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Monitoring of CO, NO2, SO2, ozone, benzene and benzo(a)pyrene in New Zealand

Foreword

Acknowledgements

Executive Summary

1 Introduction

2 Carbon monoxide (CO)

3 Nitrogen Oxide (NOx) Emissions

4 Sulphur Dioxide (SO2)

5 Ozone

6 Benzene

7 Benzo(a)pyrene (BaP)

8 Trends in Contaminant Concentrations in New Zealand

9 Summary

References

Appendix One

About the Ministry for the Environment

2 Carbon monoxide (CO)

Concentrations of carbon monoxide have been measured in a number of urban centres in New Zealand. Results of this monitoring are compared to the following ambient air quality guideline values for New Zealand:

• 30 mgm^-3 (one-hour average)
• 10 mgm^-3 (eight-hour average).

The recommended monitoring method for carbon monoxide in New Zealand is AS3580.7.1 - 1992. This method specifies infra-red absorption. Unless stated otherwise, all data presented in this section are based on monitoring methods that comply with AS3580.7.1 - 1992. This method is the recommended in both the Good Practice Guide for Air Quality Monitoring and Data Management (MfE, 2000) and the Ambient Air Quality Guidelines (MfE and MoH, 2002).

2.1 Auckland region

Carbon monoxide concentrations have been measured at nine sites in the Auckland region since 1992. The longest record of data is for Queen Street, for which data are available from 1992 to 2000 (Tisdalls site) and from 1998 to 2001 (carpark site). The summary data for CO monitoring in Auckland is shown in Table 2.1. The percentage of measured one-hour and eight-hour average CO concentrations within air quality categories at each site is shown in the graphs in Sections 2.1.1 to 2.1.7. Site classifications for the different areas are as follows:

• Queen Street Traffic peak
• Takapuna Residential peak
• Khyber Pass Traffic peak
• Hobson Street Traffic peak
• Henderson Residential peak
• Dominion Road Traffic peak
• Pakuranga Residential peak
• Manurewa Residential neighbourhood

Descriptions of the site classifications are on page 32 of the Good Practice Guide to Air Quality Monitoring and Data Management (Ministry for the Environment, 2000). In general, the first descriptor relates to the most likely sources of pollution and the second refers to the spatial area covered by the monitoring site. The latter is described in the Australian Standard - Ambient air - Guide for the siting of air sampling units (AS 2922, 1987).

Table 2.1: Summary data for CO monitoring in Auckland

View summary data for CO monitoring in Auckland (large table)

2.1.1 Queen Street

Air quality monitoring data for CO for the years 1992 to 2000 at the Queen Street (Tisdalls) site are shown in Figure 2.1. While hourly average concentrations are typically within the 'excellent' or 'good' categories, eight-hour average concentrations are regularly in the 'acceptable' category and a small proportion of data are within the 'alert' category for most years. The eight-hour average guideline value was exceeded during the years 1992 to 1996 inclusive at the Queen Street site but was not exceeded from 1997 to 2000. The one-hour average guideline value was exceeded at this site during 1995 and reached a maximum concentration of 89 mgm^-3.

A second air quality monitoring site was established in Queen Street in 1998 (carpark site). Figure 2.2 shows the percentage of measured concentrations at this site within the air quality categories. This shows a similar trend, with the majority of the one-hour average concentrations within the 'excellent' and 'good' categories but with some eight-hour average concentrations of concern. For each of these years, between 1% and 4% of the eight-hour average data were greater than 66% of the guideline value, with a small number of guideline value exceedences occurring at this site during each of these years.

2.1.2 Takapuna

Figure 2.3 shows data for CO concentrations measured at the Takapuna air quality monitoring site. The majority of the CO concentrations measured are less than 66% of both the one-hour and eight-hour guideline values. A small proportion of the eight-hour average concentrations (less than 1%) were in the 'alert' category for the years 1995 to 1999. No guideline value exceedences for CO have been measured at this site. The maximum one-hour and eight-hour average concentrations measured were 17 and 9 mgm^-3 respectively.

