New Zealand's air quality still fails to meet standards, even after 5 year extension
New Zealand's National Environmental Standards for Air Quality were introduced in 2004. Regional Councils were given responsibility to make sure air met those standards by 2011. After some years it became clear that that target date was not going to be met. So the regulations were amended, and Councils were given until September 2016.
So, as of last week at least 18 "airsheds" (i.e. towns or cities) were in breech of the standard for particulate matter (PM10), according to monitoring data collected by Councils and posted on the national environmental data website (www.lawa.org.nz), with 4 more at risk of breaching the standard before the winter is over.
The standard is based on the daily average level of airborne particulates, PM10. A daily average above 50 micrograms per cubic metre is termed an 'exceedence'. Each town is permitted a single exceedence per year, mainly to allow for atypical events like Guy Fawkes night or freak meteorological events. After that the airshed is in "breech". A handful of "hard case" airsheds are allowed three exceedences per year up until 2020.
The list of 17 offending airsheds will hold no surprises for those of us used to looking at air quality data. It does not include most of our major cities - Auckland ,Wellington, Hamilton, Dunedin, Tauranga. Of the 18, 6 are in Otago. Airsheds in Otago have already recorded more exceedences than all of the rest of the country added together. This year's highest daily PM10 concentration so far was recorded in the tiny Otago town of Milton at 154 micrograms per cubic metre - three times the standard.
As reported in our previous post, our current study town of Rangiora has experienced two exceedences of the standard so far this winter.
So what's going on? Each town, and its responsible Regional Council, has had nearly 13 years to meet these targets, including one deadline extension. And why, particularly, Otago?
Overwhelmingly, those towns with the most stubborn air quality problem are also those where air pollution is dominated by woodsmoke from home heating. They are also towns with cold winters and good access to wood. They also tend to be towns with a low population turnover and therefore relatively lower rates of property sales. The inland Otago towns also tend to have more low winds than many other locations because of their valley geography and absence of sea breezes.
Some of this year's offending towns, although they are in breech of the standard this year, are at least still on a downward trend and may comply with the standard at some point in the future. But others are making little progress or are nowhere near compliance. These towns really need a serious re-think, a "Plan B".
But, when seen through from the point of view of the CONA project we also find ourselves asking: How much is the state of compliance or breech dependent upon where the monitoring site has been placed? We've recently shown how Rangiora's monitoring site appears to be in more-or-less the most polluted part of town - as required by the regulations. That was a combination of good judgement and luck on the part of Environment Canterbury. But, if chance had led ECan to select a site a few hundred metres away, the air quality record have been quite different, with (perhaps) the town probably declared to have met the standard some time ago. It is quite plausible that in some other towns we will find the opposite situation - where the official council air quality monitoring site is actually under-representing concentrations in the town and that air quality elsewhere in the town is actually worse than what the monitoring sits says; that the site says the town complies with the standard when actually it does not.
Time will tell....
So, as of last week at least 18 "airsheds" (i.e. towns or cities) were in breech of the standard for particulate matter (PM10), according to monitoring data collected by Councils and posted on the national environmental data website (www.lawa.org.nz), with 4 more at risk of breaching the standard before the winter is over.
The standard is based on the daily average level of airborne particulates, PM10. A daily average above 50 micrograms per cubic metre is termed an 'exceedence'. Each town is permitted a single exceedence per year, mainly to allow for atypical events like Guy Fawkes night or freak meteorological events. After that the airshed is in "breech". A handful of "hard case" airsheds are allowed three exceedences per year up until 2020.
The list of 17 offending airsheds will hold no surprises for those of us used to looking at air quality data. It does not include most of our major cities - Auckland ,Wellington, Hamilton, Dunedin, Tauranga. Of the 18, 6 are in Otago. Airsheds in Otago have already recorded more exceedences than all of the rest of the country added together. This year's highest daily PM10 concentration so far was recorded in the tiny Otago town of Milton at 154 micrograms per cubic metre - three times the standard.
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| Evening woodsmoke in a central Otago town |
As reported in our previous post, our current study town of Rangiora has experienced two exceedences of the standard so far this winter.
So what's going on? Each town, and its responsible Regional Council, has had nearly 13 years to meet these targets, including one deadline extension. And why, particularly, Otago?
Overwhelmingly, those towns with the most stubborn air quality problem are also those where air pollution is dominated by woodsmoke from home heating. They are also towns with cold winters and good access to wood. They also tend to be towns with a low population turnover and therefore relatively lower rates of property sales. The inland Otago towns also tend to have more low winds than many other locations because of their valley geography and absence of sea breezes.
Some of this year's offending towns, although they are in breech of the standard this year, are at least still on a downward trend and may comply with the standard at some point in the future. But others are making little progress or are nowhere near compliance. These towns really need a serious re-think, a "Plan B".
But, when seen through from the point of view of the CONA project we also find ourselves asking: How much is the state of compliance or breech dependent upon where the monitoring site has been placed? We've recently shown how Rangiora's monitoring site appears to be in more-or-less the most polluted part of town - as required by the regulations. That was a combination of good judgement and luck on the part of Environment Canterbury. But, if chance had led ECan to select a site a few hundred metres away, the air quality record have been quite different, with (perhaps) the town probably declared to have met the standard some time ago. It is quite plausible that in some other towns we will find the opposite situation - where the official council air quality monitoring site is actually under-representing concentrations in the town and that air quality elsewhere in the town is actually worse than what the monitoring sits says; that the site says the town complies with the standard when actually it does not.
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| The ODIN network revealed large differences in long-term average air quality across the town of Rangiora |
Time will tell....
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