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Air GEMS/AMIS Air Quality -
Monitoring Programme: Annual Report 2008 Online version
7 Results and Discussion
7.1 Site performance and quality assurance
Monthly and annual site performance and explanations are shown in table 3, based on 10-minute averages for continuously monitored data. Per cent of valid data (V) is defined as the per cent of valid data following quality assurance adjustments. Per cent of captured data (C) is the per cent of valid data excluding calibration and maintenance.
All sampling performed at all sites was as planned during 2008. The Good Practice Guide for Air Quality Monitoring and Data Management 2009 suggests that it is difficult to reach anything close to 100 per cent valid data for long-term monitoring. Site performance has therefore been evaluated against a target of 95 per cent.
The performance of continuously monitored pollutant instruments during 2008 was generally very good, all sites had annual valid data and data capture rates greater than 95 per cent with the exception of TSP at St Albans.
Table 3: Percentage valid and capture data, 2008
7.2 Carbon monoxide (CO) 2008
CO was monitored at Greers Road, Burnside. One hour and 8-hour averages have been calculated from 10-minute averages recorded by the instrument.
Summary statistics for CO and their dates are described below.
| Site |
Maximum 1-hour average (mg/m3) |
99.9 percentile 1-hour average (mg/m3) |
Maximum 8-hour average (mg/m3) |
99.9 percentile 8-hour average (mg/m3) |
|---|---|---|---|---|
| Greers Road, Burnside | 8.7 (4 June 22:00) |
6.9 | 6.1 (21 August 03:00) |
5.2 |
Carbon monoxide results are shown in figures 7 to 11.
At Greers Road, Burnside during the 12 month period there were no exceedences of the ambient air quality 1-hour guideline (30 mg/m3) or 8-hour National Environmental Standard (10 mg/m3).
7.3 Nitrogen oxides (NO2 and NO) 2008
Oxides of nitrogen were monitored at Gavin Street, Penrose and Greers Road, Burnside. One hour and 24-hour averages have been calculated from 10-minute averages recorded by the instruments.
Summary statistics for NO2 and their dates for each site are described below.
| Site |
Maximum 1-hour average (µg/m3 ) |
99.9 percentile 1-hour average (µg/m3 ) |
Maximum 24-hour average (µg/m3 ) |
99.5 percentile 24-hour average (µg/m3 ) |
|---|---|---|---|---|
| Gavin Street, Penrose | 110.4 (10 June 09:00) |
79.9 | 57.5 (8 July) |
54.2 |
| Greers Road, Burnside | 79.7 (20 August 20:00) |
61.0 | 36.0 (20 August) |
34.0 |
Nitrogen dioxide results are shown in figures 12 to 21 (Penrose), and 22 to 31 (Burnside).
There were no exceedences of the NO2 ambient air quality 1-hour standard (200 μg/m3) or the 24-hour guideline (100 μg/m3) during 2008 at any site in Auckland or Christchurch.
7.4 Sulfur dioxide (SO2) 2008
Sulfur dioxide was monitored at Gavin Street, Penrose and Greers Road, Burnside. One hour and 24-hour averages have been calculated from 10-minute averages recorded by the instruments.
Summary statistics for SO2 and their dates for each site are described below.
| Site |
Maximum 1-hour average (µg/m3) |
99.9 percentile 1-hour average (µg/m3) |
Maximum 24-hour average (µg/m3) |
99.5 percentile 24-hour average (µg/m3) |
|---|---|---|---|---|
| Gavin Street, Penrose | 31.1 (6 May 11:00) |
23.9 | 11.8 (9 July) |
10.1 |
| Greers Road, Burnside | 70.9 (7 February 06:00) |
45.7 | 23.9 (7 February) |
16.4 |
Results for Gavin Street, Penrose are shown in figures 32 to 36 and Greers Road, Burnside is shown in figures 37 to 41. There were no exceedences of the SO2 ambient air quality 1-hour standard (350 μg/m3) or the 24-hour guideline (120 μg/m3) during 2008 at any site.
7.5 Volatile organic compounds (VOC) January–December 2008
Monitoring of VOCs was conducted at three sites, Gavin Street, Penrose, Greers Road, Burnside, and Coles Place, Christchurch. VOC monitoring utilises passive sampling badges, exposed over a three-month period. A set of results for each 2008 quarter are shown in tables 4 to 7.