2.1.3 Khyber Pass

Concentrations of CO have been measured at the Khyber Pass Road site since October 1996. The eight-hour average concentrations have exceeded the guideline value most years during the months April to August inclusive. During 1996 to 1999, over 7% of the eight-hour average concentrations were within the 'alert' air quality category. The majority of the one-hour average concentrations measured at this site were in the 'excellent' or 'good' air quality categories (Figure 2.4). The maximum one-hour and eight-hour average concentrations from 1996 to 2001 were 22 and 14 mgm^-3 respectively.

2.1.4 Hobson

Figure 2.5 shows concentrations of CO measured at the Hobson air quality monitoring site from 1995 to 2000. With the exception of one pollution episode during June 1999, CO concentrations have not exceeded the one-hour or eight-hour average guideline values. Over 80% of the measured concentrations are less than 33% of the guideline value. The maximum one-hour and eight-hour average CO concentrations measured at this site were 19 and 11 mgm^-3 respectively.

Figure 2.5: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories at Hobson, Auckland

See figure 2.5 at its full size (including text description).

2.1.5 Henderson and Dominion Road

Figure 2.6 shows the results of air quality monitoring for CO at the Dominion Road site during 1995 and 1996 and at the Henderson site from 1998 to 2001. At both sites, CO concentrations were generally within the 'excellent' or 'good' air quality categories with only a small percentage of measurements above 33% at Dominion Road during 1995. The eight-hour and one-hour average guideline values were both exceeded at Dominion Road during a pollution episode in July 1995. During this time, a maximum one-hour average concentration of 73 mgm^-3 and eight-hour average concentration of 14 mgm^-3 was recorded. The maximum one-hour and eight-hour average concentrations measured at Henderson were much lower at 20 and 5 mgm^-3 respectively.

Figure 2.6: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories at Henderson and Dominion Road, Auckland

See figure 2.6 at its full size (including text description).

2.1.6 Manurewa and Pakuranga

Concentrations of CO were measured in Manurewa in 1996 and 1997 and in Pakuranga from 1999 to 2001. No guideline value exceedences were recorded in either location and the majority of the CO concentrations were in the 'excellent' or 'good' air quality categories (Figure 2.7). The maximum one-hour and eight-hour average concentrations in Manurewa were 14 and 8 mgm^-3 and in Pakuranga, 13 and 9 mgm^-3.

2.1.7 Manukau

In addition to monitoring carried out by the Auckland Regional Council, the Manukau City Council has carried out some CO monitoring at a site in Otara. Figure 2.8 shows the majority of the CO concentrations measured at Manukau were in the 'excellent' or 'good' air quality categories.

2.2 Wellington region

Concentrations of CO have been measured in a number of locations in the Wellington region. These include the Civic Centre from March to May 1998, Huia Pool from May 1998 to May 1999, Vivian Street from May to September 1998 and the San Marino apartments from January to September 2002. The summary data for CO monitoring is shown in Table 2.2.

Figure 2.9 shows the percentage of measured one-hour and eight-hour average CO concentrations in each of the air quality categories where data was available for the sites in Wellington and Maby Road in Lower Hutt. It should be noted, however, that the data does not reflect a full calendar year of monitoring

Table 2.2: Summary data for CO monitoring in Wellington

View summary data for CO monitoring in Wellington (large table)

Concentrations of CO that exceed the eight-hour average guideline value were measured at both the Civic Centre and Huia Pool air quality monitoring sites, with the majority of the CO concentrations at the former site greater than 66% of the guideline value. Figure 2.10 shows the percentage of measured eight-hour average CO concentrations within air quality categories for each month of monitoring. This shows seasonal variations in CO concentrations at the Huia Pool site, with guideline value exceedences occurring during the months of April to July only.

Figure 2.11 shows the concentrations of CO measured at other monitoring sites in the Wellington region within the air quality categories. These data indicate concentrations are typically within the 'excellent' or 'good' air quality categories, with no guideline value exceedences or values above 66% of the guideline value in these areas.

2.3 Hamilton

Air quality monitoring for CO has been carried out at a monitoring site in Peachgrove Road, Hamilton since November 1997. Summary data for CO monitoring at this site are shown in Table 2.3. Figure 2.12 shows the majority of the measured concentrations fall within the 'excellent' air quality category and that no concentrations that are greater than 66% of the guideline value have been recorded. The maximum one-hour and eight-hour average CO concentrations measured between 1998 and 2001 were 9 and 7 mgm^-3 respectively.

