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).
Continuous PM monitoring began in Picton in late 2024 at a new site in Memorial Park near the St John Station where two 5014i BAMs measure PM10 and PM2.5. Unfortunately, serious issues with the PM2.5 machine rendered the first year’s data unreliable and unusable.
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 two monitoring sites
in Redwoodtown, Blenheim and Memorial Park, Picton.
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 g 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.
The highest concentration
recorded in Blenheim was 85 µg/m3 in 2004, but typically the highest
concentrations are between 51-67 µg/m3. In 2024 and 2025 the highest
concentrations were lower, reaching 37 µg/m3 and 44 µg/m3
respectively, these are the lowest since monitoring began.
