The Otago Regional Council undertook a spatial air quality study on Palmerston and Milton (both airshed 2 towns) last winter to see what the patterns of PM10 were.
Results were used to see if Palmerston needed a continuous air quality monitor and if Milton's monitor was in the place with the worst air quality, a requirement of the National Environmental Standard (NES).
The data taken from 27 sites in Palmerston showed a low-lying corridor that ran from the south of town through to the northeast corner where particulates accumulated.
Council air quality scientist Deborah Mills said PM10 readings taken during the last sampling run in Palmerston were some of the highest real-time figures during any of the mobile monitoring done in Otago.
Earlier monitoring of Palmerston's air quality in 2003 showed it did experience high PM10 levels on occasion, with four of the 14 samples higher than the 50 micrograms per cubic metre NES level.
The topography of Palmerston, hilly with a low, flat area running through town, appeared to have a significant effect on the accumulation and movement of particles, she said.
"Of the entire monitoring campaign, the highest numbers were recorded on this morning run as a thick persistent plume moved slowly through the low-lying corridor."
Continuous monitoring was needed to discover how long the high levels continued.
The results from the Milton study showed the monitor was in the area with the worst air quality with the PM10 values consistently the highest in the southeastern part of the town around the monitor.
The environmental information and science committee recommended monitoring in Milton stay at its present location and that a continous monitor be installed in Palmerston for next winter.
