The TEOM consists of a sensor unit which contains the sample inlet (PM10) and the TEOM microbalance for mass measurement. The TEOM microbalance consists of a filter which is held on the end of a tapered tube that oscillates upon particle impaction. As particles land on the filter, the filter mass change is detected as a frequency change in the oscillation of the tapered tube. The control unit of the TEOM houses the processing hardware and flow components. Combining the mass change with the flow rate through the system gives a measure of particulate concentration. The TEOM computes total mass accumulation on the filter as well as 30-minute, 1-hour and 8-hour mass concentration averages. It is therefore capable of providing continuous, real-time data (Australian Standard 3580.9.8).
History of particle monitoring methods
PM10 particles were measured using two different methods; one using a high-volume sampler and the other, a tapered element oscillating microbalance (TEOM) measuring particles continuously. PM10 measurements using high volume samplers was stopped in 2004.
In 1998, ambient air quality standards and goals for six common pollutants (carbon monoxide, lead, nitrogen dioxide, ozone, PM10 particles and sulfur dioxide) were included in the NEPM for all states. NSW Office of Environment and Heritage (OEH) also measures and reports on visibility. In 2006, OEH stopped monitoring lead as levels became undetectable.