The benzene guideline is 10 μg/m3 as an annual average, with an average value of 3.6 μg/m3 to be achieved by 2010. The 2008 six-month and 12-month averages are described below. The benzene annual averages from all the sites are less than the AAQG 2002 guideline and are graphed in figure 1.
| Site |
Six-month average (January–June 2008) benzene (µg/m3) |
Six-month average (July–December 2008) benzene (µg/m3) |
2008 annual average benzene (µg/m3) |
|---|---|---|---|
| Coles Place, St Albans | 1.7 | 1.1 | 1.4 |
| Greers Road, Burnside | 1.5 | 1.1 | 1.3 |
| Gavin Street, Penrose | 1.1 | 0.8 | 0.9 |
Table 4: VOC results (January–March 2008)
| January–February–March 2008 Analyte |
Limit of detection (µg/m3) |
Results (µg/m3) | ||
|---|---|---|---|---|
| Coles Place | Burnside | Penrose | ||
| Target VOCs | ||||
| Ethanol | ND | |||
| Isopropyl alcohol | ND | |||
| Acetone | ND | |||
| Pentane | 2.4 | 2.8 | ||
| Dichloromethane | ND | |||
| Butan-2-one | ND | |||
| Hexane | 0.5 | 0.5 | 1.3 | 0.8 |
| Ethyl acetate | 0.5 | 0.5 | ||
| Trichloromethane | ND | |||
| 1,1,1-trichloroethane | ND | |||
| N-butanol | ND | |||
| Benzene | 0.2 | 0.6 | 0.6 | 0.7 |
| 2-methylhexane | ND | |||
| 2,3-dimethylpentane | ND | |||
| 3-methylhexane | ND | |||
| Heptane | 0.6 | 0.9 | ||
| Trichloroethene | ND | |||
| Propyl acetate | ND | |||
| Methylcyclohexane | ND | |||
| 4-methylpentan-2-one | ND | |||
| Toluene | 0.3 | 3.6 | 3.8 | 5.3 |
| Octane | ND | |||
| Tetrachloroethene | ND | |||
| Butyl acetate | ND | |||
| Ethylbenzene | 0.3 | 0.5 | 0.5 | 0.7 |
| M+p-xylene | 0.3 | 1.9 | 1.7 | 2.8 |
| Styrene | ND | |||
| O-xylene | 0.3 | 0.7 | 0.7 | 1.0 |
| Nonane | ND | |||
| Alpha pinene | ND | |||
| Propylbenzene | ND | |||
| 1,3,5-trimethylbenzene | ND | |||
| Beta pinene | ND | |||
| Decane | ND | |||
| 1,2,4-trimethylbenzene | 0.6 | 0.7 | 1.1 | |
| Limonene | ND | |||
| Undecane | ND | |||
| Dodecane | ND | |||
| Tetradecane | ND | |||
ND = Not detected.
Table 5: VOC results (April–June 2008)
| April–May–June 2008 Analyte |
Limit of detection (µg/m3) |
Results (µg/m3) | ||
|---|---|---|---|---|
| Coles Place | Burnside | Penrose | ||
| Target VOCs | ||||
| Ethanol | ND | |||
| Isopropyl alcohol | ND | |||
| Acetone | ND | |||
| Pentane | 2.4 | 2.7 | ||
| Dichloromethane | ND | |||
| Butan-2-one | ND | |||
| Hexane | 0.5 | 1.9 | 1.7 | 1.3 |
| Ethyl acetate | 0.5 | 0.5 | ||
| Trichloromethane | ND | |||
| 1,1,1-trichloroethane | ND | |||
| N-butanol | ND | |||
| Benzene | 0.2 | 2.8 | 2.5 | 1.5 |
| 2-methylhexane | 0.6 | 0.9 | 0.7 | |
| 2,3-dimethylpentane | ND | |||
| 3-methylhexane | 0.6 | 1.1 | 0.9 | 0.6 |
| Heptane | 0.6 | 0.9 | 0.9 | |
| Trichloroethene | 0.5 | |||
| Propyl acetate | ND | |||
| Methylcyclohexane | 0.6 | 1.7 | 0.9 | |
| 4-methylpentan-2-one | ND | |||
| Toluene | 0.3 | 10.7 | 8.1 | 9.1 |
| Octane | ND | |||
| Tetrachloroethene | ND | |||
| Butyl acetate | 0.5 | 0.6 | ||
| Ethylbenzene | 0.3 | 1.7 | 1.3 | 1.4 |
| M+p-xylene | 0.3 | 5.2 | 3.9 | 4.8 |
| Styrene | ND | |||
| O-xylene | 0.3 | 2.1 | 1.6 | 1.7 |
| Nonane | 0.6 | |||
| Alpha pinene | 0.8 | 0.8 | ||
| Propylbenzene | ND | |||
| 1,3,5-trimethylbenzene | 0.6 | 0.7 | 0.6 | |
| Beta pinene | 0.8 | 1.0 | ||
| Decane | 0.7 | |||
| 1,2,4-trimethylbenzene | 0.7 | 2.4 | 1.7 | 2.0 |
| Limonene | ND | |||
| Undecane | ND | |||
| Dodecane | ND | |||
| Tetradecane | ND | |||
| Ethanol | ND | |||
ND = Not detected.
