trends

The concentration of air pollutants depends on several factors, including the rate of emissions, the weather and the topography of the area. For example, wood smoke levels are more pronounced in winter in the Tuggeranong Valley than in other areas of the ACT largely because of the topography of the area. These factors need to be taken into account when interpreting monitoring results.

Particulate matter less than 2.5 micrometres in size (PM_2.5)

Because the PM_2.5 standard came into effect in February 2016, all prior exceedances for PM_2.5 are for the advisory standard only. However, there is no difference between the previous advisory standard and the current PM_2.5 standard, so all annual exceedances are comparable regardless of reporting year. 

There were 31 exceedances of the daily AAQ NEPM standard for PM_2.5 recorded over the reporting period (2015 to 2018). This included: 

• 28 exceedances for the Monash station – 6 in 2015, 8 in 2016, 12 in 2017, and 2 in 2018 (Figures A3 and A4). 
• Three for the Florey station – 1 in 2016, 2 in 2018 (Figure A4).

These results show that PM_2.5 pollution is far more likely in the Tuggeranong Valley. In addition, exceedances have occurred at the Monash station in every year since 2009. 

For the Monash station between 2015 and 2018, there were 23 exceedances due to smoke from wood heaters, 4 from controlled burns and 1 from a dust storm event (Figure A4). For the Florey station, there was one exceedance due to smoke from wood heaters, one from controlled burning, and one from a dust storm event. Natural events such as dust storms, controlled burns and bushfires, which cannot be controlled through normal air quality management programs, are not included in the assessment of AAQ NEPM standard compliance.

Results for annual average PM_2.5 levels for the Monash station and the Florey station are both compliant with the AAQ NEPM standard of 8 μg/ m³ (Figure A5). However, the annual average levels recorded for Monash station over the reporting period were between approximately 85% and 96% of the standard. For Florey, annual average levels were between approximately 81% and 93% of the standard. This shows that whilst PM_2.5 levels are within the AAQ NEPM standard, they are closer to exceeding the annual standard than for other monitored pollutants. 

Overall, results show no long-term trends in PM_2.5 levels. High levels and annual variations are likely due to the occurrence of calm autumn and winter days which increase the accumulation of urban pollution from wood heaters. 

It is clear that PM_2.5 is the most serious air quality issue for the ACT with levels that are likely to have health implications for sensitive individuals.

Impact of wood heaters on air quality

The replacement of wood heaters with energy efficient electric heating is critical to improving air quality in the ACT, particularly in the Tuggeranong Valley. Wood heaters were responsible for 82% of the daily PM_2.5 exceedances from the Monash station between 2015 and 2018. Seasonal averages for the Monash station clearly show the impact of wood heaters on PM_2.5 levels (Figure A6). During the late autumn and winter months, PM_2.5 levels were elevated in response to peak wood heater usage.

Particulate matter less than 10 micrometres in size (PM₁₀)

There were 8 exceedances of the daily AAQ NEPM standards for PM₁₀ recorded during the reporting period. This included 4 exceedances for the Monash station in 2018, and 4 exceedances for the Florey station (1 in 2015 and 3 in 2018). All of the exceedances were due to dust storms. Natural events such as dust storms, controlled burns and bushfires, which cannot be controlled through normal air quality management programs, are not included in the assessment of AAQ NEPM standard compliance. With the exclusion of dust storms, results for PM₁₀ are compliant with the AAQ NEPM standard for both the Monash and Florey stations. 

Overall, results show no long-term trends in PM₁₀ levels, with events such as dust storms, controlled burns and bushfires responsible for increased levels.

Ozone

There were no exceedances of the daily maximum 1-hour and 4-hourly AAQ NEPM standards for ozone recorded during the reporting period for both the Monash and Florey stations. Despite this, 4-hourly maximum levels recorded for Monash station during the reporting period were between approximately 60% and 70% of the standard. Such levels may have health implications for sensitive individuals. Maximum results for the Florey station are also similar, with the exception of 2015 which was lower than Monash.

Overall, results show no long-terms trends in ozone levels, with annual variations in maximum concentrations likely due to hazard reduction burns in the region.

Carbon monoxide CO

There were no exceedances of AAQ NEPM standards for CO recorded during the reporting period for both the Monash station and the Florey station. All levels recorded were well within the compliance range. There was also little difference in CO levels between the stations.

Overall, CO levels appear to be slightly declining, likely due to improvements in vehicle emissions which are the main source of CO pollution in the ACT.

Nitrogen dioxide NO₂

There were no exceedances of AAQ NEPM standards for NO₂ recorded during the reporting period for either the Monash or Florey stations. All levels recorded were well within the compliance range. There was also little difference in NO₂ levels between the stations.

Overall, results show that NO₂ levels appear to be stable, with some slight annual variations in maximum concentrations.