Table 2.3: Summary data for CO monitoring in Hamilton

View summary data for CO monitoring in Hamilton (large table)

2.4 Northland region

Monitoring for CO was carried out in Whangarei between June and August 1994 and again during September and October 2000. The site was intended to measure peak CO concentrations at two sites, one residential and another site in the central city. The maximum one-hour average CO concentration measured during 1994 was 30.5 mg/m³ and the maximum eight-hour average concentration was 15.5 mg/m³. For the 2000 monitoring period, the maximum one-hour average CO concentration measured was 9.7 mgm^-3 and the maximum eight-hour average concentration was 6.1 mgm^-3.

2.5 Hawkes Bay region

A small amount of monitoring for CO was carried out in Napier and Hastings during the winter and spring of 1998. Summary data for this monitoring is shown in Table 2.4. Figure 2.13 shows the percentage of measured concentrations that are within the air quality categories for each month of monitoring. In Hastings, all CO measured concentrations were less than 10% of the guideline value. Higher concentrations were measured in Napier, with around 8% of the eight-hour average concentrations during July in the 'acceptable' category. No guideline value exceedences were measured at either site.

Table 2.4: Summary data for CO monitoring in the Hawkes Bay region

Figure 2.13: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories in Napier and Hastings

See figure 2.13 at its full size (including text description).

2.6 Bay of Plenty region

Monitoring of CO in the Bay of Plenty has been carried out in Rotorua and Tauranga. The summary statistics for this monitoring is shown in Table 2.5.

Figure 2.14 shows the percentage of measured concentrations within the air quality categories at the residential neighbourhood sites of Pereika Road in Rotorua and the Otumoetai Road in Tauranga. At both sites, CO concentrations are typically 'excellent' for both the one-hour and eight-hour average concentrations. Concentrations of CO have also been measured at an ambient air quality site in Opotiki during 2002. Figure 2.16 shows all concentrations measured at this site were 'excellent'.

Table 2.5: Summary data for CO monitoring in the Bay of Plenty

View summary data for CO monitoring in the Bay of Plenty (large table)

Concentrations of CO have also been measured at a traffic-peak monitoring site in both Rotorua and Tauranga. Figure 2.15 shows the percentage of CO concentrations within air quality categories measured at these sites by month. The majority of CO concentrations are 'excellent' or 'good', with a small proportion of the eight-hour average concentrations in the 'acceptable' category. No guideline value exceedences were recorded at either site.

Figure 2.15: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories in Rotorua and Tauranga traffic-peak sites

See figure 2.15 at its full size (including text description).

Figure 2.16: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories in Opotiki

See figure 2.16 at its full size (including text description).

2.7 Canterbury region

Air quality monitoring data for CO in the Canterbury region includes measurements for Christchurch from 1988, for Timaru from 1997 and shorter-term monitoring in the areas of Ashburton, Rangiora and Kaiapoi. With the exception of some peak traffic monitoring at selected sites within Christchurch, all CO monitoring sites within the region meet the residential-neighbourhood site classification. Summary data for CO monitoring for ambient air sites in the Canterbury region are shown in Table 2.6.

Table 2.6: Summary data for CO monitoring in the Canterbury region

View summary data for CO monitoring in the Canterbury region (large table)

2.7.1 Christchurch

Figure 2.17 shows the percentage of measured CO concentrations within air quality categories at the Packe Street and Coles Place monitoring sites in central Christchurch. Results indicate a large proportion of the data are within the 'excellent' or 'good' air quality categories. However, data also shows guideline value exceedences of both the one-hour and eight-hour average CO concentrations. While one-hour average guideline value exceedences are limited to during the years between 1992-1994, the eight-hour guideline value has been exceeded each year from 1988-2001 (Figure 2.18).

Figure 2.17: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories at Packe Street and Coles Place, Christchurch

See figure 2.17 at its full size (including text description).