Table 6: VOC results (July–September 2008)
| July–August–September 2008 Analyte |
Limit of detection (µg/m3) |
Results (µg/m3) | ||
|---|---|---|---|---|
| Coles Place | Burnside | Penrose | ||
| Target VOCs | ||||
| Ethanol | ND | |||
| Isopropyl alcohol | ND | |||
| Acetone | ND | |||
| Pentane | 3.0 | 3.6 | ||
| Dichloromethane | ND | |||
| Butan-2-one | ND | |||
| Hexane | 0.6 | 1.0 | 1.3 | 0.9 |
| Ethyl acetate | ND | |||
| Trichloromethane | ND | |||
| 1,1,1-trichloroethane | ND | |||
| N-butanol | ND | |||
| Benzene | 0.3 | 1.8 | 1.7 | 1.0 |
| 2-methylhexane | ND | |||
| 2,3-dimethylpentane | ND | |||
| 3-methylhexane | 0.7 | 0.5 | 0.6 | |
| Heptane | 0.7 | 0.6 | 0.8 | |
| Trichloroethene | ND | |||
| Propyl acetate | ND | |||
| Methylcyclohexane | ND | |||
| 4-methylpentan-2-one | ND | |||
| Toluene | 0.3 | 5.8 | 4.9 | 6.1 |
| Octane | ND | |||
| Tetrachloroethene | ND | |||
| Butyl acetate | 0.6 | 0.5 | ||
| Ethylbenzene | 0.4 | 1.0 | 0.9 | 0.9 |
| M+p-xylene | 0.4 | 3.3 | 2.7 | 3.5 |
| Styrene | ND | |||
| O-xylene | 0.4 | 1.2 | 1.0 | 1.2 |
| Nonane | ND | |||
| Alpha pinene | ND | |||
| Propylbenzene | ND | |||
| 1,3,5-trimethylbenzene | 0.8 | 1.2 | ||
| Beta pinene | 1.0 | 0.7 | ||
| Decane | 0.9 | 0.7 | ||
| 1,2,4-trimethylbenzene | 0.8 | 2.2 | 1.0 | 1.7 |
| Limonene | ND | |||
| Undecane | 0.9 | 2.4 | ||
| Dodecane | 0.9 | 0.9 | 0.7 | 1.5 |
| Tetradecane | 0.9 | 0.8 | 0.9 | |
ND = Not detected.
Table 7: VOC results (October–December 2008)
| October–November–December 2008 Analyte |
Limit of detection (µg/m3) |
Results (µg/m3) | ||
|---|---|---|---|---|
| Coles Place | Burnside | Penrose | ||
| Target VOCs | ||||
| Ethanol | ND | |||
| Isopropyl alcohol | ND | |||
| Acetone | ND | |||
| Pentane | ND | |||
| Dichloromethane | ND | |||
| Butan-2-one | ND | |||
| Hexane | 0.6 | 0.5 | 1.0 | 0.6 |
| Ethyl acetate | ND | |||
| Trichloromethane | ND | |||
| 1,1,1-trichloroethane | ND | |||
| N-butanol | ND | |||
| Benzene | 0.3 | 0.4 | 0.4 | 0.5 |
| 2-methylhexane | ND | |||
| 2,3-dimethylpentane | ND | |||
| 3-methylhexane | ND | |||
| Heptane | 0.6 | 0.6 | ||
| Trichloroethene | ND | |||
| Propyl acetate | ND | |||
| Methylcyclohexane | ND | |||
| 4-methylpentan-2-one | ND | |||
| Toluene | 0.3 | 2.5 | 2.5 | 3.3 |
| Octane | ND | |||
| Tetrachloroethene | ND | |||
| Butyl acetate | ND | |||
| Ethylbenzene | 0.4 | 0.4 | 0.4 | 0.5 |
| M+p-xylene | 0.4 | 1.3 | 1.1 | 1.8 |
| Styrene | ND | |||
| O-xylene | 0.4 | 0.4 | 0.4 | 0.6 |
| Nonane | ND | |||
| Alpha pinene | ND | |||
| Propylbenzene | ND | |||
| 1,3,5-trimethylbenzene | ND | |||
| Beta pinene | ND | |||
| Decane | 0.8 | 0.6 | ||
| 1,2,4-trimethylbenzene | 0.8 | 0.8 | ||
| Limonene | ND | |||
| Undecane | 0.8 | 1.2 | ||
| Dodecane | ND | |||
| Tetradecane | ND | |||
ND = Not detected.
