From our Chair: Winter air
Spring is here, bringing with it daylight saving, lambs, spectacular blossom, and the all-familiar nor’westers blasting away thoughts of cold, smoggy winter nights and replacing them with worries about hay fever.
Our experts have just finished analysing this winter’s air quality, as measured in key locations across the region. The results are encouraging.
Air quality measured against national standards
Air quality monitoring sites around Canterbury measure the concentrations of particles that can be inhaled (PM10 - or particulate matter measuring 10 microns or less in diameter).
The smallest particles can cause significant health effects, particularly for those with asthma and other respiratory diseases. Most of these particles in Canterbury come from the combustion of wood from home heating.
There are government-set standards that each region needs to meet (known as the National Environmental Standards for Air Quality or NESAQ).
In Canterbury, we have the Air Regional Plan that sets out how we intend to reach these standards in our region.
We are not yet at the NESAQ in all the places we monitor the ambient air quality, but the good news out of this winter is that we met the standard in Ashburton, Geraldine, Kaiapoi and Waimate thanks to the action being taken by those communities to address how they are burning wood for winter heating.
Results for winter 2020
Ashburton recorded no days when PM10 concentrations were above 50 micrograms per cubic metre of air, the first time this has occurred. In fact, the highest daily PM10 concentration (49 µg/m3), on 10 July, was the lowest in any year of monitoring, and the winter average PM10 concentration (20 µg/m3) was the second lowest on record.
In Geraldine, the standard for PM10 has now been met for the last five years, which means it can be classified as an unpolluted airshed for PM10. Waimate also did not record a single day with PM10 concentrations above 50 micrograms per cubic metre.
There’s also some good news in Christchurch, from the St Albans site, where there were just two days this winter when the air quality exceeded the compliance limit, the lowest number in 20 years of monitoring.
Unfortunately at Woolston, there were seven, the most at this site since 2014.
The total exceedances for the entire Christchurch airshed in 2020 was eight, which is well above the current NESAQ target of only three high PM10 days a year. This is a reminder there is still much to be done to get the city closer to the target of being an unpolluted airshed.
Kaiapoi had three days of high PM10 concentrations, which met its current target, while Rangiora had four, which is more than last year and above the NESAQ target (of one exceedance only).
Timaru’s 10 days was well above its target of three exceedances of the standards. And Washdyke’s new monitoring site recorded 18 days with PM10 concentration greater than 50 micrograms per cubic metre of air, although the particles measured were mostly coarse and associated with various wind directions, suggesting dust and sea spray sources.
Canterbury's air quality on a positive trend
Generally, air quality is improving across the region. This year’s figures reflect a pleasing trend which started in earnest about 13 or 14 years ago. You can find out a lot more about Canterbury's air quality.
We still have work to do, but we’ve come a long way as a community over a relatively short time.
We now have a whole generation who never had to experience the bad old days of the 1970s and ‘80s, when thick, choking smog would settle in most winter nights over Christchurch and Timaru, and also cloak many of Canterbury’s other urban centres. I can clearly recall biking down Bealey Avenue and nearly choking in the early ‘70s.
This is a great example of a council providing the rules and tools, and the community working to help the community to have better air quality and therefore better health outcomes.