Timaru’s air pollution levels exceeded environmental standards for an eleventh day this year on Tuesday as Geraldine recorded its first breach of the year.
Environment Canterbury’s monitoring station at Anzac Square, Timaru, recorded a 24 hour average PM10 concentration of 56 micrograms on June 21. The same reading was recorded in Geraldine.
A reading over 50 micrograms of suspended particulate per cubic metre of air indicates “high” pollution under the national environmental standard.
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.
All but two of the breaches in Timaru so-far this year happened in June. The highest reading of the year was 74 micrograms, which was recorded on June 17.
Timaru had ten high pollution days by June 21 last year. Since 1999, there have been anywhere between seven and 23 days of high pollution by the same day.
Environment Canterbury’s Geraldine station recorded two high pollution days by the same time last year. In previous years, anywhere between zero and 5 days of high pollution were recorded there.
So far this year, the Timaru station has recorded the most high pollution days of all centres monitored by the regional council.
Rangiora has had four high pollution days, while Christchurch has had three and Ashburton has had two. In common with Geraldine, the Washdyke station has recorded one breach this year.
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 1.
It drops to one from September 2020.
Timaru’s PM10 readings this year:
June 21: 56 micrograms of suspended particulate per cubic metre of air. The temperature high for the day was 5 degrees celsius; the low was 5 degrees.
June 18: 58 micrograms (11 degrees, 0 degrees)
June 17: 74 micrograms (17 degrees, -3 degrees)
June 16: 55 micrograms (14 degrees, -2 degrees)
June 9: 70 micrograms (16 degrees, -2 degrees)
June 8: 70 micrograms (10 degrees, -5 degrees)
June 7: 73 micrograms (11 degrees, -3 degrees)
June 6: 59 micrograms (13 degrees, -2 degrees)
June 4: 51 micrograms (15 degrees, -2 degrees)
May 2: 51 micrograms
March 10: 55 micrograms
(Source: Environment Canterbury, Metservice)