Timaru’s air pollution levels exceeded environmental standards for an eighth day, a week after the last breach.
Environment Canterbury’s monitoring station on Anzac Square recorded a 24 hour average PM10 concentration of 55 micrograms on Thursday.
A reading over 50 micrograms of suspended particulate per cubic metre of air indicates “high” pollution under the national environmental standard.
Readings breached 50 micrograms four times last week. They breached 70 micrograms three of those times.
Timaru had nine high pollution days by the same time last year. Since 1999, there have been anywhere between six and 20 days of high pollution by June 16.
So far this year, the Timaru station has recorded the most high pollution days of all centres monitored by the regional council.
Ashburton, Christchurch and Rangiora have had two high pollution days, while Washdyke has had one.
PM10 refers to particulate matter in the air that is smaller than 10 micrometres in diameter.
PM10 particles are so small that they can get into the lungs, potentially causing serious health problems.
Three main sources of PM10 are home heating, industry and vehicles, from the combustion of fuels such as wood, coal, petrol and diesel.
On a typical winter day in Timaru, an estimated 88 per cent of emissions come from home heating, Environment Canterbury confirmed.
Timaru has an air standard compliance target of three high pollution days from September next year.
It drops to one from September 2020.