Environment Protection Authority Victoria (EPA) classifies its air monitoring equipment as follows.
General condition monitors: these provide us with information on general air quality and pollution happening over a large area – they give us the ‘big picture’ about air quality. They are strategically placed around the state and they form the foundation of EPA’s monitoring network. Some are fixed and some are mobile.
Local condition monitors: these tell us about local air quality and pollution issues. They are placed in communities where there is a specific pollution concern.
Incident air monitors: these monitors are set up to respond rapidly to a major and specific pollution event. They give us immediate data about the impacts of a pollution event and are used to make decisions about what EPA and other agencies do next. Data collected by some incident air monitors is also shown on EPA AirWatch.
Air monitoring equipment that produces data for EPA’s website
For monitoring small particles – PM10
TEOM – a tapered element oscillating microbalance monitor continually measures the concentration of airborne particles. It does this by collecting and weighing the particles using a very sensitive balance. TEOMs are standard across EPA’s network and meet the Australian National Standard (AS 3580.9.8–2008).
For monitoring small particles – PM2.5
BAM – a standard beta attenuation monitor automatically measures and records airborne particles. This monitor works by collecting particles on a filter tape and measuring the reduction in beta rays travelling through the particles. From this, the concentration of airborne particles is calculated. BAMs meet the Australian National Standard (AS 3580.9.12–2013).
24-hour rolling average data collected by BAMs is used to automatically trigger cautionary health advice on EPA AirWatch.
BAMs are currently used to measure PM2.5 at the following stations: Alphington; Footscray; Geelong South; Morwell South; Morwell East; Traralgon; Moe; and Churchill.
Portable air monitors – these use sensitive, light-scattering sensors to detect particles. These monitors produce indicative PM2.5 data that is usually less accurate than data collected by other types of particle monitors. The portable air monitors provide the community with a more flexible air monitoring network, which allows EPA to monitor air quality at more locations.
Portable air monitors are currently used to measure PM2.5 at the following sites: Box Hill; Brighton; Dandenong; Altona North; Melton; Macleod; and Wangaratta.
Nephelometer – these monitors measure the amount of particles in the air using very sensitive, light-scattering sensors (in a similar way to portable air monitors). Indicative PM2.5 data is calculated from the nephelometer’s visibility reduction reading, which is of a comparable accuracy to the data produced by portable air monitors.
Nephelometers are currently used to measure indicative PM2.5 at the following sites: Mooroolbark and Point Cook.
For measuring visibility
Nephelometer – this monitor measures the amount of particles in the air using very sensitive, light-scattering sensors (in a similar way to the portable air monitors), and calculates a visibility reduction index.
For monitoring gases
Gas analysers – these monitors are used to measure the concentrations of different gases in the air, such as carbon monoxide, nitrogen dioxide, ozone and sulfur dioxide. Each gas is measured by a different analyser.
Monitoring small particles – PM2.5
EPA has a number of different air monitoring monitors that can be used to measure PM2.5
levels. Some of these, such as the BAM and indicative monitors (nephelometers and portable air monitors), produce data that goes on our website. Other monitors (such as Partisols and HiVols) are used as a reference method to ensure the accuracy of EPA’s data. Some types of portable monitors are used to respond to major pollution events.
The diagram below shows their accuracy in relation to each other.