5 Ozone
Concentrations of ozone in New Zealand have been measured in Auckland and on the outskirts of Christchurch. Results of this monitoring are compared to the following ambient air quality guideline values for New Zealand:
- 150 mgm-3 (one-hour average)
- 100 mgm-3 (eight-hour average).
The recommended monitoring method for ozone in New Zealand is AS3580.6.1 - 1990. This method specifies UV absorption. All data presented in this section are based on monitoring methods that comply with AS3580.6.1 - 1990, which is the recommended method in the Good Practice Guide for Air Quality Monitoring and Data Management (MfE, 2000) and is the required method in the Ambient Air Quality Guidelines (MfE and MoH, 2002).
5.1 Auckland
Concentrations of ozone have been measured in a number of locations in Auckland. Figure 5.1 shows the percentage of O3 concentrations measured in Pukekohe and Musick Point from 1997 to 2001. Results are within the air quality categories, however, more recent monitoring at Musick Point in 2002 (not shown on the graph) has recorded 2 exceedences of the eight-hour guideline value. The majority of the measured concentrations in these locations are between 10% and 66% of the guideline values, with less than 20% of the data within the 'alert' category. At Pukekohe the maximum eight-hour average concentration was 96 µgm-3.
Figure 5.1: Percentage of measured one-hour and eight-hour average O3 concentrations within air quality categories in Pukekohe and Musick Point, Auckland
See figure 5.1 at its full size (including
text description).
Figure 5.2 shows concentrations of O3 measured at the Skytower, Mangere and Whangaparoa within each air quality category. At the Skytower and Whangaparoa sites, the majority of the eight-hour average measurements are within the 'acceptable' category with up to 15% of the data in the 'alert' category.
Figure 5.2: Percentage of measured one-hour and eight-hour average O3 concentrations within air quality categories at the Skytower, Mangere and Whangaparoa, Auckland
See figure 5.2 at its full size (including
text description).
5.2 Christchurch
Concentrations of ozone were measured on the outskirts of Christchurch during the months January to April 1998. Sites downwind of the city were chosen to allow time, after the release of precursor emissions, for the formation of ozone to occur. The sites were at Lincoln, 20 km to the south west of the city centre, and Kainga, 13 km to the north of Christchurch. Figure 5.3 shows the percentage of O3 concentrations measured during 1998 within each air quality category. A large proportion of the eight-hour average concentrations were within the 'acceptable' category, while the one-hour average concentrations were mostly 'good' or 'excellent'. The maximum one-hour and eight-hour average concentrations at Lincoln were 97 µgm-3 and 76 µgm-3, and at Kainga, 93 µgm-3 and 75 µgm-3 respectively.
Figure 5.3: Percentage of measured one-hour and eight-hour average O3 concentrations within air quality categories at Lincoln and Kainga in Canterbury
See figure 5.3 at its full size (including text description). 