Figure 1: MfE benzene annual average 2008
Annual average benzene results at all the sites were within both the current ambient air quality guideline of 10.0 mg/m3 and the future guideline value of 3.6 mg/m3 (effective 2010).
7.6 Particulate matter (PM10) 2008
PM10 is monitored at Gavin Street, Penrose and Greers Road, Burnside, using Thermo FH62-C14 BAM. Twenty-four hour averages have been calculated from 10-minute averages recorded by the instruments. All PM10 concentrations are reported at standard temperature and pressure (0°C and 101.3 kPa).
Summary statistics for PM10 and their dates for each site are described below.
| Site |
Maximum 24-hour average (µg/m3) |
99.5 percentile 24-hour average (µg/m3) |
|---|---|---|
| Gavin Street, Penrose | 41 (29 February) |
38 |
| Greers Road, Burnside | 68 (30 May) |
64 |
There were no exceedences of the ambient air quality standard (50 µg/m3) in Auckland during the 12 month period. PM10 for 2008 for Penrose are shown in Figures 42 to 44.
At Greers Road, Burnside, there were 11 exceedences of the 24-hour standard. Each exceedence and the date are listed in table 8 below. PM10 for 2008 for Burnside are shown in figures 45 to 47. As there were exceedences at the Christchurch site, more data analysis was carried out in section 7.9. All exceedences occurred over the winter period, a time when wood burning is widely used for domestic heating. Cold winter conditions strongly influence air pollution in the region especially in calm conditions. All 12 exceedences occurred in cooler months between mid May and August 2008.
Table 8: Greers Road, Burnside PM10 exceedences of the daily NES 2008
| Date |
Burnside PM10 (µg/m3) |
|---|---|
| 15/05/2008 | 64 |
| 28/05/2008 | 60 |
| 29/05/2008 | 64 |
| 30/05/2008 | 68 |
| 04/06/2008 | 54 |
| 10/06/2008 | 53 |
| 20/06/2008 | 51 |
| 21/06/2008 | 52 |
| 25/06/2008 | 52 |
| 16/08/2008 | 51 |
| 20/08/2008 | 65 |
Note: National Environmental Standard for PM10 = 50 µg/m³.
7.7 Total suspended particulates (TSP) 2008
TSP is measured as a seven-day average at Gavin Street, Penrose and Coles Place, St Albans. Maximum results and their dates (seven-day ending period) for each site are described below.
| Site | Maximum seven-day average (µg/m3) |
|---|---|
| Gavin Street, Penrose | 27 (19 March) |
| Coles Place, St Albans | 26 (21 August) |
There were no exceedences of the Ministry of Health (MoH) guideline of 60 μg/m3 at any site. The TSP concentrations in Auckland are shown in figures 2 and 3 while Christchurch TSP concentrations are shown in figures 4 and 5.
Figure 2: Auckland TSP seven-day average 2008
All seven-day TSP results at the Penrose site were within the Ministry of Health guideline of 60 mg/m3. Peak levels occurred from March to May 2008.
Figure 3: Auckland TSP seven-day average 1994–2008
The Penrose site has shown a downward trend over this period despite yearly fluctuations in seven-day TSP levels. TSP levels at this site have only exceeded the Ministry of Health guideline (60 mg/m3) in 1996 and 1999.
Figure 4: Christchurch TSP seven-day average 2008
Values remained below the Ministry of Health guideline throughout the year. Peak seven-day TSP levels occurred in June and August.
