The main air pollutant in Canterbury is particulate matter smaller than 10 micrometres (PM10). Environment Canterbury monitors PM10 concentrations daily (in real time) across eight geographical areas in the region (known as airsheds) and reports on high pollution nights, or exceedances . This allows Environment Canterbury to compare concentrations with national standards, assess variations over time and understand impacts of local weather conditions . Particulate matter is emitted from the combustion of fuels, such as wood and coal (from home heating and industry) and petrol and diesel from vehicles. PM10 is associated with serious health outcomes such as cancer, respiratory problems, and cardiovascular disease . The Government's National Environmental Standards for Air Quality set different targets for different airsheds (based on the World Health Organization’s guideline) . To meet the standard, the Christchurch City and Kaiapoi airsheds must experience no more than three exceedances per year (no more than one per year from 1 September 2020). Exceedances are when the daily average of PM10 is over 50 micrograms per cubic metre of air. The Rangiora airshed must experience no more than one exceedance per year.
This indicator presents the number of PM10 exceedances per year for Christchurch City, Kaiapoi, and Rangiora.
The figure shows substantial improvements in air quality for all three airsheds since 2008, although some variability is apparent in recent years. For the current (2018) reporting year all three airsheds had fewer PM10 exceedances than in the previous ten years. Christchurch City recorded four exceedances (down from 5 in 2017), Kaiapoi recorded two exceedances (down from 10 in 2017), and Rangiora recorded no exceedances (down from 6 in 2017). Due to the low numbers in 2018, both Kaiapoi and Rangiora airsheds have met the National Environmental Standards for Air Quality, although further reductions are needed in Christchurch City to meet these standards.
Source: Environment Canterbury.
Survey/data set: Air quality monitoring data. Access publicly available data at the Environment Canterbury website www.ecan.govt.nz/your-region/your-environment/air-quality/
Source data frequency: Data collected daily and reported annually in December.