Blenheim clocked up a record number of dangerous pollution days this winter.
Data from Blenheim's airshed shows it breached allowed levels 16 times during winter. Photo: LDR / Chloe Ranford
Under New Zealand's air quality laws, councils have to keep track of the coarser PM10 particulate matter and flag when it goes above safe levels.
Data from Blenheim's airshed shows it breached those levels 16 times during winter - a new high. This was despite a new rule being brought in earlier this year which banned braziers over winter, in a bid to lift compliance.
However, there were no breaches during the three weeks at alert levels three and four.
Marlborough District Council environmental scientist Sarah Brand said while the record high was unfortunate, Blenheim was not alone. Several towns around the country had also recorded a higher than normal number of breaches.
The Land Air Water Aotearoa (LAWA) website showed Gisborne has had 27 breaches so far (up 12 from last year), Napier had six breaches (up four), and Taupō had 17 (up from zero).
Marlborough District Council environmental scientist Sarah Brand says the record high is unfortunate. Photo: LDR / Chloe Ranford
Brand thought that Blenheim's breaches might be a reflection of this winter's meteorological conditions, but said she would know more once she analysed the data.
The Marlborough District Council began keeping a log of air pollution in Blenheim in 2006 and since then has struggled to keep to the lawful standard of one breach a year. Previously, the worst year for air pollution was 2017, with 11 breaches.
Air pollutants can come from human activities, like heating or vehicles, or from natural sources, like dust, pollen and salt.
A 2017 report found most of Blenheim's air pollution comes from heating. Photo: LDR / Supplied
Eleven of this year's limit breaches occurred in June (most were one after the other), four in July, and one at the start of August. The highest pollution level was recorded on 4 June.
Brand said warming temperatures and the occasional gust of wind had likely helped Blenheim keep within safe levels over lockdown. Residents were less likely to light a fire or keep it alive for long periods of time during warmer nights.
Air pollution levels also improved under last year's lockdown. Meanwhile, the number of complaints skyrocketed, which the council had since chalked up to more people being at home and noticing what was being burnt in their neighbourhood.
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