Figure 5: Christchurch TSP seven-day average 2002–2008
Data for the Burnside site shows the same seasonal variations each year, with peak levels occurring in June. Peak levels have, however, shown a downward trend. June 2008 TSP levels were the lowest for this period since 2002.
7.8 Lead (Pb) June–August 2008
Lead is measured from seven-day averaged TSP samples to derive a three-month average at Gavin Street, Penrose and Coles Place, St Albans. The results are described in the table below. Figure 6 provides moving three-month averaged lead data between January 1996 and September 2000 when lead monitoring was performed on a monthly basis. From this point lead continued to be monitored over a three-month period (June to August) annually.
| Site | June 2008 average (µg/m3 ) | July 2008 average (µg/m3 ) | August 2008 average (µg/m 3 ) | Winter 2008 average (µg/m3 ) |
|---|---|---|---|---|
| Gavin Street, Penrose | 0.007 | 0.009 | 0.003 | 0.007 |
| Coles Place, St Albans | 0.025 | 0.016 | 0.016 | 0.019 |
No site exceeded the three-month average guideline for lead (0.2 μg/m3).
Figure 6: MfE lead three-month average results 1996–2008
All Lead results were within the ambient air quality guideline of 0.2 mg/m3. The 3-month average levels in winter from 2003 to 2008 did not exceed 0.05 mg/m3.
Figure 7: MfE Burnside CO 1-hour fixed average January–December 2008
All carbon monoxide results at the Burnside monitoring site were within the 30 mg/m3 ambient air quality guideline. Peak levels in June were all below 10 mg/m3.
Figure 8: MfE Burnside CO 1-hour fixed average 2003–2008
Annual variations in carbon monoxide levels were similar for all six years. The highest result for the period was less than half of the ambient air quality guideline of 30 mg/m3.
Figure 9: MfE Burnside CO 8-hour rolling average January–December 2008
All carbon monoxide (CO) 8-hour average results were within the national environmental standard for CO (10 mg/m3) in 2008. Data shows two annual peaks occurring in June and September. Results were lowest during the first and fourth quarters of the year.
Figure 10: MfE Burnside CO 8-hour rolling average 2003–2008
The national environmental standard for carbon monoxide (CO) was only exceeded in 2006. Peak CO levels slightly increased in 2008 but this was lower than peak levels from 2003 to 2006.
Figure 11: MfE Burnside CO annual average 2003–2008
Although carbon monoxide (CO) annual average results fluctuated, 2008 results were lower than 2003 levels. The highest annual average was in 2006 while the lowest was in 2005.
Figure 12: MfE Penrose NO2 1-hour fixed average January–December 2008
The national environmental standard for nitrogen dioxide was not exceeded at the Penrose site in 2008.
Figure 13: MfE Penrose NO2 1-hour fixed average 1997–2008
The national environmental standard for nitrogen dioxide was only exceeded once (2005) in the twelve years from 1997 to 2008.
Validation of results in 2008 showed that NO2 exceedences in 2001 were due to instrumentation error. These results have been considered invalid and removed from the data set.
Figure 14: MfE Penrose NO2 24-hour fixed average January–December 2008
All nitrogen dioxide daily results at the Penrose site were within the ambient air quality guideline of 100 µg/m3.
Figure 15: MfE Penrose NO2 24-hour fixed average 1 January 1997–2008
Nitrogen dioxide daily averages showed very similar annual trends from 1997 to 2008 with peaks occurring in June. There were no exceedences of the ambient air quality guideline in the past 12 years.
Figure 16: MfE Penrose NO2 annual average 1997–2008
There was little change in annual nitrogen dioxide levels from 1997 to 2008. The highest annual average was in 2001 while the lowest was in 1998.
Figure 17: MfE Penrose NO2 and NO 1-hour fixed average January–December 2008
NO levels appear to display a greater degree of variation throughout the year compared to NO2. Peak NO levels occurred in May and June.
Figure 18: MfE Penrose NO2 and NO 24-hour fixed average January–December 2008
The range of NO results reflect the same trend as that of figure 17. NO levels during most of the year were generally below 70 µg/m3 except for peaks from April to July.
Figure 19: MfE Penrose NO 1-hour fixed average 1997–2008
Annual NO (1-hour average) variations are similar from 1997 to 2008 with peak levels occurring in June. Peak levels have significantly decreased from over 1000 µg/m3 in 1997 to below 600 µg/m3 in 2008.
