Arrowtown air quality

Arrowtown had just two high-pollution days this week, bringing this year's total number of high-pollution days to 38.

After milder overnight weekend temperatures, Monday night's minimum temperature fell to -5degC.

Wednesday's value of 20ug/m3 is the lowest since late June.

The most common pollutant is PM10 - particulate matter with a diameter of less than 10 microns.

These very small particles are produced from partially burnt fuel.

In Arrowtown, as in most Central Otago towns, they are emitted from the solid-fuel burners used for domestic heating, as well as outdoor burning.

This weekly graph shows the average daily levels of PM10 recorded at the monitor in Arrowtown during the previous week.