Environment Canterbury measures 10PM with FDMS in seven airsheds.
Where does Environment Canterbury monitor air pollution?
Environment Canterbury has permanent air pollution monitoring stations in seven Canterbury towns:
- Kaiapoi
- Rangiora
- Christchurch (St Albans, Riccarton and Woolston)
- Ashburton
- Timaru (Anzac square and Washdyke)
- Waimate
- Geraldine
In the past monitoring has shown that air pollution, maily PM10 , is a problem in these areas and the National Environmental Standards (NES) require us to monitor there. The NES requires Environment Canterbury to measure air pollution in the worst affected area to ensure the whole airshed meets the required standard.
What we monitor
The main contaminant that seems to be a problem in Canterbury towns is suspended particulate PM10. All monitoring stations, except Riccarton, monitor this contaminant. Carbon monoxide (CO) is also monitored at all permanent stations, sulphur dioxide (SO2) is monitored in Christchurch and Timaru and nitrogen dioxide (NO2) is only monitored in Christchurch (Riccarton and St Albans). Summaries of the concentrations measured can be found in the Annual Air Quality Monitoring reports.
Air monitoring reports
How the permanent monitoring stations work
We use a TEOM (Tapered Element Oscillating Microbalance) with a FDMS (Filter Dynamic Measurement System) to find out how much PM10 is in the air.
A small pump sucks air through a filter at a constant rate. The weight of the filter changes with more or less PM10 in the air, and this in turn changes the frequency of a small vibrating element in the machine. The amount of PM10 is calculated from the changed vibration, and the concentration is then sent to Environment Canterbury via the phone lines.
The hourly PM10 concentrations are averaged into a daily concentration (from midnight to midnight),which are compared to the National Environmental Standard of 50 micrograms of PM10 per cubic metre of air.The concentrations are displayed as hourly and daily averages for the past week, month and year at each of the nine sites. The National Environmental Standard requires Christchurch, Timaru, Ashburton, Waimate and Kaiapoi airsheds to have no more than three days a year with PM10 over 50 after 2016 and no more than on day after 2020. Rangiora and Geraldine airsheds must meet the target of no more than one day a year over 50 by 2016.