Figure 20: MfE Penrose NO 24-hour fixed average 1997–2008
Daily NO levels follow the hourly trend in figure 19. The highest daily NO result was in 1997.
Figure 21: MfE Penrose NO annual average 1997–2008
The downward trend shown in figures 18 and 19 is more clearly seen in the annual NO levels for the past 12 years. The annual NO level in 2008 is less than half of 1997 levels.
Figure 22: MfE Burnside NO2 1-hour fixed average January–December 2008
All hourly NO2 results in Burnside were below the national environmental standard of 200 μg/m3. No result was above 80 μg/m3 at the Burnside monitoring site.
Figure 23: MfE Burnside NO2 1-hour fixed average 2003–2008
No exceedence of the national environmental standard occurred from 2003 to 2008 at the Burnside site. All hourly NO2 results were less than half of the standard.
The national environmental standard for NO2 is 200 µg/m3.
Figure 24: MfE Burnside NO2 24-hour fixed average January–December 2008
The daily NO2results for 2008 were all within the ambient air quality guideline of 100 µg/m3 at the Burnside site. NO2 levels were slightly higher from May to September. All results were below 40 µg/m3, which is less than half the guideline value.
Figure 25: MfE Burnside NO2 24-hour fixed average 2003–2008
Daily NO2levels in the past six years were all below the ambient air quality guideline of 100 µg/m3. The highest daily NO2 average in Burnside occurred in the winter of 2005. Results from 2008 show a similar yearly trend of elevated levels from May to September.
Figure 26: MfE Burnside NO2 annual average 2003–2008
NO2 annual levels in Burnside show a similar trend as that of the daily NO2 levels. 2005 had the highest annual NO2 average while 2008 had the lowest annual average NO2 for the past six years.
Figure 27: MfE Burnside NO2 and NO 1-hour fixed average January–December 2008
The hourly NO levels in Burnside peak in June and are lowest during the months of January and December. Hourly NO2 levels have less variation during the year than hourly NO levels.
Figure 28: MfE Burnside NO2 and NO 24-hour fixed average January–December 2008
The daily NO averages in Burnside have a greater degree of variation during the year, reflecting the hourly trend in figure 27. Daily NO results also peaked in June while daily NO2 levels peaked in August.
Figure 29: MfE Burnside NO 1-hour fixed average 2003–2008
Annual NO (1-hour average) variations in Burnside were similar from 2003 to 2008 with the highest result obtained in 2006. The second highest hourly average NO was recorded in 2007. All other years had similar hourly NO levels.
Figure 30: MfE Burnside NO 24-hour fixed average 2003–2008
Daily NO levels in Burnside follow the hourly trend in figure 29. The highest daily NO result was in 2006.
Figure 31: MfE Burnside NO annual average 2003–2008
The annual average NO at Burnside had a slightly increasing trend from 2003. This peaked in 2006 and from there began a decreasing trend to 2008. Annual average NO in 2008 was slightly higher than the 2003 average.
Figure 32: MfE Penrose SO2 1-hour fixed average January–December 2008
There was no exceedence to the national environmental standards for SO2 in 2008. Hourly SO2 levels at Penrose were all below 50 µg/m3. The national environmental standard for SO2 is 350 µg/m3.
Figure 33: MfE Penrose SO2 1-hour fixed average 2003–2008
The hourly SO2 levels at Penrose for the past six years have relatively been within the same range. Peaks occurred in 2005 but these were below 60 µg/m3. The national environmental standard for SO2 of 350 µg/m3 has not been exceeded from 2003 to 2008.
Figure 34: MfE Penrose SO2 24-hour fixed average January–December 2008
All daily SO2 results at Penrose were below the ambient air quality guideline of 120 µg/m3. Daily SO2 results from May to July were slightly higher than other months. Results from August to December were very low (less than 10 µg/m3).
Figure 35: MfE Penrose SO2 24-hour fixed average 2003–2008
The daily SO2 levels at the Penrose site were all below the ambient air quality guideline of 120 µg/m3. The peak daily level SO2 was recorded in 2005. No daily result was above 20 µg/m3 for the past six years.
Figure 36: MfE Penrose SO2 annual average 2003–2008
The annual average SO2 at Penrose had an increasing trend from 2003. This peaked in 2005. There was a significant decrease in annual SO2 levels in 2006. This was followed by a slightly decreasing trend in 2007 and 2008. Annual average SO2 in 2008 was lower than the 2003 average.
