Air Quality Instrumentation

​​​The cooler climate and lower population of Tasmania means that the cities are virtually free of the petrochemical smog experienced in the mainland cities and gaseous pollutants like ozone, sulfur dioxide and oxides of nitrogen are close to background levels. 

Instead the major source of air pollution in Tasmania’s cities is fine airborne particles (particularly winter wood smoke from domestic wood heaters).

The concentration of airborne particles is measured using a Tapered Element Oscillating Microbalance (TEOM) or Low Volume Sampler.

Tapered Element Oscillating Microbalance

The Tapered Element Oscillating Microbalance (TEOM) is a low volume air sampler with its filter mounted on the end of a tapered quartz tube, which acts like a tuning fork whose resonant frequency is very sensitive to small changes in the mass of the filter. By making the quartz tube the frequency control element in an electronic oscillator, it is possible to continuously monitor the filter mass via the oscillation frequency. 

A TEOM permits the measurements of airborne particles time scales as short as ten minutes, providing information about the variation of particle concentrations during the day and their correlation with potential sources.

To maintain the frequency stability of the instrument and prevent condensation of moisture on the filter, the TEOM element must be operated at a constant temperature above the highest ambient air temperature (in Australia, this has been set at 50°C). 

PM10 particles can be measured in this way.

​Low Volume Sequential Sampler

Air is drawn through a pre-weighed filter at a known rate, which collects any particles on the surface. The filter is weighed again to determine the mass of particles collected, and by dividing the mass by the total volume of air, we can calculate the concentration of the particles.

Only very small masses of particles are collected on the smaller filters, so a very sensitive balance is used, that can weigh things as small as 0.1 micrograms (one ten-millionth of a gram). The balance and the filters are kept in a room where both the temperature and the amount of moisture in the air is tightly controlled.

In Tasmania, both PM2.5 and PM10 particles are measured in this way.