Report: TR04/27 (Revised edition October 2004 (Includes addendum - comment on National Environmental Standard))

Author: Emily Winton (Environet Ltd.)

Abstract

Air quality monitoring was carried out by Waikato Regional Council at a number of sites within the region during 2003. These included Hamilton, Tokoroa, Te Kuiti and Taupo. Results from these monitoring sites are presented in this report.

In Hamilton, concentrations of suspended particles (PM₁₀), carbon monoxide (CO), nitrogen dioxide (NO₂) and benzene were measured at the Peachgrove Road air quality monitoring site. In addition, benzene monitoring was carried out at a “traffic peak” monitoring site in Bridge Street. In Taupo and Te Kuiti monitoring was carried out for PM₁₀ and in Tokoroa both PM₁₀ and benzene were measured.

The main contaminant of concern at the Hamilton monitoring site was PM₁₀, with an estimated four guideline breaches occurring during 2003. The maximum measured 24-hour average PM₁₀ concentration was 62 µg m^-3, compared to a guideline of 50 µg m^-3. The annual average PM₁₀ concentration in Hamilton during 2003 was 15 µg m^-3, which is less than the annual average guideline of 20 µg m^-3. It is likely that all concentrations of PM₁₀ measured at the Hamilton monitoring site would be higher if data were adjusted for gravimetric equivalency.

Concentrations of CO measured in Hamilton during 2003 were well within air quality guidelines with most measurements falling within the “excellent” or “good” air quality indicator categories. The maximum hourly average CO concentration of 9 mg m^-3 compares to an hourly guideline of 30 mg m^-3 and the maximum 8-hour average concentration was 6 mg m^-3, half the 8-hour guideline of 10 mg m^-3. Concentrations of NO₂ were also within the guideline values of 100 µg m^-3 (24-hour) and 200 µg m^-3 (1-hour) with a maximum measured 24-hour average concentration of 34 µg m^-3 and a maximum hourly average concentration of 102 µg m^-3.

In Hamilton, benzene concentrations measured at Peachgrove Road gave an annual average concentration of 3.7 µg m^-3 compared to 5.8 µg m^-3 for the Bridge Street site. These were less than the current benzene guideline of 10 µg m^-3 but would breach the 2010 guideline of 3.6 µg m^-3.

In Tokoroa, the estimated number of guideline breaches for 24-hour average PM₁₀ was 18. The annual average PM₁₀ concentration, at 24 µg m^-3, was also in excess of the MfE guideline of 20 µg m^-3. Taupo and Te Kuiti had an estimated 12 and 5 breaches of the 50 µg m^-3 guideline, with annual average concentrations less than the 20 µg m^-3 guideline. Although benzene sampling in Tokoroa did not commence until 5 May 2003, results indicate that annual average concentrations of less than 2 µg m^-3 are likely.

All areas show similar seasonal variations in PM₁₀ concentrations, with higher values occurring during the winter months.

No clear trends in contaminant concentrations were apparent at any of the monitoring sites.

Results of air quality monitoring carried out in the Waikato Region during 2003 suggests that the proposed National Environmental Standards (NES) for PM₁₀ are likely to be breached in Tokoroa and Taupo. The proposed NES for PM₁₀ is a 24-hour average concentration of 50 µg m^-3 with an allowable 5 breaches per year. It is possible that Hamilton may also be in breach of the NES once data are adjusted for gravimetric equivalency. Further monitoring in Te Kuiti is necessary to determine ongoing compliance with the proposed NES.

Addendum to 2003 Air quality monitoring report

At the time the 2003 air quality monitoring report for the Waikato region was prepared, the Ministry for the Environment had released proposed National Environmental Standards (NES) for ambient air quality. The proposed NES described in the 2003 air quality monitoring report (Table 1.3) were made regulatory in September 2004, with one revision to the PM10 guideline. This related to the number of allowable exceedences for PM10, which was revised downwards from five in the proposed NES to one in the regulation.

In Hamilton, concentrations of carbon monoxide (CO) and nitrogen dioxide (NO2) measured during 2003 were not in breach of the NES. Concentrations of suspended particles (PM10) exceeded the standard of 50 µg m-3 (24-hour average) on three occasions. As the standard allows for only one breach per year, Hamilton would have been non-complaint with the PM10 NES had it been effective 2003.

Concentrations of ozone measured in Hamilton during the summer of 2003/ 04 have been reported separately . Results indicated no breach of the NES for ozone (150 µg m-3, 1 hour average – no allowable exceedences) would have occurred during the period from 25 November 2003 to 25 March 2004.

The NES for PM10 would have been breached in Tokoroa, Taupo and Te Kuiti in 2003, as concentrations were in excess of 50 µg m-3 on more than one occasion in each area. The number of measured exceedences in these locations for 2003 was 10, 4 and 4 respectively.

The number of exceedences reported in this addendum relate to measured PM10 concentrations only and do not include statistical extrapolations for times when monitoring was not being carried out. The latter are discussed and included in the 2003 air quality monitoring report. The NES relates to measured concentrations only and does not appear to allow for extrapolations based on missing data. All monitoring methods for PM10 were compliant with the NES specifications.

No monitoring of the other contaminants included in the ambient air quality national environmental standards was carried out in Tokoroa, Taupo or Te Kuiti. Based on monitoring carried out in other urban areas of New Zealand, it would seem unlikely that concentrations of CO, NO2 or sulphur dioxide (SO2) would exceed the NES in these locations.

Report - PDF format

Air Quality Monitoring 2003 Environment Waikato [PDF, 468 KB]