Figure 37: MfE Burnside SO2 1-hour fixed average January–December 2008
All hourly SO2 results at Burnside were within the national environmental standard of 350 µg/m3 in 2008. There were elevated results in January and February but these were less than 100 µg/m3. Hourly SO2 results for the rest of the year were below 50 µg/m3.
Figure 38: MfE Burnside SO2 1-hour fixed average 2003–2008
The national environmental standard for SO2 was not exceeded from 2003-2008 at the Burnside site. The highest hourly SO2 average was recorded in 2003. This was the only result that exceeded 100 µg/m3. Most of the hourly results for the other years were below 50 µg/m3.
Figure 39: MfE Burnside SO2 24-hour fixed average January–December 2008
No daily SO2 average at Burnside was above the ambient air quality guideline of 120 µg/m3. All results were below 30 µg/m3.
Figure 40: MfE Burnside SO2 24-hour fixed average 2003–2008
There was a similar yearly trend in daily SO2 levels at Burnside for the past six years. Most of the daily SO2 results were below 20 µg/m3 with peaks occurring in 2003 and 2006.
Ambient air quality guideline for SO2 – 120 µg/m3
Figure 41: MfE Burnside SO2 annual average 2003–2008
The highest annual average SO2 at Burnside was in 2003. There have been fluctuations in annual averages in the past six years. Results were similar from 2003 to 2005 then decreased in 2006 and 2007. There was then an increase in annual average SO2 in 2008. The lowest annual average was in 2007.
Figure 42: MfE Penrose PM10 24-hour fixed average January–December 2008
All daily PM10 levels were below the national environmental standard of 50 µg/m3. There were slightly elevated PM10 levels in March, May, June and July. Daily PM10 levels from August to December were below 30 µg/m3.
Figure 43: MfE Penrose PM10 24-hour fixed average 2003–2008
All daily PM10 results from 2003 to 2008 were below the national environmental standard of 50 µg/m3.
Figure 44: MfE Penrose PM10 annual average 2003–2008
All annual average PM10 levels from 2003 to 2008 were below the ambient air quality guideline of 20 µg/m3. The lowest annual average at Penrose was recorded in 2005 while the highest was in 2003.
Figure 45: MfE Burnside PM10 24-hour fixed average January–December 2008
There were 11 exceedences of the national environmental standard for daily PM10 at the Burnside site in 2008. These occurred from May to August. The exceedences ranged from 51 (June and August ) to 68 µg/m3 (May).
National environmental standard for PM10 – 50 µg/m3.
Figure 46: MfE Burnside PM10 24-hour fixed average 2003–2008
There have been yearly exceedences of the national environmental standard for PM10 at the Burnside site from 2003 to 2008. The highest daily value was recorded in 2006. Daily PM10 results in 2006 and 2007 had peak levels more than double the PM10 standard of 50 µg/m3.
Figure 47: MfE Burnside PM10 annual average 2003–2008
Annual average PM10 in 2003 and 2004 were above the ambient air quality guideline of 20 µg/m3. Results from 2005 to 2008 were all below the guideline value with 2007 recording the lowest annual average PM10 at Burnside.
7.9 Analysis of exceedences
7.9.1 Exceedences at Greers Road, Burnside
The only exceedences recorded during 2008 were at Greers Road, Burnside, for PM10 daily averages. All the other parameters monitored at all sites were below the national environmental standards (NES) for air quality.
Time of year
The PM10 standard of 50 µg/m3 was exceeded 11 days in 2008 during the cooler months from May to August. During May there were three consecutive days that incurred exceedences (28–30 May). During June there were two consecutive days that incurred exceedences (20–21 June).
Time of day
The typical diurnal trend in PM10 during winter is shown in figure 48. Here PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 are plotted against time of day. From figure 48, the biggest contributions to PM10 were between the hours of 18:00 and 03:00. This would suggest contributions from wood burning for home heating.
Temperature
Figures 49, 50 and 51 plot PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 against hourly average temperature measured at 1.5 m, hourly average temperature measured at 10 m, and the difference between the hourly averages of the two temperature heights. From figure 49, the biggest contributions to PM10 were when temperature measured at 1.5 m was below 10°C. From figure 50, the biggest contributions to PM10 were when temperature measured at 10 m was below 12°C. From figure 51, the biggest contributions to PM10 were when temperature difference between 10 m and 1.5 m was greater than zero, ie, when temperature inversion conditions prevailed. This is consistent with the trapping of pollutants and subsequent higher concentrations expected during temperature inversion conditions.