Concentrations of CO have also been measured in other locations in Christchurch. Figure 2.19 shows the percentage of measured CO concentrations within air quality categories at Hornby and Beckenham. The majority of the CO concentrations measured at these sites were within the 'excellent' or 'good' air quality categories and no guideline value exceedences were recorded.

Figure 2.19: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories at Hornby and Beckenham, Christchurch

See figure 2.19 at its full size (including text description).

Concentrations of CO have also been measured in Christchurch at a peak traffic site in Riccarton Road in 1993, 1996 and 2001. The results of all three studies are detailed in the Environment Canterbury Report Investigations of Street Level Monitoring of Carbon Monoxide in Christchurch (Gunatilaka, 2002). The monitoring periods were June and July 1993, April to June 1996 and May to September 2001. Figure 2.20 shows the percentage of measured CO concentrations within air quality categories for these studies. Note that differences in the months sampled and in the placement of the sampler mean that the results are not directly comparable between years.

Although eight-hour average concentrations are worse relative to the air quality guideline value, exposure along Riccarton Road for this duration is less likely. The one-hour average guideline value was exceeded during both 1993 and 1996.

Figure 2.20: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories on Riccarton Road, Christchurch

See figure 2.20 at its full size (including text description).

2.7.2 Ashburton, Rangiora and Kaiapoi

Concentrations of CO measured in Ashburton (1999 to 2001), Rangiora (1999 to 2001), and Kaiapoi (2001) relative to air quality categories are shown in Figure 2.21. The majority of the CO concentrations were less than 33% of the guideline value, with less than 1% of the data being within the 'acceptable' air quality category.

2.8 Otago region

Concentrations of CO have been measured in Mosgiel in 1999 and 2000 and in Dunedin in 2002. Figure 2.22 shows the percentage of the eight-hour average CO concentrations measured in both Dunedin and Mosgiel were greater than 33% of the air quality guideline value. Both the one-hour and eight-hour average guideline values were exceeded at the latter site, with maximum-measured concentrations of 36 and 11 mgm^-3 respectively. Figure 2.23 shows the percentage of the monthly eight-hour average CO concentrations within the air quality categories for Dunedin. Some seasonal variations are apparent with higher CO concentrations measured during the winter months. During May and June 2002, about 3-4% of the CO concentrations were within the 'alert' category.

2.9 Nelson

Concentrations of CO have been measured in Nelson during both 2001 and 2002. In 2001, CO concentrations were measured at the Victory School monitoring site and at the Hospital monitoring site. Concentrations of CO at the Hospital site were 'excellent' with maximum concentrations of 9 and 5 µgm^-3 for the one-hour and eight-hour averages respectively (Figure 2.24). Maximum CO concentrations measured at Victory School were within the 'acceptable' and 'good' air quality categories for the eight-hour and one-hour averages respectively for both 2001 and 2002 (Figure 2.25). Summary data for this monitoring is shown in Table 2.7.

Table 2.7: Summary data for CO monitoring in Nelson

View summary data for CO monitoring in Nelson (large table)

Figure 2.24: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories in Nelson

See figure 2.24 at its full size (including text description).

2.10 Southland

The Ministry for the Environment undertook monitoring of CO in Invercargill and Gore for a period of one month in 1996. The maximum one-hour average CO concentrations in Invercargill and Gore were 15.0 mgm^-3 and 2.1 mgm^-3 respectively. These are both within the one-hour average guideline value of 30 µgm^-3. The maximum eight-hour average CO concentrations measured at the sites were 8.2 and 1.7 mgm^-3 respectively.

2.11 Summary of CO concentrations

In most areas of New Zealand, concentrations of CO are within the 'good' or 'excellent' air quality categories for the majority of the time. The main exceptions are found in 'traffic peak' or 'traffic dense' sites such as Khyber Pass Road in Auckland and Riccarton Road in Christchurch. In addition, concentrations of CO in excess of the guideline values have been recorded at the 'residential neighbourhood' St Albans and Hornby monitoring sites in Christchurch and at the Big Fresh monitoring site in Dunedin. Carbon monoxide concentrations have also exceeded guideline values at "traffic" sites in Auckland at Khyber Pass, Queen Street and Dominion Road, in Wellington at the Civic Centre and in Christchurch at Riccarton Road.