Report: TR 2015/05
Author: Jonathan Caldwell
Air quality monitoring in the Waikato region focuses primarily on concentrations of PM10, the main air contaminant of concern. The National Environmental Standards for Air Quality (NESAQ) has set a maximum concentration limit for PM10 of 50 µg/m3 when averaged over 24 hours (referred to as an ambient air quality standard). The NESAQ allows for one exceedance of this standard per rolling 12 month period. More than one exceedance within a rolling 12-month period is a breach of the standard. The NESAQ requires air quality monitoring to take place in areas that are likely to exceed the standard for PM10. The 2011 amendment to the NESAQ has introduced extended timeframes for Airsheds to comply with the standard for PM10. Airsheds are split in to three categories depending on the average number of exceedances the airshed has for the previous five year period.
During 2014, concentrations of PM10 were measured by Waikato Regional Council in eight out of the region’s 20 gazetted airsheds with two stations located in the Hamilton airshed and one each in the Tokoroa, Taupo, Te Kuiti, Putaruru, Turangi, Cambridge and Te Awamutu-Kihikihi airsheds. Carbon monoxide (CO), nitrogen dioxide (NO2), benzene, toluene, ethylbenzene and xylenes and PM2.5 were also measured by Waikato Regional Council in Hamilton during 2014. This report compares contaminant concentrations measured in these airsheds to the NESAQ standards and to the Ministry for the Environment’s air quality guidelines and indicator categories.
There were two airsheds which breached the NESAQ PM10 standard over the winter of 2014.
Te Kuiti and Taupo continue to indicate a significant improvement with no exceedances recorded this year. A statistical analysis of seasonal PM10 data collected in Hamilton, Te Kuiti and Taupo indicates that concentrations have decreased over the previous six or more year period. No statistically significant change has been identified for Tokoroa and the previous decreasing trend identified for Putaruru is no longer significant based on inclusion of the 2014 data. In Hamilton, PM2.5 concentrations exceeded the World Health Organisation (WHO) guideline of 25 µg/m3 (24-hour average) on five days during 2014 and coincided with the five days when PM10 was most elevated. Concentrations of CO in Hamilton were well below the NESAQ standard of 10 mg/m3 (8-hour average) during 2014. While concentrations of NO2 in Hamilton were below the NESAQ standard of 200 µg/m3, concentrations reached just under 50% of the standard during 2014. Concentrations of benzene in Hamilton were within the national guideline of 3.6 µg/m3 and an improving or “levelling” trend is evident for annual average concentrations at all sites. The highest annual concentration was measured at the Greenwood Street monitoring site and was 2.5 µg/m3. Concentrations of toluene, ethylbenzene and xylene were also well within acceptable international criteria.
|3.1||Air quality monitoring in Hamilton||8|
|3.2||PM10 concentrations for Hamilton||9|
|3.3||Concentrations of benzene, toluene, and xylenes||17|
|3.4||Concentrations of carbon monoxide||18|
|3.5||Concentrations of nitrogen dioxide||19|
|3.6||Comparison of meteorological conditions for 2014 to previous years||20|
|3.7||Daily variations on high pollution days||22|
|4.1||Air Quality Monitoring in Tokoroa||25|
|4.2||PM10 concentrations in Tokoroa||37|
|4.3||Daily variations in PM10 and meteorology on high pollution days||30|
|5.1||Air quality monitoring in Taupo||36|
|5.2||PM10 concentrations in Taupo||37|
|5.3||Daily variations in PM10 and meteorology on high pollution days||41|
|6.1||Air quality monitoring in Te Kuiti||44|
|6.2||PM10 concentrations in Te Kuiti||45|
|6.3||Daily variations in PM10 and meteorology on high pollution days||49|
|7.1||Air quality monitoring in Putaruru||51|
|7.2||PM10 concentrations in Putaruru||52|
|8.1||Air quality monitoring in Turangi||58|
|8.2||PM10 concentrations in Turangi||58|
|9.1||Air quality monitoring in Cambridge||62|
|9.2||PM10 concentrations in Cambridge||62|
|10.1||Air quality monitoring in Te Awamutu-Kihikihi||65|
|10.2||PM10 concentrations in Te Awamutu-Kihikihi||65|