Relative humidity
Figure 52 plots PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 against hourly average relative humidity (RH). From figure 52, contribution to PM10 began when RH was above 60 per cent and peaked at around 90 per cent, ie, high RH conditions. This is consistent with diurnal RH and temperature patterns throughout the day.
Wind direction
Figure 53 plots PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 against hourly average wind directions. From figure 53, no wind direction seems to contribute significantly higher concentrations than others. This is consistent with an area wide diffuse (as opposed to point/line) source of pollution. There were very few data points in the sector 120 degrees to 180 degrees as wind frequency from this sector is usually low.
Wind speed
Figure 54 plots PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 against hourly average wind speeds. From figure 54, contributions to PM10 began when wind speed was below 1.5 m/s and peaked at a wind speed of 0.5 m/s, ie, low wind speed conditions. This is consistent with reduced dispersion under low wind speed conditions.
NO
Figure 55 plots PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 against hourly average NO. From figure 55, a positive linear relationship seems to exist between PM10 and NO concentrations. This relationship is more defined at PM10 concentrations below 60 μg/m3 and NO concentrations below 80 μg/m3. This is expected as PM10 and NO is co-generated during the burning of wood and fossil fuels.
CO
Figure 56 plots PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 against hourly average CO. From figure 56, a positive linear relationship seems to exist between PM10 and CO concentrations. This relationship is more defined at PM10 concentrations below 60 μg/m3 and CO concentrations below 2.5 µg/m3. This is expected as PM10 and CO is co-generated during the burning of wood and fossil fuels. This is also expected due to meteorological conditions during winter.
SO2
Figure 57 plots PM10 hourly averages for those days where the daily PM10 average exceeded 50 μg/m3 against hourly average SO2. From figure 57, the relationship between PM10 and SO2 concentrations seems to depend on the exceedence day. On a few days there seems to be a positive trend although this is probably due to meteorological conditions.
Conclusions
From the comparisons of available meteorological parameters and other pollutants as discussed above, it can be concluded that the PM10 exceedences were most likely due to home heating during the colder months, especially in the evenings, worsened by temperature inversions trapping the pollutants and low wind speed conditions preventing effective dispersion of pollutants.
Figure 48: MfE Burnside PM10 vs time of day
The biggest contributions to PM10 in 2008 were between the hours of 18:00 and 03:00 peaking at around 21:00.
Figure 49: MfE Burnside PM10 vs 1.5 m temperature
The biggest contributions to PM10 in 2008 were when temperature measured at 1.5 m was below 10oC.
Figure 50: MfE Burnside PM10 vs 10 m temperature
The biggest contributions to PM10 were when temperature measured at 10 m was below 12oC.
Figure 51: MfE Burnside PM10 vs temperature difference 10 m–1.5 m
The biggest contributions to PM10 were when the temperature difference between 10 and 1.5 metres was greater than zero. This is when temperature inversions occur.
Figure 52: MfE Burnside PM10 vs relative humidity
This figure shows that PM10 began increasing when the relative humidity was above 60 per cent and peaked at around 90 per cent.
Figure 53: MfE Burnside PM10 vs wind direction
No wind direction seemed to contribute significantly higher PM10 levels than others. There were very few data points from 120 to 180 degrees as wind frequency from this sector is usually low.
Figure 54: MfE Burnside PM10 vs wind speed
The figure shows that contributions to PM10 began when wind speed was below 1.5 m/s and peaked at a wind speed of 0.5 m/s.
Figure 55: MfE Burnside PM10 vs NO
A positive linear relationship seems to exist between PM10 and NO levels. This relationship is more defined at PM10 levels below 60 µg/m3 and NO levels below 80 µg/m3.
Figure 56: MfE Burnside PM10 vs CO
A positive linear relationship seems to exist between PM10 and CO levels. This relationship is more defined at PM10 levels below 60 µg/m3 and CO levels below 2.5 mg/m3.
Figure 57: MfE Burnside PM10 vs SO2
The figure shows that the relationship between PM10 and SO2 concentrations seems to depend on the exceedence day. On a few days there seems to be a positive trend although this is probably due to meteorological conditions.
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