Air Quality Monitoring

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Air Quality Monitoring

Early morning pollution over Blenheim.

Monitoring in Marlborough

Currently Particulate Matter (PM) is the only criteria air contaminant of concern in Marlborough. Monitoring of PM10 (particles less than 10 microns in diameter) initially began in Blenheim 2000 and later short term monitoring occurred in both Picton and Renwick. Since 2006 PM10 has been continuously monitored every hour in Redwoodtown (Blenheim) and a 24-hour average is calculated from the data to be assessed against the National Environmental Standard (NES) for PM10.

Initially measurements were taken using a MetOne Beta Attenuation Monitor (BAM), which was replaced in 2012 with a 5014i BAM. This was joined in 2017 by another 5014i BAM which measures PM2.5, particles less than 2.5 microns in diameter. Between 2000 and 2018 PM10 was also measured using a Hi-Vol monitor which monitored one out of every three days at a site in Springlands (Blenheim).

Why do we monitor Air Quality?

We are required to monitor the air quality where investigations have found that levels are likely to exceed the NES. Marlborough generally has good air quality but during the winter months our air quality reduces due to a combination of meteorological conditions and increased emissions from domestic home heating. PM10 and PM2.5 concentrations peak during winter evenings, when temperatures are coldest and there is little wind and air pollutants can be trapped under an inversion layer.

View more information on inversion layers on our web page

The Marlborough District Council monitors PM10 concentrations relative to the NES at an air monitoring site in Redwoodtown.

Live information can be found on the Land Air Water Aotearoa (LAWA) website:
Go to Land Air Water Aotearoa's website (LAWA)

The National Environmental Standard (NES) for Air Quality

The NES for PM10 allows the threshold of 50 µg m-3 to be exceeded on no more than one day per 12 month period. If this is exceeded the NES has been breached and Council is required to notify exceedances.

Blenheim typically exceeds the NES for PM10 3-5 times a year, but in 2017 it exceeded the NES 10 times, while in 2019 there were no exceedances. The highest concentration recorded was 85 µg m-3 in 2004, but typically the highest concentrations are between 51-67 µg m-3.

Number of days when 50 µg m-3 was exceeded in the Blenheim airshed, the maximum concentration and the second highest concentration from 2006 to 2020

On high pollution days in winter, where exceedances of the NES are observed, there is typically a morning and evening peak in PM10 concentrations.

Further information

Go to MDC's Air Quality Monitoring reports

View Air Quality NES Exceedances